Help! Resolved

[Anothersteveg]

So I finished up my cam install/dod delete and with the Pat G tune it's running great!

Problem is, as soon as I started it after the install, I'm getting an ABS/Traction Control off/Brake light. It was intermittent a couple starts, now is on constantly. I took it to the auto parts place, they scanned it and showed C0121 Valve relay error. I've done the obvious and looked for lines I may have disconnected and cleaned the connections but nothing. What did I do during the install that might have caused this? Anybody have anything similar? What can I check from here?

Thanks!

Steve

[Kermit]

Crap, I'm not sure what to look for on that. Have you ensured that all your grounding connections are good and tight?

[Napalm]

how long did the car sit? how solid is the battery?

theory one - weak battery voltage on startup will cause odd system failures during startup test. SOme of those systems set persistent codes. ABS/Stability is one of those. It's feasible that the values were cycled on initialization and one stopped shot due to a voltage drop. Because it failed startup test it sets a persistent code.

Have you cleared the codes and it comes back immediately?

Theory 2 - if it clears and comes back then I have to say you probably have a bad ABS controller - that is internal. YOu could try to flush the system with clean fluid and see if a reset causes it to come back again. I don't know that would work but it might. If you had a tech 2 you could work the individual valves in the module and do a full check - I don't know if other scanners will do that as it requires sending specific CAN codes into the system. This by the way is the same thing done for the factory flush job as called per the manual - IE with pressure pot you open and flutter each valve individually during a full brake system flush.


Look for places that rebuild the modules - you need to start with it's part number. I'm afraid ours are a bit unique but there are placed that rebuild the ABS modules for a reasonable price. New cars like the CTSV and vettes and have systems that also have the brake force distribution like our car does - but they have different part numbers that I know of. I am afriad however your module is broken and would have to be rebuilt or replaced.

[Anothersteveg]

Ok, thank you for the replies. It's a strange one because I can't for the life of me think what I would have done to catch any of the wires, they don't really run near anything I dealt with on the swap. I'm going to get back under it tomorrow and look one last time then go and get the code reset again. The battery was a little low and it sat for a little while so that's a great thought about the random codes. I've run it some now and the battery was new this summer so it should be totally charged up now.

Hard to believe it's just a strange coincidence but I'm beginning to think that's it.

[Napalm]

well you might not have caught a wire but you might have bumped it and jostled something out of kilter. I also doubt that but it would be a possibility.

still think it's a start up concern. OH IIRC you can pull the ABS fuse and the comm fuse under the hood and that would replicate a reset. since the module would fully power out.

I might be wrong about that but it's something I'd try - or a battery cable pull for some 30 minutes plus. OH and check your cold battery voltage. IE not started - sat over night - DC volts at the battery terminal. should be 11.5-12.5 ish.

anything under 10.5 and I'd say your battery lost a cell. Anytime I get a code or light I always check electrical mains first. (fuses and relays - battery voltage)


hell fixed my wife's aunt's ford edge the other day. had issue saying the key fob just never seemed to work. Wouldn't unlock the doors without being right on top of the car - sometimes has to use the key etc etc. fob battery was new . . . so I metered the fob - figured new battery might not be new. played with the car a bit - flash the lights, lock and un lock the doors etc. then I do as I suggested - check the mains. Car battery voltage sitting over night was under 10.

new car battery - bickety bam - unlock the doors from 20ft away inside the house. Oh and the car started better - but you know she didn't bother to tell me that the first time.

[EricL9]

I had (and am still having) the same issue(s) after my cam install. My ABS, Traction Control and Airbag lights all came on. I have a feeling the ABS and Traction Control are linked issues. I need to check all the ABS sensor connections and wires to make sure they're not corroded, which I've heard is a common problem. The airbag issue could be the dreaded bad module under my passenger seat. All of this happened when I got the car back from getting the cam installed. Like you said, it sounds like an odd coincidence, but it could be just that. A coincidence. And it likely is. Good luck tracking down the issue. Keep us posted here. You're obviously not the only one this has happen to.

[Anothersteveg]

Does anybody know - if I replace the ABS module does it need to be reprogrammed?

[Napalm]

I don't have a shop manual but I don't beleive it needs to be programed - but it does need to be bleed - and your whole brake system bleed.

and doing that correctly does require a Tech2 or equivalent (like the snapon too or ________).

as you have to flutter the values while pressure pot bleeding the system - as I mentioned earlier.

[Anothersteveg]

Fixed it! Went over all the wiring again and everything I touched was bueno. I did happen to notice a connector that didn't look right. Sure enough the male prong had backed out. It wasn't one I had disconnected during the swap, but while moving the harness I must have made it come loose. Strange because none of the wires go to the ABS module or any of the sensors.

I'll post a picture just in case it helps you Eric. Thanks for the input everyone.

Steve

[Anothersteveg]

27025

[Anothersteveg]

27026

[Anothersteveg]

27027

[Kermit]

Glad you figured it out Steve. :first:

[Napalm]

damn - good find.

what does that harness go to? I assume the BCM but just curious.