My Wife's Polo Green 1993 Allante'

[EmTee]

I'm starting this thread in the vein of the "Me and My Buick" area over on the Buick side.  The subject car is the result of what started out as the quest for a Reatta for my wife.  I touched on some of the cars that we looked at over in the Reatta forum.

 

https://forums.aaca.org/topic/390080-cheap-allante/

 

The quest began with a Reatta convertible that my wife saw recently at a cruise-in while we were in Florida.  She's not usually paying much attention as we wander among the cars, but the lone Reatta present that Sunday morning got her attention.  On the ride home from the event she peppered me with questions about 'those cars' (i.e., Reattas).  With that, the hunt began for a Reatta convertible.  When no convertibles turned-up within a reasonable driving distance, we widened the search to include coupes as well.  Long story short is she spied a couple of Allantes in the area, so we looked at one only a couple of miles from where we were staying.  Though that particular car was a 'pass', she did sit in it and felt comfortable.  The Reatta, even with a 16-way seat just didn't fit as well.  At that point we started focusing on an Allante', which brings me to the subject of this blog...

 

 

 

 

 

As noted above, it's a '93 with 43 Kmi and came with the matching hardtop.  The paperwork I received with the car coupled with what the seller told me indicates that the car was bought new, or nearly so, by someone in the greater Chicago area.  The car was taken to Florida and used there by the owner during the winter months.  Looking at the car, I don't believe it was ever driven in snow.  The seller bought the car from the owner's widow about nine months ago to help settle the estate.  He told me the car had sat unused for 1 ~ 2 years before he bought it.  Good news is he has been driving the car locally a few days every week, so it has been getting regular exercise recently.  The car seems to run smooth and strong, despite the SES being illuminated.  It is also displaying a service message for the RSS on the DIC.  None of these faults seem to affect operation, although I did notice one occasion where leaving a parking space the transmission seemed to be stuck in first gear.  I then noticed the speedometer (analog pointer) was at 0 mph.  It then jumped to 10~15 mph (actual speed) at which point the transmission immediately upshifted.  I'm attributing that episode to the P024 fault.  (So far, that behavior hasn't recurred.)

 

Here's a picture of the service parts code decal:

 

 

As seen above, the last six digits of the VIN are 126709 and it received the 'V4J' engine/transmission updates.  The Northstar idles silky smooth and quiet, while on the outside it appears clean and dry.  That's the good news.  It does, however, have some 'needs'...

 

I dumped the OBD codes and found P024 (VSS) is current.  Also listed in the history were codes P028, P062, T083, R034, S044 and S060.  There were no BCM or Lighting codes.  So, first order of business is to get a copy of the service manual.  I plan to try to keep this thread updated as I work through the process of sorting-out and resolving the gremlins.  I look forward to receiving input from the forum community and hope that this thread will ultimately be helpful to others trying to restore or maintain their Allante'.

[EmTee]

I replaced the VSS on Tuesday.  It wasn't a difficult job, but the bolt that holds the sensor to the transmission case is located behind the sensor connector.  Access is through the RF inner fender, above the axle.  There is a knock sensor right above it, which can remain in-place, however, the plug needs to be removed in order to allow the VSS to be removed from the transmission.  The most difficult part of the job is there's not enough room to get even my 1/4" drive ratchet in there to loosen the retaining bolt.  The bolt can't be seen (because it's on the inboard side of the VSS socket), so it has to be located by feel.  In the end, I had to use the open end of my 10 mm box wrench to loosen the bolt.  The angle of the box-end interfered with other brackets and the transmission case.  So, I resigned myself to moving the wrench about 5° and then flipping it over and doing it again and again and again...  Fortunately it wasn't very tight and once loosened about 1/4 turn I was able to unscrew it with my fingers.  Installation was the reverse of removal.  Test drive seems to show the speedometer needle operates more smoothly (or maybe I'm imagining it).  In any case, the SES is off and P024 is gone.

 

The other thing I did was decided to try to see what I could do about the rust stains in between the spokes of the wheels.  Metallic brake dust was allowed to accumulate and the scallops were stained orange; particularly the front wheels.  I had resolved myself to the fact that I'd probably have to sand and paint the scallops charcoal gray to hide the damage.  I have a tube of Simichrome polish, so I figured there was no harm in trying...  To my surprise, the polish removed all of the iron stains and left only a few very small pits in the chrome on the worst scallops.  The change in appearance was dramatic and the wheels look like new.

 

Before (LF):

 

 

After:

 

[EmTee]

Took the car for a drive to test the VSS yesterday.  Good news is P024 is now gone, but T083 (Low Brake Fluid) showed up, which disabled ABS, TCS and turned on the BRAKE light.  The master cylinder is full, so it looks like a problem with the fluid level switch in the reservoir.  I'll be looking at that today.  Fortunately I now have the factory service manual, which has all of the fault trees and troubleshooting procedures defined.  I plan to flush the brake system with new fluid.

 

 

Edited April 13, 2023 by EmTee (see edit history)

[EmTee]

Sucked old fluid out of the master cylinder and checked for free operation of the fluid level sensor float.  Refilled the master cylinder with fresh fluid and the T083 code is gone.  I still need to flush the brake system because the fluid I removed from the master cylinder reservoir looked amber in color.  Hopefully I'll get to that sometime this weekend.

 

I also troubleshot the cruise control and active suspension fault codes.  I ran the PCM test to cycle the cruise control servo solenoids as directed in the flow diagram in the shop manual.  Looks like the problem is within the servo, which is non-responsive when toggled by the PCM.  Rock Auto has rebuilt ones with exchange, however, I think I'll open mine up first and see whether I can find and fix the issue.  The active suspension test is pointing to an erroneous output from the LF lift/dive position sensor which appears to be reading just outside the allowable range.  I think I'll take that to the bench when I have the wheel off for the brake fluid flush.

 

Lastly, I had a pretty large oil leak which came outta nowhere the other day.  Turned out to be a loose oil filter!  Good thing I didn't drive far and the pan holds 7 quarts...  I tightened the filter and that seems to have resolved the leak.  I am planning to change the oil and filter soon anyway.  More to come...

[EmTee]

Since I replaced the VSS, the car seems to run and drive really well.  Now for the "I told you so" part...  I'm slowly tracing backward schematically in the harness to find the fault with the HVAC blower control.  The 'power module' (fancy transistor version of what used to be 3 wire-wound resistors) was definitely bad (shorted 12V to the load terminal) because the fan would run full speed even with the ignition off.  So, I bought and installed the offshore replacement.  Unfortunately, that had the opposite effect: no blower operation.  Good thing I invested in a gently-used factory shop manual.  I'm currently tracing the fan speed control signal back to the BCM, which generates it.

 

I have been following the fault trees given in my '93 Allante' service manual.  The decision trees are based on setting the control to 'Hi Fan' and then looking for >0.5 Volts at the Gray wire.  The weird thing is I swear I passed that test the first time through and landed at the blower motor as the fault, which I knew couldn't be true.  I then fed the blower 12V directly through a 15A fuse and verified it is good.  The service manual says to check using a 20A fuse to ensure the motor isn't drawing too much current and was responsible for the power module failure.  Since mine ran at less than 15A it is good (as I suspected).

 

I then went back through the fault tree from the beginning and this time failed the >0.5V check at the gray wire.  This sent me down a path tracing that signal first to the 'Programmer' where I found a PC board edge connector with a bunch of green terminals.  I cleaned the board and the connector sockets with contact cleaner and some paper.  The signal wire feeding the Programmer, however, read the same voltage (~0.14V) as the Power Module connector.  So, now I'm in the process of removing the control panel from the center stack to access the connector on the BCM (located behind the control panel) that feeds the Programmer.

 

If it's not already obvious, I would be lost without the factory service manual...

[EmTee]

Here are some pictures for context.  First shows the power module (what used to be done with 3 resistors) removed.

 

 

The first stop while tracing the blower speed control signal backwards to the source is the programmer, which is in front of the glove box.  The signal was bad here as well.  I noted some green corrosion on the connector and PCB contacts, so I cleaned both with electrical contact cleaner since I had it apart.

 

 

 

The next step backward is the BCM, which is the source of the signal.  I was able to access the BCM connectors after removing the left kick panel, driver's side console panel and finally the driver's side knee bolster.

 

 

 

The uppermost connector on the BCM has the blower control signal.  Backprobing the pin showed the same ~0.14 Volt reading I had seen at the power module.  I unplugged the connector and checked the wire going from the BCM to the programmer in order to rule-out a shorted wire.  That test was good (no short).  Lastly, I checked the voltage directly at the BCM pin and verified the signal is bad.  With that, the BCM is at fault and needs to be replaced.  I ordered a remanufactured BCM from Rock Auto which should arrive mid-week.  I have the center stack unbolted from the dash, ready to slip out once the new BCM arrives.

 

Finally, here's a snapshot from the shop manual showing the blower control schematic.

 

[EmTee]

While waiting for the new BCM to arrive i figured I'd take a look at the bad cruise control servo.  I removed it from the car and brought it to the bench.  I used my mighty-vac to check for vacuum leaks and the vacuum input held vacuum.  Next, I disassembled it to reveal the vacuum switch solenoid coils and the vacuum valve bodies.  Mechanically everything looked OK, so I just cleaned the parts and reassembled the valves.  Last step was to check the solenoid valves electrically.  I was able to read continuity through 2 of the 3 solenoid coils; the 3rd one read 'open'.  Upon closer inspection I found a few loose coils of wire near one end of the solenoid body,  By carefully picking at the wire I was able to find the break in the wire and bring the two ends out where I could work with them.  I trimmed the wires back a bit and used a utility knife to strip the lacquer off the ends before twisting them together.  I checked continuity with my meter and the coil now read like the others.  I soldered the joint and insulated the end with some heat-shrink tubing.  Lastly, I glued the splice to the coil with a dollop of epoxy to secure the repair from vibration.  All assembled, the servo checks OK with my meter, so I'm hopeful that it will actually work once I get the BCM repair finished and can take the car out for a test drive.  The first real test will be to see whether the fault code reappears when I switch the cruise 'on'.

[padgett]

Currently I have three cars that use that same HVAC control module (cars with ATC got the module, manual temp control the resistors) and always salvage/checkout a spare or two. Relays, oil pressure senders, and HVAC modules are the most common failure in period halo cars.

Since you have a 93 with no engine leaks, you are lucky, very lucky.

[EmTee]

The remanufactured BCM arrived yesterday.  It is a Blue Streak unit that appears as new.  Instructions were to transfer the PROM, CAL and a 3rd chip (?) from the old BCM to the new one and transfer the cover from the old to new.  The chip swap went without issue, the ICs are installed in carriers which protect the pins and make it impossible to install them in the wrong orientation.

 

I had the center stack loose and ready to remove already, so that went quickly.  Fortunately the connecting cable is long enough to allow setting the center stack aside without having to disconnect it.

 

 

Before the BCM can be removed, however, the ABS/TCM (see above) has to come out.  Removing one bolt allows it to be freed from its bracket and maneuvered out of the dash enclosure.  Like the center stack, this also has sufficient cable to allow it to be removed and set aside without disconnection.

 

With everything else out of the way the BCM can be unplugged and removed after removing one bolt at the top.  Two pins on the unit fit into a support at the bottom.  The BCM bracket needs to be unbolted and transferred to the new BCM along with the two bottom mounting pins.

 

 

I installed the new BCM and replaced the ABS/TCM and the center stack.  I re-connected the connector that I had cleaned at the Programmer and re-connected the battery.  Turning the ignition ON started the system checks and the DIC showed "MONITORED SYSTEMS OK" - a good sign.  (With the Programmer disconnected it would say "SYSTEM FAULT").

 

So, I set the HVAC controls for HI FAN and...  NOTHING!    I went back to the book and followed the HVAC blower fault tree once again...  This time, however, when I came to the step to check the fan control signal at the Power Module connector (GRY/BLK) I saw ~12 Volts!  This was with the engine running and the power supply input voltage of about 14 Volts on the 2-pin connector.  I re-verified the blower motor using the 15 Amp fuse and it is still good.  I also verified that the blower output/programmer feedback wire to the Programmer was not shorted to ground.

 

Long story short, the book led me to the Power Module as the fault.  Note that the output transistor on the original is shorted so the fan was always ON.  The replacement I bought was an offshore piece that fit, but apparently doesn't function as original.  Now, even with ~12 Volts on the control input it only output about 2 Volts.  With that I went back and ordered what appears to be the last AC Delco Power Module that Rock Auto has in stock.  I started the Ebay return process on the offshore module.  I should know better, but at ~1/2 the price of the AC Delco part, I figured the Brand X piece was worth a try.  Fortunately it only takes about 5 minutes to install the power Module.  The worst part is having to wait once more before buttoning everything up...

 

Edited May 5, 2023 by EmTee
typo (see edit history)

[padgett]

I used to scrounge yards for electronic parts and had about a 85% success rate. Now I do not buy AC parts (made in China) but for new mostly Bosch or Standard (SPC).

[EmTee]

I put the car together just enough so I could drive it (had to get the lawn tractor out of the garage).  I took it for a ride just to keep the blood flowing.  On the way back to the house I accelerated to 60 mph and hit the Cruise button - Voila!  "CRUISE" appeared on the speedometer dial and I took my foot off the accelerator.  My vacuum solenoid repair seems to be working. 

[EmTee]

Another good day today.  The AC/Delco blower module arrived from Rock Auto.

 

 

This one looks very similar to the 'Brand X' one that I bought on Ebay, except this one WORKS!  The blower now operates as intended.  Speed varies as I adjust the auto climate temperature setting.  Both the Lo and Hi fan settings also function.  So, in summary, there were two issues with the blower: (1) the power module was bad (shorted) and (2) the BCM blower control circuitry was also faulty.  I suppose it could be that the power module may have fried the BCM, or maybe it was just coincidence.

 

With the blower working, I can now reassemble the driver's knee bolster and button-up the interior panels that I removed to support the troubleshooting and BCM replacement.  The next item to address is the low refrigerant in the A/C system.  I bought two 12 oz. cans of R134A (it has been retrofitted) and will connect my gauges and see what is up later in the week when temps are supposed to be near 80° F.

 

Feels good to finally have the blower problem licked! 

[EmTee]

The "Low Brake Fluid" alert (Code 83) has been coming up intermittently since the day I first test-drove the car.  It is a false fault, as the brake fluid level is not actually low and the pedal feels fine.  At first I thought the magnetic float in the reservoir was sticking, so I sucked-out the fluid and checked with my finger to see whether the float moved freely.  It seemed to be free, so I refilled the reservoir with fresh fluid.  It was fine for a couple of days, but then the code came back.  I next wanted to rule-out a sunk float, so I removed the reed switch from the reservoir and just set it aside so that there would be no way for the float to activate it.  Once again, it was OK for a day or two and then the fault returned.  This particular fault resets itself at each ignition cycle, so no manual reset is needed.  After a couple of weeks running with the switch removed from the reservoir, I began to notice a pattern.  The switch seems to fail when the after the car is driven awhile (i.e., hot under the hood).  This particular switch seems to be unique to cars with ABS and traction control.  I bought a switch online for a '93 Eldorado.  When I got the switch I discovered that it did not include the 2.2K Ohm resistor as shown in the shop manual schematic (see below circled in red).

 

 

The problem, however, is the original-style switch seems to be discontinued and I could not find any on Ebay or other online sources.  As a workaround solution I decided to add a 2.2K Ohm resistor between the two switch wires (circuits 853 and 736) to emulate the resistor built into the original-style switch.  That allowed me to use the commonly available (non-traction control) version of the switch.  The switch is normally open, so the external 2.2K Ohm resistor satisfies the BCM test circuitry.  If the fluid level does become low, the magnetic float should close the reed switch, shorting-out the resistor and causing the BCM to set Code 83.  Here's a picture of the switch harness modified to include the parallel 2.2K Ohm resistor.

 

 

So far, so good - but I'll need to drive the car for a week or two without seeing the low brake fluid fault before I can say for certain this problem is fixed... 

[EmTee]

So far, so good with the Low Brake Fluid Level fix.  No false alarms yet.

 

Yesterday I decided it was time to flush the brake system.  The fluid I sucked out of the reservoir when checking the level float looked bad (dark in color).  So, I used my bleeder cup to flush fresh fluid throughout the system following the order specified in the service manual: LF, RF, LR then RR.  The stuff that came out looked like coffee...  I went through about 1 1/2 quarts of DOT 3 fluid.  I hope this helps prevent further component damage or degradation.  I still need to change the engine oil and coolant.

[EmTee]

The low brake fluid fix is still good - no false alarms and the brakes are working well since I flushed the fluid.  (Actually, they worked OK before but the fluid looked like crap.)

 

The next job I tackled was the non-working A/C.  A 'low refrigerant' message was displayed on the DIC and as a result the compressor would not run.  I hooked-up my gauge set and the low side registered less than 20 psi.  I decided to try adding some R-134a (the system was converted by one of the two previous owners).  Once the low side gauge hit about 20 psi the compressor started short-cycling.  Even with the compressor on I was reading 0 psi on the high side.  At that point, I decided to stop and assess the situation.  I re-read the A/C section of the shop manual which indicates that the high-side service port does not use a typical Schrader valve (as the low-side does).

 

 

There is a special fitting/tool (J-38702) that opens the high side port and includes a Schrader valve.  I found one on Ebay and ordered it.

 

 

Last weekend I decided to try again using the high-side adapter.  First, I had to remove the R-134a adapter from the high-side port (which was useless anyway).  Then I installed the J-38702 adapter and the high-side gauge.  The low-side worked fine, so I left the R-134a adapter in place there.  With the gauges connected I started the car and turned on the A/C.  As before, it was short-cycling and the car actually stalled once.  Before the next attempt, I attached a can of R-134a to be ready.  I started the car and as soon as the compressor came on I opened the low side valve and started adding refrigerant.  I checked that both radiator fans were running at high speed and low side pressure slowly increased.  Once low side pressure reached about 30 psi, the cycling period increased and became more 'normal'.  Since the system was designed for R-12, there is no prescribed amount of R-134a.  I decided to follow the "Insufficient Cooling Quick Check" procedure in the shop manual to determine when an appropriate level of R134a is in the system.

 

 

When the temperatures of the evaporator inlet tube and accumulator were equivalent and the evaporator tube was sweating I stopped adding refrigerant.  The thermometer in the center dash vent was reading ~47 degrees F at an ambient air temperature of ~79 degrees F.  With the compressor running, the final low-side pressure was 38 psi and the high-side pressure was 220 psi.  Resting pressure settled to 80 psi on both sides.

 

I'll run it this way for awhile and keep tabs on performance.  I have ordered a halogen leak detector and will check the service ports, pressure switches and other connections for leaks once that arrives.  I'm hopeful that refrigerant was leaking from the low-side Schrader valve, as the shop manual states will happen if it is left uncapped...

 

Edited May 31, 2023 by EmTee (see edit history)

[EmTee]

So, I attempted to raise the soft top on the Allante' the other day since Summer is winding down and the recent forecasts have included the chance of scattered showers.  The task went sideways as soon as I tried to raise the boot/cover...

 

 

Pulling the "Cover Open" lever did nothing.  The cover remained latched.  I tried pressing down while pulling the lever with no joy.  I looked up under the cover latch and found the two bolts attaching the latch to the body.  I removed them, thinking I might be able to raise the cover with the latch attached in order to gain better access to figure out what was jammed.  Well, with the bolts removed, the latch was blocked by a plastic cover that is trapped under the boot.  After tens of minutes of 'fiddling' and looking through the shop manual (which was no help in this case) I accidentally discovered that the latch design is essentially just like the usual GM trunk latch.  It turns out that there's a round shaft with a slotted hole through it just like one that would receive the metal tab attached to a trunk lock cylinder.  I stuck a right-angle screwdriver into the hole and twisted it and the latch popped open!  I marked the latch body with an arrow to show the direction to turn in order to release the latch (counterclockwise).

 

 

Disassembling the latch revealed the root cause of the problem.  The latch release cable is attached to a plastic crank that trips the latch internally.

 

 

The cable stop was a very small bead that pulled-through the plastic lever and split the hole that the cable passes through.  I bought a new cable stop ferrule and release latch cable 'loop ferrule' at Ace Hardware.  I removed the bead and crimped the new, larger cable stop, backed by a small washer, onto the actuator cable.

 

 

The new stop with washer is large enough that it won't pull through the hole in the plastic lever.  I reassembled the latch, lubricated the mechanism and tested it many times before reinstalling it on the car.  The last part of reassembly was to install the new loop ferrule on the cable attached to the "Cover Open" lever.

 

 

Lastly, with the latch assembly loosely attached, I closed the cover and adjusted the latch position to engage the cover bail and hold the cover down at the proper height.

 

 

Now, should this ever happen again, I can look up under the cover latch and see where to insert a tool and which direction to turn in order to actuate the 'emergency' latch release.

 

 

I'm still puzzled why the shop manual does not mention this alternate latch release capability...

[EmTee]

After topping-off the R-134a (system was converted from R-12 by the PO) twice, only to have it gradually leak out through the high-side port after a month or so, I took it to my mechanic to have him remove the refrigerant and replace the valve on the port.  The leak had persisted, despite my attempts to secure it with a cap.  They evacuated the system, replaced the high-side port Schrader valve, checked for leaks, refilled the system and added dye (to support future troubleshooting).  A/C now blowing cold again - hopefully for the last time...

[rodneybeauchamp]

Some great diagnosis happening here, with perseverance too! 
 

Interested in what code reader you are using (gather it is OBD11) as I am considering getting one for the ‘97 Riviera.

 

Must admit you are accumulating lots of Brownie points here, or is it EmTee who really likes the Allante?

Rodney 😀😀😀😀😀😀😀

[EmTee]

15 minutes ago, rodneybeauchamp said:

Interested in what code reader you are using (gather it is OBD11) as I am considering getting one for the ‘97 Riviera.

The Allante' is a 1993 model, so it's OBD-1, not OBD-2.  Most OBD-1 cars require counting SES light flashes after grounding a pin in the data connector to determine the fault code(s).  Fortunately, this car has the diagnostic reader built-in, and uses the display on the Driver Information Center (DIC) on the center stack to display fault codes and data.  Pressing the OFF and the HOT (increasing temperature) buttons simultaneously for 5 seconds puts the system into diagnostic mode.  Faults are displayed and pressing specific dashboard buttons allows selected tests to be performed, data inputs/outputs to be observed, or overrides to be initiated.  It is really comprehensive and quite impressive.  It also makes it clear that I would be lost without the factory service manual!

 

Since your Riviera is post-1996, it has the OBD-2 system and an external diagnostic reader can be used to access fault codes and data.  I have an Actron OBD-2 reader that I have had for at least 15 years.  It works well and so far has been sufficient for me to diagnose issues with my more modern vehicles.  The only thing it doesn't do is read brake/traction control (TCM) or body control module (BCM) faults.  It supports powertrain control module (PCM) diagnosis only.

 

 

My first recommendation for you is to get a copy of the factory shop manual.  The one for the Allante' is the size of the Manhattan phone book and is packed with vital information necessary to diagnose, repair and maintain the car.  I found mine on Ebay, in very good condition, for about $80.00 US.  It has already paid for itself! 

[rodneybeauchamp]

5 minutes ago, EmTee said:

 

 

My first recommendation for you is to get a copy of the factory shop manual.  The one for the Allante' is the size of the Manhattan phone book and is packed with vital information necessary to diagnose, repair and maintain the car.  I found mine on Ebay, in very good condition, for about $80.00 US.  It has already paid for itself! 

EmTee, happening as we speak. Had been searching a while and even put out a post here and finally pulled the trigger on a set last week. It was well tested in a shop with some genuine Buick Riviera grease and stains to boot. The shipping to Australia cost more than the books!

Rodney 😀😀😀😀

[EmTee]

Well, it's been awhile with no issues to report, until now...  The other day my wife came home from an errand and parked the Allante' in front of the garage.  When I started the car to pull it into the garage the "Check Driver Info" telltale was on in the center of the instrument cluster and the DIC displayed the message: "STOP ENGINE OVERHEATED".  Hmmm...  The temp gauge was dead center and there was no evidence of overheating.  There were no PCM or BCM fault codes.  I entered the diagnostic mode and confirmed that the coolant temperature sensor value is good and tracks the reading displayed by the gauge.

 

I reviewed the service manual and the associated schematics and began to suspect a possible short in one of the discrete signal lines from the BCM to the cluster.  I traced the wire and verified the voltage present was IAW the manual (>10 VDC).  The problem is intermittent.  I put everything back together and went for a drive yesterday.  The message was displayed when I pulled out of the driveway and remained on for a couple of miles before it cleared.  I drove for about 10 miles with no message and pulled into the driveway and turned the car off.  I immediately restarted it and the message came back.  The car acts perfectly normal and this is obviously a false alarm.  I am now suspecting an issue with the serial interface from the BCM.  Recall that I replaced the BCM with a Blue Streak remanufactured unit last May to resolve an issue with the HVAC blower control.  I checked Rock Auto and the BCM is still available and the one in the car is still under warranty.  I'm going to study the service manual some more to identify any other possible causes and monitor the situation for now.

 

To be continued...

[60FlatTop]

I have three '05s, a Cadillac STS V8 RWD, my Silverado, and an Avalanche. I bought the full set of manuals for the Silverado when it was new and sold them about 12 or 13 years later without using them much. The manuals for the STS are still $500 on Ebay. ALLDATA.com offers a single car DYI subscription for $19.95 per month. I bought that for the STS just to read through randomly to get familiar with the car. They offered a year at $60 and I upgraded.

 

For 20 bucks that monthly fee is not bad for any job that may be greater than routine, worth it for a single job. If anything big comes up with the Avalanche I will subscribe right away.

 

Just a heads up to let owners know that help is available at low cost for the modern cars.

 

ALLDATA is an Auto Zone product.

[EmTee]

Thanks, Bernie I know you've mentioned ALLDATA before.  The shop manual is a bit cryptic sometimes and information isn't necessarily located where I'd expect to find it.  I may just give ALLDATA a try if I don't get satisfaction from the shop manual.

[Tpcook]

I followed your discussion of the Green Allante. Recently I went thru 4 different blower motor resistors from several sources. None of them worked. I did find a part made by Standard Motor Products which did work RU540.  I bought from rock Auto but others will also have this part. 1989 Allante Red with beige interior.

Edited May 23 by Tpcook (see edit history)

[EmTee]

Update #1:

 

The "Low Refrigerant" issue occurred again over the winter and I topped-off the system again.  This, after fixing the leak at the high-pressure port.  Last week I took the car in and had the shop that fixed the port leak look it over.  They had added dye when they refilled it so we looked over the engine bay with a blacklight and didn't see any leaks.  Next, they raised the car on the lift and we quickly saw dye slobbered along the bottom of the compressor beginning behind the clutch.

 

So, I ordered a new compressor, accumulator and orifice tube for R-134a from Rock Auto.

 

 

Hopefully this will fix the problem once and for all.

 

Update #2:

 

So far, there has been no recurrence of the "STOP ENGINE OVERHEATED" false alarm (knock on wood).

[EmTee]

Finally got around to having the new A/C compressor installed.  One hiccup that we ran into was a slight difference in the hose manifold interface between the original Harrison H6 compressor and the new Four Seasons H10 replacement.  The inlet/outlet sealing surfaces on the original compressor were the on the same plane (i.e., identical depth).  The new compressor, however, has one of the sealing interfaces countersunk approximately 1/8" deeper.  At first we thought the compressor application was incorrect, so I called Four Seasons technical support.  I had some difficulty finding the support phone number on their website, but to their credit, an actual human answered the phone after a few rings and she directed my call to a tech support person.  I explained the situation with the offset interface depth and the representative said "they've been making them that way for 25 years".  I told him that the problem is my car is 30 years old!  He said that I need Four Seasons seal adapter kit #24342, and he was surprised that it wasn't included with the kit.  I gave the information to my mechanic, who made a phone call and found the adapter seal kit locally and had it delivered to his shop.  The kit includes thicker sealing washers designed to make-up the difference in height so the original hose manifold will work.

 

The other notable discovery was a few aluminum flecks stuck to the screen on the old orifice tube.

 

 

So, the compressor was obviously running on borrowed time and the leak was just one issue.  I think the compressor was changed just in time.  (I had one 'grenade' on a different car years ago and it was never the same afterward.)  The system is now fully functional and blows cold air again.

 

FYI, compressor and accumulator P/Ns pictured below.

 

[Lusso]

Just found this 'site. Many thanks for your above-and-beyond efforts to clearly and thoroughly outline various repair procedures on your V4J. I have one too that was stalled (felt overwhelmed), but now I'm picking up the gauntlet again. 

 

Best Regards,
Wil

[EmTee]

Well, good news is the A/C is working well; bad news is the "STOP ENGINE / ENGINE OVERHEATED" message has popped-up on the DIC again.  The couple of times it has happened recently, however, was right after the initial system check on the initial startup after sitting overnight (i.e., the engine is stone cold).  Unlike previous occurrences, the message appeared and then cleared immediately.  I'm still trying to figure out what exactly triggers that message.  I'm suspecting a possible high-resistance path to ground somewhere, but everything I have looked at so far appears to be clean and tight.  The temperature sender appears to be functioning normally and reports what looks like actual coolant temperature.  The analog temperature gauge never goes past the midway point between "C" and "H".  The hunt continues...