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dash electrical problem


Retired w/Reatta
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I was driving up the beautiful Columbia River Gorge to take my mother-in-law out to lunch for Mother's Day.  I'd been driving about a half hour when the blower fan went to high, the lights went out on the climate control and the radio (although the tape continued to work I couldn't control the heater, or turn it off); the speedometer went to 0, flipped all the way up to 158, then back to 0 and stayed there; the odometer also stopped.

I cleaned and tightened the battery and ground cables.  Replaced the climate control and the IPC.  Still the same.

I brought it to my local garage and they couldn't figure it out either.

Any help would be greatly appreciated.

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Yes.  When I cleaned the ground connections I disconnected the battery and also cleaned and greased the battery connections.  I have the battery out now to clean the connections at the electronics ground block and the fusible links, although these connections look clean and tight.

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This is a guess, have you checked the power supply fuse? I pulled mine out by accident and while car was running and what you described, for the most part. Lost entire instrument panel, AC, Radio, maybe more. Fuse is 10 amp drivers side top right. After reading your failure mode again this is probably not the problem, however it is easy to check.

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  • 4 weeks later...

Fast forward a couple of months.   I went down to northern California to visit friends for a while. On the way I got a BCM from a 1990 Riviera.

I also bought a used and tested good BCM.  I put my proms into the used/tested BCM and now I get the dreaded code E026.  Not only that but now when I start the car it will run for a minute or two, then the RPM's will dip and peak and then the car stalls.

I checked the vacuum lines, they all look ok.  I scrolled through EO01 to EO10; I could hear clicks from the solenoids and relays except for EO07-canister purge solenoid.  Fuel filter was recently replaced.

Could the MAF be the culprit?

Thanks in advance for any help.

S.

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Yeah, i'd try some MAF cleaner to start with. i had a similar problem with idle all over the place and that took care of it.

 

if it doesn't, take a look at the canister. there is a recent thread that has a great pic of it provided by "Machiner 55". :)  some vacuum hoses that can't be seen unless the air cleaner isn't taken off.

 

after all that, let us know if anything fixed her. if not, then there could be other "suspects"... ;)

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post-78374-0-14583300-1434071829_thumb.jpost-78374-0-95836900-1434071846_thumb.jI cleaned the MAF but to no avail.  I took your advice and removed the air cleaner and I found a corroded vacuum line.  The corroded line was at one end of a T and was a cap off; it came apart in my hand.  Tomorrow I'll go to my FLAPS to get some vacuum hose.  I take it this is a cruise control connection as one end of the T comes from the servo and the other end goes to the dash.  Why is one end blocked?

Thanks,

S.

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a) one end is blocked because it is also used with a normal power brake in the Riviera.

  B) If leaking both the cruise will not work properly and you may not be able to control the HVAC vents (defaults to "defrost").

 

How do you turen off smileys ? that was supposed to be b ) without the space.

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I was wondering why it defaulted to "defrost".  I thought my ECC was bad that's why I replaced it.

Now I'm beginning to wonder if there ever was anything wrong with my BCM, I'm going to switch it back and see.

Anyway I replaced the vacuum cap on the T, car started up great, ran good for about 10 minutes (about 9 minutes more than before) then the RPMs went bonkers and it stalled.

Could I be looking at another vacuum leak?

O2 sensor?

Thanks,

S.

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OK.  I reinstalled my original BCM and it didn't seem to make a difference.

I removed , cleaned, and reinstalled the IAC (it wasn't that dirty).

I ordered an O2 sensor from Ronnie's Store and installed it today. Ronnie your site is great; you make it so easy to buy parts at good prices.  Thank you.

So I start up the car.  It runs great for a few minutes, then the RPMs go bonkers and the car stalls.

It appears as if it may still be a vacuum leak.  I looked in the FSM but couldn't find a diagram of the vacuum lines.  Does one exist?

Am I missing something?

Thanks,

S.

ps. Brenda (Cargirl), I want you to know I am devastated that I am not your "best friend" anymore, but as long as I'm replaced by a Reattaphile, I think I can handle it.  Thank you for my 15 minutes of fame!

Corvanti; I couldn't find the post by "Machiner 55"  re the canister; could you please be more specific.

Thanks,

S.

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Thanks for using the Reatta Store. I appreciate it..

 

The vacuum lines on the Reatta are pretty simple. I don't have a diagram. The likely spot you are going to find a vacuum leak in the lines is where the lines come together near the cruise control and vacuum canister. Both are located on the  driver's side inner fender panel. That is where I found the lines rotted due to age on my car.

 

Also check the short rubber lines on top of the throttle body where they attach to steel lines. Several people have had them crack and break. You can see them just to the left of the EGR in the photo.

post-95476-0-81212700-1434609628_thumb.j

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I have checked all of the vacuum lines and all appear to be ok.

I replaced the O2 sensor.

I've tried different BCMs.

Car runs for a couple of seconds, then stalls.

Also, when I open either door, all the interior lights come on as usual, but the fog light also come on!? Huh?

Still searching,

S.

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If the fog lights are lighting with the door(s) open, double check your BCM option content. I ran into this once when swapping in a used BCM from a Riviera (and using the PROM that was in it). The foglights illuminated with the doors open, and discovered that reprogramming the option content to match the car (Reatta in this case) stopped that from occuring. Apparently the BCM output used for fog lights on the Reatta is used for another purpose (courtesy lamps?) on a Riviera and when not programmed for the correct car, still enables that output based on what car it "thinks" it is in. Section 8D of the FSM covers this, and there are three option content parameters that can be changed.

Now, there may be other possible causes of this problem but I wanted to mention this since it is not likely to be something you'd usually think about when troubleshooting. It may be your BCM EEPROM is corrupted which can cause several unpredictable problems. Killing the engine is not one (unless it is related to the security system somehow) but need to start somewhere and the engine problem may well be coincidental and unrelated.

Edit to add: reading back to the first post, I wonder if symptom that caused loss of instruments may have sligtly corrupted the BCM EEPROM. If there was a write to the PROM in progress when the system went offline, it may well have written extraneous bits that are now causing unpredictable behavior. Usually this would set a BCM code, but even the best hardware self-checks are not fail-proof.

KDirk

Edited by KDirk (see edit history)
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Thank you Kevin.  That sounds very plausible if not a bit overwhelming.

I recently got two codes: E023 (manifold air temperature sensor circuit) and B552 (BCM keep alive memory error).  After clearing, the E023 code disappeared; the B552 comes back.

I have been reading much of chapters 8D and 8A.

If I have time tonight I will pull my proms and install the ones that came with the used/tested unit.  I also have a BCM from a '90 Riviera I pulled a long time ago.  I'll see if anything changes.

Is the larger of the two proms in the BCM the one you refer to as BCM EEPROM?

We're leaving tomorrow for two weeks in New England to visit family, friends and to enjoy a wedding so my sleuthing will have to wait for a while.

Thanks,

S.

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The B552 error is set anytime power is removed from the BCM (generally the battery being disconnected, or if the BCM was removed from the car). If it is showing as current (not just history) every time you run the car, you have a problem with the always live circuit that supplies battery voltage to the BCM, or less likely, the BCM itself.

Regarding PROMS: the BCM contains two. One is a calibrator PROM (or EPROM with one E) that holds the program for the year and model of car it is intended for. Generally, the Reatta and Riviera of the same year would share this same chip. This is the physically larger of the two chips and has 28 pins total (14 per side). The smaller one is an EEPROM (two E's) and has 24 pins (12 per side). This one is unique to each car built as it contains the VIN, factory option content information and the odometer reading. It is updated with the current odometer each time the car is turned off. While the car is running, the main odometer (and trip odometer as well) is held in RAM memory within the BCM. When the ignition is shut off, the BCM copies the current odometer value into the EEPROM before powering down in order to preserve the correct mileage even if power to the BCM is lost and the RAM is wiped. Then, this value is loaded back into the BCM RAM on subsequent startup of the car and passed along to the instrument cluster for display.

The EEPROM can be damaged or corrupted by malfunction of the BCM, loss of power to the BCM during a write cycle, or static discharge from handling. Sometimes this corruption is minor and can be corrected by the car itself by writing correct data back into the chip later. The odometer for instance is held in three different locations within the chip for redundancy and uses checksums to verify data integrity. The damaage can also be bad enough to be unrecoverable without puliing the chip and rewriting it with a special programming rig made for that purpose. Generally if this happens, you will get "ERROR"in tbe odometer display and an electrical malfunction indicator as well as a BCM EEPROM error code set. However, the severity of the problem can vary as well as the resulting malfunctions and errors that result.

You can substitute the EEPROM from the 90 Riviera to test but remember it will have the wrong VIN, mileage and option programming. You can change the option bit settings to reflect the correct values for a Reatta from inside diagnostics but of course cannot change the VIN or odometer without special tools.

Doing this would at least verify the functioning of your BCM and associated hardware. Just don't drive it around this way or you will compromise the integrity of your odometer as any miles accrued will be written to the substitute EEPROM while installed, and lost when the original is reinstalled.

I will look later tonight and see what the correct values for a 1990 Reatta are for option bits 1, 2 and 3 and post them here so you can verify and reprogram them to correct values if needed.

KDirk

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I think you should start a new thread just for the stalling issue to keep it separated from BCM issues. I don't believe the BCM will cause the engine to stall or keep it from starting but it might be possible. I would think the ECM would be able to keep the engine running, at least in limp home mode, if the BCM failed.

 

When you are ready to troubleshoot the stalling issue you need to get back to the basics of determining if you have an ignition problem or a fuel supply problem when the engine will not run. Once you know that you can proceed with finding the component that is failing resulting in the engine stalling.

 

I've been planning on doing a How-To guide on the basic steps that are needed when troubleshooting an engine that will not start. My free time in the Summer months is limited so I've not got started on it yet. Besides that it's just too damn hot here in Tennessee to be under the hood of a car right now. :)  In the meantime I will be happy to assist with finding the problem if I can.

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Ok, was a bit delayed in posting this but had to unbury my 1990 FSM. The option content parameters for a 1990 Reatta for US (not Canadian or other export) use is as follows:

Option 1 (BS06): 144

Option 2 (BS07): 228

Check these in diagnostics via BCM overrides and see what values are stored. If they do not match these numbers, they need to be reprogrammed and saved to insure the BCM is properly configured for the car.

KDirk

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  • 2 weeks later...

We had a wonderful trip to the colonies during the July 4th holiday.  But it feels good to be home.

I reinstalled my "original" BCM (I discovered it has a remanufactured sticker on it) with my proms.

I reprogrammed option 1 (B506) to 144 (it read 0):  option 2 (B507) to 228 (it read 130).

This appears to have chased away the gremlins; foglights, defroster, dash.

Thank you all for your help and Kevin thank you; I now know so much more of how this great car functions it makes me appreciate it and this forum, that much more..

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