Odometer Problem: Round 2

Ok, so today I received my EEPROM odometer chip back from prospeedo, and after reassembly, I am getting a 00 ERROR in the dash, with the "electrical problem" light on. Sorry for the sideways images and poor pictures.

But when I hit the test button on the IPC, the whole thing lights up just fine. The IPC is also less than a year old.

Also, the ECC head is blank, or showing the three dashes (---).

Does anyone have any idea on where I can go from here? If this is a prom problem, I can send it back and have them fix the issue, but I am just at a loss for now.

That sure looks like classic instrument panel outage. They will always light up when you hit the test button. And when you get 00/error, they knock out the climate control too.

Swap the panel from your convertible and see what happens.

Marck, I sure hope your right. The only odd thing about this is that the IPC was replaced right before I bought the car. I didn't think that these went bad too often.

Cold weather can zap em. Also if the battery isn't giving it's full voltage it can give the message. Was the car running?

Cold weather can zap em. Also if the battery isn't giving it's full voltage it can give the message. Was the car running?

No, the car was not running, and has not ran since about August. I was using a recently charged interstate battery.

So the cold weather can cause them to fail? Never knew that one... The dash in the convertible has always worked in this weather.

I would start the car and see what happens. Is it start able?

Can. Not will. Most of the time they hold up, but I sell a lot more electronic pars when the weather changes.

OR you could just have a bad or dirty connection.

The fact the ECC head is showing dashes along with the IPC 00/ERROR display is indicative of a data line fault. Could be the BCM, BCM PROM (not the odometer one, the other larger chip) one of the other modules on the line killing communications due to an internal failure, or the wiring for the data line could be shorted to voltage or ground. No data is making it to the ECC or IPC based on your stated symptoms.

Generally you don't loose both the IPC and the ECC due to an IPC failure but rather because of one of the problems I've listed above. If you have a spare good IPC you can swap and test but I don't expect that will solve your problem. You will have no access to on board diagnostics under these circumstances as the ECC has to be "on the line" to enter OBD.

KDirk

KDirk, everything was operating normally before the EEPROM was sent off for reprogramming. The only exception would be the code B556 and ERROR message. Would it be fair to say that the problem lies in the BCM or its PROMs? There was no evidence of a data line fault beforehand.

I will be back out working on it tomorrow morning, so any ideas are greatly appreciated.

Ok. A couple of things. First, a corrupted EEPROM (smaller chip that contains odometer and vehicle VIN and option programming) will render the odometer inoperative (and will generally read error in the odometer area) but will not affect the other gauges or operation of the climate control. This will cause a B556 code to read out as current in OBD.

The PROM (no EE) is the larger chip in the BCM that is also socketed. This is unique by model and year but not to the individual vehicle. Think of it as the operating system on a computer (like the copy of Windows or Mac-OS installed on the hard drive). If this is corrupted or damaged it will result in anything from intermittent malfunctions of BCM controlled devices (lights, power accessories and all instrumentation) or complete loss of functionality of any/all the above. Do your interior and outside lights work as they should? Security system? Do power accessories operate normally while in retained accessory power? These features can/will be adversely affected by a bad BCM or BCM PROM.

Since the BCM is also the bus-master device for the car's data network (meaning it controls the data bus and all devices connected to it in turn) all other modules that rely on the data line (IPC, ECC, A/C programmer, ECM primarily) generally require the BCM to be working correctly or the other devices (nodes in tech speak) will not see the data they need to operate normally. Sometimes this is catastropic (as in the IPC having nothing to show so it defaults to 00/error) or merely inconvenient (the ECM will operate on its own to keep the engine running with some caveats).

Since the last thing you worked on was the BCM (to install the new EEPROM) I'd start there. Make sure the BCM PROM is firmly seated in the socket. Make sure all 3 BCM connectors to the vehicle harness are plugged correctly. Manipulate the individual wires to the three connectors to see if any are not making good contact.

The possibility also exists that you may have zapped the BCM with electrostatic discharge while putting in the new EEPROM. The modules on the Reatta use a lot of CMOS chips that are particularly sensitive to ESD damage. If this turns out to be the case, a replacement BCM will be required. Needless to say, the two PROMS from your current BCM would need to be transferred to the replacement.

If none of the simple things above remedy the problem and you are sure the BCM and it's PROM are good then you'll need to start the troubleshooting tree in the FSM for data loss errors as that appears to be your root problem based upon the described symptoms. That is the only proper way to isolate and determine the specific point of failure so it can be correctly repaired instead of taking wild guesses and swapping parts in the hope it will clear up.

While there is a chance that some other failure occurred by sheer coincidence (stranger things have happened) there is much greater reason to suspect a BCM related fault as that was the last component worked on and it is central to the issues you are now having.

KDirk

I just finished checking a few things on the 91. Here's what I have so far:

-I have no interior lights, but outside lights are OK. No fog lights, but the fog light switch lights up as it should.

-I have fully functioning anti-theft. Both horns blow and both fog lights flash. (Bad fog light switch I am assuming.)

-I do not believe that RAP works at the moment because the Radio was non operational except with key on/run.

-All power features (i.e. windows, mirrors, door locks) work correctly, and locks work correctly with keyless entry.

-Both PROMs are seated correctly with no room for play, and the connections are good with no room for play. Moving the wires in the harnesses does nothing.

I will start looking at the data line failure trees in the FSM for any leads.

Any other ideas from what I have here?

Ok, I may have this thing solved. I reviewed the FSM for data line failures and began testing starting at the beginning of section 8D - Computer system diagnosis. I began with chart B and when I had no courtesy lights, went to chart B1 on 8D-35. According to the chart, I probed 1C8 and 2B1 on the BCM to get a voltage reading, and found it to be at about 50 volts, as opposed to the 10 volts that it needed. All of the connections are good, so I am gearing up to replace the BCM.

Ok, that's progress. 50 volts though? That seems...not quite right. I would add that the power windows, locks and RKE operate independently of the BCM. The interior courtesy lights are under control of the BCM so it your findings seem to point to a BCM failure. Hopefully neither PROM has been damaged by the failed BCM.

KDirk

Yep, 50 volts. I have a little analog voltmeter that I used, and 50 is the highest readable level on the meter. I hope the PROMS weren't damaged either.

I have already taken the BCM and dropped it off at Auto zone to have it remanufactured.

Just a follow up to this: I just got my BCM back from autozone. The label said that the builder could not rebuild the computer, so for now, I am down a BCM. The only positive was that they refunded me the price for repairs.

Does anyone on here have a 91 BCM?

Just checked eBay for a BCM and snagged one for $20. It says that it came from a 92 Toronado Trofeo. The part # is 16137944 with AYTH chip, not that I need the chip, as I still have my original AWAC chip.

Not bad for $20, just hoping that it will solve my issues.

Can't tell much without seeing the .bin (EEPROM contents) but since you have more than one '90 you could swap the whole BCM and see if the trouble follows. Same for the instrument cluster.

If it follows the BCM, next swap the EEPROM (the little one, right ?). Once you narrow it down can go from there but currently there are at least three possible culprits.

I have a 90 Reatta Coupe with dash light problems. They are intermittent. When I get in if the mileage shows on the dash the instrument panel works fine with all gauges functioning as they should. If not showing I get the 00--error message with Electrical problem down at the bottom left. What's odd is that I can be driving with it not working and all of a sudden it will light up as it should and work fine for a while. Other times when it's working, it will drop off with the Error message and stay that way for a period of time. Then when I start it the next time it may work fine. Any ideas on why it works intermittently? The mileage keeps functioning, ie, going up, when the dash is not working. All interior lights work as do headlights and I don't sense any other problems. Just puzzling to me. Any suggestions on what to check? At one time I did pull a breaker in the panel down by the drivers legs to check to see why horn wasn't working. After that the problem started and I did replace the breaker with a new one but it didn't help. Help

ChuckRe, fear you have some failing solder joints inside your IPC which is one commen failure mode of the 90s panels. Before getting a replacement or rebuild though, pull the IPC and clean and inspect the connectors and reinstall it. The intermittent connection might just be there, and not internal to the unit.

Here's some reference material fron Ronnie's site:

http://reattaowner.com/roj/component/content/article/61-electrical-system/digital-dash-panel-a-crt/214-dashboard-reads-00-error-90-91-models

http://reattaowner.com/roj/component/content/article/61-electrical-system/digital-dash-panel-a-crt/215-digital-dash-panel-ipc-removal-90-91-models

I just got a used BCM out of a 92 Toronado off of eBay in today. Swapped both chips over and tried it. There was no difference, still 00 ERROR on the dash and (---) in the ECC. I made extra sure that everything was seated properly and that I didn't accidentally shock anything, and still I get the same result.

I am running out of ideas here...If the issue is not with the BCM, could it be in the PROMS? I received both proms with the new (used) BCM. The chip is an AYTH. I will check tomorrow using the chips from the other BCM.

I see two possibilities. First, one or both PROMS were damaged by the faulty BCM and now aren't working in the replacement. Second, there may also be a data line problem between the BCM and IPC, and the PROMS may or may not be bad.

The PROMS that came in the BCM won't work as they are from a Toronado. While it is a similar car - E platform - the body control system and instrumentation are coded differently in firmware between the two cars. So, there is no telling what unpredictable results (if it works at all) you'll get trying those PROMS in a Reatta.

I don't think you'll damage anything trying the PROMS from the Toronado but neither do I think they will work enough to determine anything certain on what is still wrong.

Are you getting any instrumentation at all (speedo, volts, temp, oil, etc.)? Are other body systems (interior lights) security system (when triggered, do fog lights blink and horn sound) interior lights delay on exit, RAP functions and such work as expected? If they do then perhaps the main PROM is ok, but the lack of display on the ECC concerns me. Ordinarily, the climate control head will work even if the odometer is corrupted as long as the data line is intact and the BCM and main PROM are good. That brings us back to either a data line problem or a bad PROM. Actually, are you certain the BCM you purchased is good? Was it tested and sold as good?

Additionally, are the connecter shells on the BCM the same color as the corresponding plugs on the vehicle side harness? I can't say for certain the 1992 E platform BCM is the same as used in 1991. I don't think they would have changed it, but have no experience with 1992 model year E platform cars versus 1991 (of which I own two) so can't vouch first hand for any differences in that regard.

KDirk

KDirk, thank you for your comment. Here are some answers to your questions.

I have no gages or instrumentation, just the 00 ERROR message as if the IPC was bad.

Interior lights do not work.

RAP does not work.

The security system works properly with horns blaring and fog lights flashing. My fog light switch does not work but I was aware of that.

The color coded connector shells are the proper color of Red and Brown.

The BCM was a tested and working unit from a running Toronado.

Could this mean that my BCM PROM was fried by my original failed BCM? If so, where could I find an AWAC PROM?

Starting to sound more like a bad BCM PROM based symptoms on your last post. Funny the security system works, I'd thought the fog lamps at least would be non-functional but the security controller must operate them directly rather than via the BCM. Now I need to look at the schematic.

As far as a new AWAC PROM, that is one I haven't dumped to the computer yet. Been meaning to, but it will mean pulling the BCM from one of my 91's. I suppose I need to do that now, and I could make a new one for you. I may have time this weekend, weather permitting, to pull the BCM on my 91 coupe and do that. Of course, if you manage to find one elsewhere sooner, that's fine too. I still need to copy the PROM as one of my long range projects is to have ROM images of all major PROMS used in Reatta modules for all four model years archived.

KDirk

KDirk, if it isn't too much trouble, could you make a chip for me? I can send the AYTH chip to you if you need something to write over. Send me a PM if you need things sent to you.

Also, I really appreciate all the help and diagnostic information that you, and everyone else has offered here.

Brett,

No need to send the AYTH chip. I will use a fresh blank 28C256 EEPROM as the originals require a special UV light chamber to erase, and due to age they tend not to take new data reliably in my experience. The blank chips are not particularly costly (a few bucks each in bulk) and I have a supply on hand.

That said, all I can send is the chip, it will not be in the protective plastic carrier shell as I have no spares. If you'd like me to install it in the carrier, then you'd need to send it to me so I can remove the old chip and put the new one in it before sending it back. If you would prefer that then PM me here and we will make arrangements.

KDirk

The problem has been SOLVED. :D:D

Well, at least discovered. I put my AWAC chip in with the spare odometer EEPROM and the IPC and ECC lit up just like normal. I can guess that whatever prospeedo did with my original EEPROM was interrupting the data line.

Here are some pictures with the other EEPROM installed:

Interesting. So the 92 Toronado EEPROM (black socket) works in the Reatta and shows mileage, etc? I wouldn't have thought that would work. Of course your odometer will reflect the mileage of the donor car, and the VIN (if checked with a scan tool) will be wrong. At least you are up and running for now.

I'd be contacting pro-speedo for a refund or a redo of the EEPROM at this point.

KDirk

I just contacted prospeedo, and they will be redoing the odometer chip for free. So hopefully everything will be squared away soon.

I really appreciate all of the advice and technical know how shared in this thread!

Looks like you may have a bad oil pressure sensor.

Looks like you may have a bad oil pressure sensor.

I believe you are right. If I remember right, it is located around the oil filter. Pretty easy fix compared to what I just dealt with.

And either zero gas or a bad fuel sending unit.

And either zero gas or a bad fuel sending unit.

Bad sending unit/float I bet. I had 5 gallons of gas put in when I parked it. The person who had it before me (a dealer) replaced the fuel pump, and probably messed up the float while it was out.

Have seen some fuel senders heal with use, the windings are exposed and a little varnish goes a long way.

Just got but chips back from being redone (again). I tried them both and neither of them work now. :mad: This is pretty frustrating, and now I'm out of options. Where do I go from here? (Other than getting my money back of course)

Did you disconnect the battery before plugging the new EEPROM in? I ask because in experimenting on my own car I have concluded that the BCM contains a RAM memory that holds a copy of the current odometer reading and will write it to the EEPROM on insertion if it isn't cleared first by disconnecting the battery. This appears to be a bit of a failsafe so that if the EEPROM is temporarily not addressable the cumulative mileage (or last known good number+what is currently on the trip odometer) is maintained in RAM then updated into the EEPROM when it can be written to again.

"Hot plugging" when the BCM is powered may corrupt the EEPROM contents. That is about the only other idea I can offer at this point.

KDirk

Yes, I always disconnect the battery before working with the EEPROM or any electronic components.

Ok, then we can likely rule out damage to the BCM or EEPROM from hot plugging. Now at the risj of beating a dead horse, have you swapped in the IPC from the other car to see if it is an intermittent problem with that? If not I would make that the next step so it can be ruled out. The fewer variables the better. Once that is done then maybe there will be some other flash of brilliance from which to proceed. Otherwise, I have to suspect either a bogus EEPROM (still) or maybe a faulty BCM. I've had thr same component defective back to back more than once, so don't rule that possibility out.

KDirk

Ok, so after making sure the EEPROM was properly seated, I managed to get back all of my gauges with the exception of the odometer. I have a working IPC and ECC now. I guess I didn't have the chip seated all the way after all. I also tried using my original BCM, and found it to be good too. I must really be terrible with electronics and computer stuff. Here below is what I have now.

BUT, I still have ERROR in the odometer slot, and a code B556c. I am still assuming the EEPROM is not good. (Both EEPROMs cause ERROR in the odo. area)

Also, a question: I know that the EEPROM season odometer information has to match up with a checksum value. So, could it be possible that when the person I sent the chip to only accounted for the mileage correction and not considered the checksum value not matching with the season odometer information? If so, what would need to happen to that value in order for the chip to display mileage instead of ERROR?

Glad you made some progress. Here is what I can tell you about the odometer as stored in the EEPROM. Based on my own car after dumping the EEROM there are two data segments of 6 bytes each. Each of the two segments are completely different, so I assume one is the mileage and the second is either a checksum calculated from the mileage value and some other value by an encryption formula or a second copy of the mileage encrypted differently than the first. Neither segment can be directly translated to the odoemeter reading; each is encoded by some means. Presumably if the BCM looks at both 6 byte values and sees a mismatch based on the expected encryption then it shows "error". I do know that each segment changes as the odometer changes. I dumped the EEPROM contents of my 91 coupe at a given mileage, reinstalled it and drove 1 mile. Dumped it again and noted the changes. Repeated this process for increments of 2 miles and 5 miles and can see the values change but still have no solid understanding of the encryption algorithm.

I'd say it is relatively secure, yet not that sophisticated given the age of the vehicle and the relative difficulty of accessing the EEPROM contents as very few people will have had the hardware to do this in the late 80's and probably not many more do so now. I'm sure with enough time and thought I'll figure it out. Of course, once done, it is not the sort of knowledge I'll be comfortable sharing openly as I have no intention of making the odometer easy to hack for those with less than honest intentions.

All that said, it will be nice to know just for my own satisfaction. Whether or not I can apply that knowledge, once gained, will be a tough call. I could help someone out of a jam, but unless I know beyond any doubt I'm not contributing to a case of odometer fraud, there is no way I'd consider burning a chip for anyone other than myself.

So there is what I know as of right now. All of which really does nothing to assist with the problem at hand other than to offer some technical insight.

KDirk

I am happy to finally post a resolution. After multiple attempts to fix the ERROR in the odometer, I can say that it is finally repaired! Now on to the other issues! New tires will be mounted soon!