Hey all, I hope I’m posting this is the right place to find the most knowledgeable people to help. Here’s the deal: I have the following current codes along with “service engine soon” on the DIC, and check engine, traction control, and ABS light illuminated:

2002 Base C5 coupe, manual trans, Auto climate control.

In 10-PCM: P1571 ASR Desired Torque, and P1689 ???? (Can’t find this code description anywhere)

in 40-BCM: B0432 Rear Defogger relay circuit

In 58-SDM: U1040 Loss of communication with TCS


Here are the recent related events I’ve noticed:

I’ve noticed that the analog voltage gauge needle on the dash seems to take a while to reach proper voltage upon startup. (The digital readout in the DIC reads proper voltage) As the needle is coming up, I get all the warnings and lights in the systems mentioned above. Almost as though they’re not getting the power needed to “pass all their tests“ upon startup.

I’ve noticed more recently that when the warning lights are all on, the HVAC system (its an Auto HVAC, not manual system) will not work.

Sometimes if I start the car and get all the warnings, I can turn it off, immediately restart it, and everything will reset and be fine.

One time, when the warning lights were on, and the HVAC was not working, I tested the systems by braking hard (ABS did not function and I locked it up) and accelerating hard (traction control and ASR did not function and spun the tires) and confirmed that, as designed, these systems were off when the warning lights were on. Funny thing was, right after I did that (about a minute), suddenly the warning lights went off, and my HVAC system immediately came back to life, and all systems functioned properly. Then everything was 100% fine the rest of my drive until the next day when I started the car again.



Things to note that may be related:

I’ve had the alternator rebuilt. It is the original one still.

I recently (a few months ago) sent out my EBCM to ABS Fixer to have it rebuilt, and it’s been fine. These problems are similar to why I had it rebuilt, but not the same. That was the common C1214 error code, and that hasn’t come back.

There is a relatively recent new battery in the car as well. I replaced that when I rebuilt the alternator.

I drive the car almost every day, so it does not sit long enough to discharge the battery from not being used.



As listed above, I know what the code descriptions are except for P1689. I wasn’t able to find the description for that one. Anyone know?

So has anyone ever seen this combination of codes? I find it very strange and can’t figure out the common factor between them all. I’m thinking maybe the alternator needs to be done again? It seems like some sort of loss of power, but that’s just a guess.

I am a pretty decent home garage mechanic, I’m not afraid to take things apart, and I try to learn and gather as much information as possible. But I am not a professional mechanic and there are many things that are over my pay grade. Electronics are not my forte and when it comes to circuit testing and such things I’m not the best. But I can definitely take out and replace an alternator, water pump, ebcm, valve seals, suspension parts, etc. That kind of stuff I can do. So I’m hoping someone can lead me in a direction which leads to a fix I’m able to do myself. We will see.


Thank you to anyone who has read to this point and is willing to help!!! I look forward to any responses. Thanks again!

 

Also, I should add that when running the codes in the DIC in the 28-TCS and 99-HVAC modules it showed NO COMM. I do not know if maybe it should be communicating with those modules and perhaps the fact that it’s not is indicative of part of the issue...?

Thanks again to anyone who may be able to help figure this out.

 

https://www.corvetteforum.com/forums...000-vette.html Info on 1689.

 

Make sure you check your ignition switch. I had many similar issues, but no codes. After much work, an ignition switch cured all. You may have more than one problem. Good luck.