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1988 Buick Reatta Electrical Nightmare


Guest jonate88

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Guest jonate88

Just acquired an 88 Buick Reatta.. runs and drives great but the inside is really moldy and it seems a lot of moisture in the car. This car has a high tech Digital Dash and Touch Screen. None of it works, I'm pretty good with wiring but have no idea were to start. Fuses are all good connections seem solid.

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Guest my3buicks

Hi John, you need to move your thread down into the Buick section of the forum and more importantly into the Reatta section of it. There is a ton of knowledgeable folks on there. Water/moisture and complicated electronics don't mix well for sure.

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You are really going to need a factory service manual to effectively troublshoot this. Search ebay for "1988 reatta service manual" and pick one up. Make sure it is one marked "final edition" as in 1988 there was a preliminary service manual that was incomplete. 88 manual has a dark blue cover with a red bar that says "final edition". Not to be confused with the 1990 edition that is also dark blue.

One thing I expect you will need to deal with are the ground splices under the seats in the floor pan wire raceway, if that much moisture has gotten into the car. Outside of that, if you have verified fuses are good, you will need to check for proper voltages at the harness connectors for the IPC and CRT to start determining where the failure lies. From there the problem can branch out in several ways. Hence the need for a manual (generally referred to here as the FSM).

In any case, feel free to post here with your questions, as there are several experienced troubleshooters on here. We will make a solid run at helping out any way we can.

KDirk

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A 1988 service manual just sold on Ebay for $15.50

Start by removing the passanger seat, the door sill, and fold back the carpet. You will find the plastic channels that hold the wires. Note that there is a "T" under the seat and once you get down to the wiring you may find standing water. In the area of the "T" there are 5-6 electrical splices (wrapped with electrical tape) "Each splice has several wires (it varies with each splice) terminated with a steel sleeve crimped on the wires.

The water/moisture has rusted the steel splice over the years and you no longer have continuity between all of the wires.

You need to cut off the splice, strip the wires, clean the copper and recrimp with a copper sleeve........ I then flow solder into the crimped sleeve.

Do this to all the splices and some of your electrical problems will go away.

The next step is to unplug some of the devices that are not working, clean the connector contacts, spray them with contact cleaner/lube and re-connect, this will get more things working.

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Guest jonate88

Thanks everyone for the advice. I have repaired all of the splices under the seats and traced the problem and it seems none of the relays are working. I have power on the hot side of the Relay windings and on the hot side of the switch side. I assume these are ground side switched by the BCM? When i jumped the relay for the fog lights and interior lights for example they work fine. It seems either my BCM is not grounded properly or its not getting a signal to activate these relays. Any advice would be appreciated.

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Guest jonate88

I cleaned them all. Does anyone have the wiring diagram for the BCM? I want to check all of the wires going into and out of the BCM to be 100% sure that's the problem.

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Can download the 89 FSM from reatta.net (must register, was required for permission) and is very similar to 88. If it is running/driving the ECM must be working. Keep im mind that this is a very early computer car so everything has its own module.

Let's start with what does work ?

BTW what you are looking for the the Factory service manual for 1988 Buick Riviera and Reatta "E" (sometimes have better luck looking for "Riviera")

ps Do you have access to an ALDL scan tool like an OTC 2000 ? That can display most of what the digital dash shows.

Edited by padgett (see edit history)
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Hang in there! These guys on this forum and at ROJ are the best! They are very knowledgeable in every aspect of the Reatta. (electrical, mechanical, body) I have been working on cars for most of my 60 years on this earth and I have always found that I could do most anything without a lot of help and using manuals. But I come here to the forum all the time since I got the 88 Reatta coupe because it is much easier to listen to someone who has already "been there - done that". I found these sites when I was looking for parts to fix my headlights and was very happy to stumble upon this crowd.

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Guest jonate88

I'm hanging in there. I was poking at wires with a test light at the BCM, when i hit this Blue wire with the Orange stripe it made my dash come on but still doesn't register the speed it gave me hope. I'm leaning towards the BCM itself because everything that doesn't work runs through that. When I got the car all of the lights around the touch screen would work but now its just the radio.

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Guest Mc_Reatta

That's the IPC wake up line. What happened when you hit the light green wire in the far bottom end on the red connector? (just across from the position you hit, but on the red connector) That's the CRT wake up line.

Think you are correct about the BCM. If you have checked you have voltage coming in and ground, then you will need to swap it. The 88 had its own BCM so you can't swap it with another year, Also the PROM was unique to the 88 as well. Might want to verify the PN of the unit is 1227333 and the prom with the operating software is marked AKTH. But even if someone swapped in an incorrect unit or PROM, it shouldn't result in all of the issues you have.

Do you have a voltmeter and access to the online FSM yet?

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Guest jonate88

I need access to the FSM but I don't yet. Nothing happened when i hit the Green Wire but when i wiggle the connector my speedometer display goes crazy and says Error were the mileage was. The RAP isn't working either because the radio goes dead as soon as i turn the key off, That's also part of the BCM correct? I'm not completely sure I have checked every power and ground going into the BCM because i dont have a schematic of it but i desperately need one. All of the problems seem to be pointing to the BCM but I want to be completely sure.

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Guest Mc_Reatta

Have you checked for corrosion on the pins in the BCM and in the connectors. The appearance of error in the odometer indicates the BCM is at least awake. By wiggling the connectors you are confirming a poor connection either inside the unit, at the connectors, or in the wires near the connector. Since your car was damp for some time, you may really have to get aggressive with cleaning them. might try disconnecting the battery and spraying with CLR or Lime Away to dissolve corrosion you can't get at other ways, then rinse that off with contact cleaner and let dry before reconnecting and testing.

Yes, the RAP relays are controlled by the BCM too.

Main power is supplied on a brown wire with white stripe (from the 3 amp BCC/ACC fuse) that is in the center (#8) position on the top row (side with clip) on the outboard black connector. You can verify that it's getting there.

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Guest Mc_Reatta
My SVC# is 01227333 but the Prom says AMTR. Could that be a problem?

Your PROM is listed along with AKTH under the same PN for an 88. It is probably an alternate (early/late production, export?) and I don't think it would be the problem. There is not as much documentation for the BCM PROMs as the ECM PROMs to confirm what the difference between those two would be.

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Just to chime in, my early 88 has a much longer lights on exit delay than the later production 88 I own. Since the timer for this function is controlled by the BCM I am certain there are at least two different BCM PROM versions. Don't have the ID codes handy but there have to be at least two valid ones for 88.

I also suspect a failed BCM is the cause of the problems the OP is having. Cleaning the connections is easy enough to do first (and should be just to rule them out) but I am expecting a new BCM is in your future.

Partial failures of the BCM and ECM can be terribly frustrating to troubleshoot as they can mimic bad switches, relays, wiring and connectors. Especially with intermittents. If you can get good modules from a salvage car of the same year, by all means do so as they are generally cheap and you will need spares eventually. Also nice to have spares to swap in for troubleshooting cases like the one presently under discussion.

Nonetheless, proper structured troubleshooting is critical to nailing down these sorts of problems. Sounds like you are on the right track but really need the FSM to do a thorough job.

KDirk

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Guest Mc_Reatta

Kevin, it would be good if you could note those codes and update the PROM ID Project thread we started a while back. You might start with the Scan ID #s as you don't have to pull the unit apart to get them. Early / late production differences would certainly make sense why there are two different codes listed as I don't think California car BCM programming would be different, and export differences can be user programmed via the option codes. (Don't think Cali cars came to be until 89 anyway) Surprised GM kept the same PN though instead of issuing new ones. Guess they wanted to obsolete the first ones though not bothering to replace those that had been sold. Think the parts book lists two codes for the 89 BCMs as well. I'm guessing the first one listed is the later one, and the second # is the early one. I'll edit my post in the PROM thread to reflect the optional codes for those years.

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MC-

I have intended to do just that but lack of time - and now the onset of winter weather - have kept me from pulling both BCM's to get the letter codes from both cars. I will endeavor to get the scan ID on both in the next few days. I have the late 88 in offsite storage presently and driving the early 88 at the moment but will switch them out next week. Will add pertinent data to the PROM thread as I get it.

If we have a stretch of decent weather here, I'll try to get the BCM's pulled so I can get the letter codes.

KDirk

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Guest Mc_Reatta

Kevin, Sounds like a plan. Seems like we're reaching the end of the flat run of the failure rate curve of the ECMs and BCMs. Judging by the number of posts with computer problems recently it may be starting to take off.

Need for PROMs will go up as folks swap computers and forget to do the PROMs, then give up and sell the car cheap leaving the new owner in the lurch. They'll be looking at you for help in getting a proper replacement.

Hope you can enjoy the holidays while keeping up with all your projects, and are safely away from all the unrest in Ferguson.

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Yeah, I think the effects of age are exhibiting themselves now WRT the electronics. Pretty remarkable track record that these modules have typically lasted a quarter century before showing signs of distress. That may well exceed mil-spec hardware. For all the criticism I can level at the General - past and present - they did exceedingly well in the design and manufacture of these aluminum clad bricks.

I have no problem being a source for PROMS if it comes to that. I hope we don't start seeing cars junked or parted due to mismatched PROMS from shade-tree repairs. However, I fear we may see that as there seem to be more than a few owners who are uniformed on the particulars of how the PROMS relate to a module/year by application and the problems that relate to mis-matches.

GM didn't help matters by failing to have published a concise cross reference all in one place; which is what I was wanting to do with the PROM thread. We are very nearly there now with the help of multiple contributors.

The next stage is for me to get all the major PROMS by module and year (and sub-variants thereof) dumped to .BIN files and find a place to host those files for posterity (besides my myriad fixed disks spread across 5 different computers). Some progress has been made in dumping chips, my last visit to Dave's Reattatorium yielded some additional PROM images. I have more yet to do: both variants of the CRTC, some ECM and BCM particularly 1990 models since I don't own one. Slowly but surely I am building a code library.

I will refrain from commenting on the present situation in Ferguson except to say I am well away from the epicenter of discontent. Nothing more can be said without tweaking someone's ideology, and this isn't the setting for such discourse.

KDirk

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Guest jonate88

I have voltage at the brown wire with white stripe so I'm going to get a BCM. Does anyone have extra BCM Connectors with wires attached? I would just like to get all new connectors and solder them to my harness, some of these metal connectors don't seem like they will last much longer after being exposed to so much corrosion.

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Ouch. That's a lot of splicing to do. Might be better off finding a junk 88 and get the entire dash harness from it. Especially since the BCM connectors are probably not the only ones affected if there is that much corrosion. The ECM and it's harness is right under it, and of course the CPS, CRTC and radio modules and associated wiring are all closer to the floor pan making them susceptible to as much or more ambient moisture damage as the modules up in the dash.

May I ask how so much moisture go into the car? Bad or missing glass, weather strips, sunroof stuck open? Sounds like a terrible mess. I hope you can bring it back from it's current challenged state, but wonder what other nasty surprises it may hit you with if that much water got into the cockpit. Could be looking at rot in the floor pan, severe mildew/mold in the carpet and ongoing corrosion in wiring, connectors and modules. This is why flood cars are usually a writeoff. I presume yours was not invloved in a flood but rather subject to moisture ingress while stored for some time.

KDirk

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Guest jonate88

I am starting to think it was flooded, i have already pulled the carpet out and repaired those splices. The body and subframe seem solid with little surface rust on the subframe. It runs great, the radio works and can be controlled by pushing on the screen just has no display on the console or the speedometer. A good bit of mold and mildew but nothing a little elbow grease cant fix. I would just feel better if i could get new connectors, i don't really have the money for an entire harness.

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Well, connectors from another car can be spliced on but should be done with proper soldering and heatshrink tubing applied to each lead. Even then, I'd be leary of the long term reliability of having that many splices in such a large harness.

I am surprised that the BCM and it's portion of the harness would be only thing so badly damaged if the car were flooded. Figure the floor pan would fill up first taking out the radio, CRT controller and damaging the splices (the latter evidently did happen). Unless those modules were changed prior to your purchase of the car, I'd think everything embedded in the center console would have been trashed including the harness connectors. Then again, stranger things have happened.

I'd check with Jim Finn for the connectors (and ask him what a complete dash harness would run too) as well as any local salvage yards. Keep in mind that while the 88 Riviera and Toronado are very similar electrically, there are a few differences in the BCM harness used in the Reatta. I'd try to get the connectors (or harness if possible) from an 88 Reatta. 89 is a bit different as well, so try to avoid using connectors and wiring from one if at all possible.

KDirk

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Guest jonate88

It just seems the BCM is very sensitive to any extra resistance because it works with such low voltage that i don't want to take any chances down the road of having intermittent problems from the connectors. I hope i wont be replacing the entire harness.

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If money isn't the issue I would replace the harness. When Kevin came up to get parts from Gibson's as well as the Reatta we were stripping [which we removed the dash and pulled the harness]. Took less then an hour, which would be a lot less time then doing all the soldering that you would be required to do.

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Guest jonate88

Okay, i just got my new BCM. The RAP now works, my dash comes on without my help, and the interior lights work. My touch screen works but i have no illumination I suspect its the module that controls it that's under the dash. Does anyone know a reliable place to get one? Also my speedometer doesn't work. Yesterday it worked for about 4 miles then quit. Any suggestions?

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When you say no illumination, are you speaking of the backlighting on the switch pods (headlight, wiper, console, legends around edge of touchscreen)? There are two high voltage inverters that supply 110VAC to illuminate the EL backlighting strips in the various switch pods. The 5 button console switch uses regular 12VDC bulbs. One inverter is in the console (near the lighter/ashtray under the trim bezel) the other is buried up inside the dash under the plastic trim top panel on tbe drivers side (near the VIN plate).

I rather suspect you have a bad photocell however (located under dash pad in dead center) as this detects whether it is dark enough outside to call for the intstrument panel backlighting to be on. There is a test in diagnostics under BCM inputs that will show the value being read by the photocell. A high value (typically 90-98) is darkness. If it is below 70 or so, typically the BCM will not turn on the instrument panel backlighting. A failed photocell will usually never read a high enough valuebto get these lights to turn on.

I have had to replace the photocell on both my 88's and will be doing so on my 91 convertible come spring. This cured the lack of panel backlighting both cases so far for me.

As far as the speedo loss, I suspect a bad line or connecter contact between the ECM and BCM. The VSS (speed sensor) output signal goes to the ECM first where it is then resent to the BCM for inclusion into the vehicle data stream that the IPC uses to display various operating parameters. The fact your other instrumentsa are working and your existing BCM/harness issues leaves me to think the VSS signal is being dropped before it makes it into the BCM. A bad VSS or associated wiring could also be in play however.

KDirk

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Guest jonate88

I will definitely try to test those things out but what i was referring to is the CRT i guess is the technical term. I can touch were the controls in every screen should be and they work (Radio controls, Fan Speed ect.) I just have no display. Also now that have the new bcm with my prom in it the interior lights work now but they stay on all the time, i had to pull the relay to get them to turn off.

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Guest Mc_Reatta

Proper terminology for the CRT is actually the Graphics Control Center, but we seem to stick with CRT and forget about the attached touch screen system. The CRT has the higher failure rate, the CRTC is necessary for the CRT to function but rarely goes bad. Your car seems to have been subject to some unusual conditions so normal failure modes may not apply. I'd start by cleaning the connectors on both units and see what happens. The two wire connector has the video signals, the other the power and touch screen signals etc. The fact the system responds to touch commands might make me lean more to a bad CRT not CRTC, but couldn't be sure without using the specialty tester that was made to test these units. The Central Power Supply (CPS) supplies the 12 volts to the CRT, so it too could be involved. Might check for voltages: 12 volts on a red wire with light blue stripe on CRT pin A1 from CPS measured against CPS ground on pins A2 black wire with tan stripe, and pin A8 black wire with light blue stripe. The wake up signal from the CRTC is on pin A6, another black wire with light blue stripe. There is a 5 volt signal from the CRTC on pin B8 (gray wire with red stripe), and its ground on pin B1 (black wire with orange stripe). Think that is part of the touch screen function.

post-55241-143142861862_thumb.jpg

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Guest jonate88

I am only getting 9.5 volts between the Red and Light blue wire and black and tan wire and 11 volts between the Red and light blue and Black and light blue. 4.3 Volts on Gray and Red, Black and Orange. Is that a sign it could be the cps?

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Guest Mc_Reatta

Don't think you would get any voltage if CPS was bad. Since all read low may be voltmeter. What does the battery voltage read?

Might want to follow wires back to CPS and clean those connectors too and see if voltage comes up some.

If you can manage it, you might try measuring for the video signal on the two wire coax connector going into the CRT. FSM doesn't indicate which of the wires is the video and which is the H sync though. So if you can set your meter up to measure at the lowest AC voltage setting your looking for a reading around 1 volt AC on one of the wires if the CRTC is sending a video signal to the CRT. The other wire won't show anything on a voltmeter.

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Guest jonate88

I am leaning towards just a bad CRT like you said. Everything else seems to be responding and working well. Does anyone have a good cheap place to get one? I'm on a tight budget. Thank everyone that has helped me get this piece of american history back to life.

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Eddie Voland in Westminster MD repairs CRT's His phone number is 443-536-9591 Several Reatta owners have used his services.

I had Eddy rebuild both my '89 original and a spare '89 CRT earlier this year and I was extremely pleased with his service. He worked for GM during the day when the Riv/Reatta/Trofeo had CRTs, doing refurbs on those units. He has all the equipment and knowledge and installs all the rolling upgrades that were incorporated during those years. At least when I had him rebuild mine, he was charging $150 per unit plus shipping. The only thing that he is NOT setup to handle, mainly due to the lack of availability, is the actual CRT tube, but those seldom fail.

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While on the topic of Mr. Voland, I should probably call him and inquire on replacing the tube. I purchased a few NOS tubes on ebay from REX Service a while back and was planning to swap them in myself. Since I have several units that need repair in storage, I wonder If he would do a tube swap provided I supplied the tube if I sent the units in for his normal rebuild service.

If he has the gear to service these and was involved in the project originally at GM, perhaps he can do the geometry correction procedures required on a new picture tube. This is not something I particularly want to tackle myself.

Not an immediate priority, year end expenses are stacking up here quickly....

KDirK

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