zeke2u

I have an '03 Z06 that sat quite a while with a dead battery. I get the P1571 H C, TCS No Comm, and SDM U1040 H C codes. Also, my ABS is not working. Does this mean that the EBCM is toast? If so, why would a dead battery cause the failure? Lastly, is there a reasonable source for EBCM's?

00Vette04GTO

Bill Curlee (spelling?) is the man in these forums you really need to talk to... Really good chance it is just a serialization issue. (still new to vettes but had one myself)

There are STAR jumpers in your passenger side floorboard that connect your different computers. I could tell you what to unhook and where but it would be the blind leading the blind - a shot in the dark.

Also, to verify - have you tried resetting the codes? They could be stored from when the battery went dead - and are no longer an issue. (ignoring the ABS not working)

Ultra_Miner

One day out of the blue I had those similar codes. I did the ignition switch clean up. I had a couple of burnt contacts. Cleaned them up and those codes went away. I had the sdm 1040 code and rear defogger open circuit code, and the no coms tcs. I used Bill's write up on cleaning the ignition switch. 03 Z06 here also.

zeke2u

00Vette)4GTO - Yes, I've reset them and they returned. There were other codes present, which didn't return. Now, only the 3 codes listed at the top return. I've checked the 2 grounds at both front frame rails - there was no visible corrosion (my eyes are almost 65 years aged) but I did lightly rub some 400-E Norton (made in USA) abrasive paper across the washer connections and pins, along with a shot of WD40. I haven't checked the data connectors at the EBCM or PCM - but will do after I type this and another cup of Joe....

zeke2u

Ultra Miner - Did you have ABS lights on the dash, too? Would a 25k vehicle need to have it's ignition switch checked and cleaned!!!?...

00Vette04GTO

Ultra miner is also on the right track with the switch contacts. Bill has a great writeup on that (test before cleaning - unless you just have free time to kill) - though I don't have a link to it on me. I do have all the fuses to check for voltage written down on a piece of paper if you can't find his post. (sure someone has the link on hand to post here)

zeke2u

00Vette04GT0 - Was your ABS light on the dash?

00Vette04GTO

No... My car actually would not start at all due to the seat module being de-serialized. But according to Bill it can cause anything from weird indicator lights, communication issues, and all the way to a no start situation.

You having a dead battery + the communication issues + ABS was making me think along the serialization lines.... But contacts in these cars are well known to go bad in the ignition switches - which will cause different computers to get different voltages - and all kinds of issues.

zeke2u

Well, I took apart the data connectors and saw no anomalies - gave a squirt of WD40 into both genders. Still getting the 3 codes. Maybe I'll pull the ignition switch. I have the service manual and will go read for a while.....

Bill Dearborn

I wouldn't use WD40 to do that. It leaves a coating that may cause issues later on. Use a proper electrical contact cleaner. It is available from any auto parts store. Look for CRC QD Electrical Contact Cleaner Aerosol.


Bill

Ultra_Miner

Yes my abs light came on also. Mine Z only had 40,000 miles on it when the lights and codes just appeared one morning. I didn't fix it for a couple days. Sometimes it would just start with out the codes or light or weird other codes, it freaked me out.
Like I said it was out of the blue. I tried charging my battery and it seemed to help a little. I believe it seemed to help because the battery had a good charge and could get the required voltage across the burnt contacts in the switch. I would suggest cleaning the ignition switch. I even had the dreaded Service Column lock issue a few months before, I did the LMC5 bypass for that and it worked for that message, but I believe the burnt ignition switch contacts brought that issue to the fore front, low voltage passing thru the switch.
It's not hard to follow the ignition switch clean up by Bill. Since cleaning up the ignition switch she's been running great. No codes anymore. It's not the miles that matter for the switch, it's the number of on off cycles that cause arcing on the ignition switch contacts. I had 3 burnt contacts.

zeke2u

Thanks Bill Dearborn and Ultra Miner. I'll remove all the connectors that got sprayed with WD40, clean them with alcohol, and give them a shot with the CRC product. And, I guess I should have pulled the ignition switch when I removed the console and IP to install my C6 shifter. I'll be bringing the Z to the state police, today, to have my salvage title inspection. Hopefully, they wont give me a hard time with the ABS and "Service Vehicle Soon" messages on the dash...I wont have time to pull the ignition switch before the inspection. Perhaps when I return, hopefully, with a "passed inspection"....