Evening guys. Picked up a ‘03 Z with 22k miles. Only mod is the skip shift jumper. Original tires. Car still smells new inside. Couldn’t be happier. Had an ‘02 Z 10 years ago and bought a new FRC in 2000, so not my first corvette. Backstory here….guy I bought the car from didn’t drive it much at all obviously. He had it posted and we made a deal. He went out to do an in car cold startup video for me and the Service Traction Control display popped up. First time ever. He is a perfectionist like myself, and wouldn’t sell me the car without this being repaired. I told him about ABSFixer, and he sent the module out to Brandon for repair. Got it back, installed it, and display was gone upon starting the car. Fixed.
Drove down a few days later, picked up the car and drove it almost 200 miles home, without issue. A couple days later, drove the car about 40 miles without issue. A few days later, started the car and the ABS light came on, and display says service car soon. Same day, a few hours later, the display reads Service Traction Control. Drove the car today and the dash light went away for a few minutes, then came back on…went out a while later, and came back eventually.
I wanted to get some thoughts from you guys here. Brandon has rave reviews and knows his stuff, from what I’ve found, so I don’t think the module has crapped the bed again. Here’s the current codes shown. Brandon erased all previous codes.
99-HVAC B0361 H C
28-TCS NO COMM
40-BCM NO CODES
10-PCM P1571 H C
60-IPC U1040 H
58-SDM U1040 H C

Thoughts?

 

All your DTC's except for the HVAV B0361 point to the EBCM...The IPC isn't able to communicate with the EBCM with the U1040...you sure the SDM U code is a U1040 ??...for ANY "No Comm" you the first thing that needs to be checked is that modules power and grounds...was that done before sending the EBCM out for repair ??...your profile says your an electrical contractor so you should know how to use a DVOM...below is the EBCM wiring for my 01...see if the wire colors match up...if not we will have to look at an 03....remove the connector and see if you have battery voltage on pin A which is hot at all times and with key ON pin B should have battery voltage. always a good idea to do a "wiggle test" when checking each wire. Now the best way to check the grounds is with an old headlight bulb assembly...go to the autoparts store and get yourself a 60 watt bulb that has the wires on it (below) and use that..to check the ground you can use pin A to each of the 3 grounds highlighted...if the ground is good the bulb will be bright...if not you will have to check the body ground for that module !!..I would also check for loose or bent pins and terminals !!

 

Yes sir, U1040. Working on this today, I’ve found the negative side batt cable is loose and won’t tighten up…might be the entire problem? I’ll report back.

 

You can purchase these shims if they don't tighten up !!

 

Negative side battery repaired and still has no comm displayed. I don’t see your wiring diagram above. Really appreciate the help here guys!

 

Now this is out of my 01 FSM…if wiring doesn’t match up we will have to get an 03 connector diagram !!

 

Here is 03 schematics , looks similar to the 01 drawings

 

Thanks guys! I’ll post up what I find.

 

I have verified that I have 12.24 volts at terminal A. Terminal B is same with key on. Terminals F & G both have good ground according to my Mac Tools test light.
Battery voltage is 12.24 and dips to 10.16 volts as starter is turning engine over… Battery is a year old and is a 700 cold, 875 @ 32 degrees, 120 reserve capacity Duralast battery. I don’t like anything AutoZone personally, but I didn’t buy the battery. It came with the car. I bought this Z on the 25th of last month.

 

Should I test pin 13 to verify hot as well? I’m ASSuming low reference is referring to ground?

 

No !!…pin 13 (low ref) is a ground…like I said best to check with headlight bulb but a 12 volt test light connected to either battery positive or pin A if you have one..test light only draws 1/2 amp at the most…even with a ground key needs to be ON to check !!

 

Yes, low reference is referring to a ground. I’ll check it also.

 

Ok, pin 13 does not read as a ground. Verified wire is orange/black stripe. With red lead of my Fluke77 on pin A, which is verified hot, pin 13 will not ground it.

 

Not sure the module had a problem to start with. Brandons’ report says (seller gave it to me along with another module he had) that he removed solder from previous repair (not a ABSFix) from daughter board and bench tested it. Tested fine. Doesn’t say anything about a relay changeout, or anything else wrong. Test drove module on a test car he has for 20 miles and it was fine. It goes on to say if problem persists, check battery connection and voltage.
I could be wrong, certainly wouldn’t be the first time…

 

You using the voltmeter function of your Fluke ??…if pin 13 was a good ground you would see battery voltage when connected to pin A…what do you see ??

 

Nothing. Display on Fluke continues to jump around as it does when connected to nothing. As if pin 13 doesn’t exist. Key was on in car.
edit…just realized I grabbed my Fox meter out of my tool box, instead of my Fluke. Doesn’t matter, just throwing it out there.

 

See if you have ground at Pin 13 of the EBCM module itself and not at the connector !!

 

Ill have to put this on hold for a few days. The Z is in the basement and it will have to go out to my shop any go on my lift for me to see the pins. My Chevelle is currently on the lift and I won’t move the Chevelle outside while raining. It’s gonna rain here til Wednesday some time. We have baseball practice Wednesday and a game Thursday. I work a lot of hours, so it might be next weekend, but I’ll be back. Appreciate all the help so far folks!

 

Ok, had a dry spell here so I got the car to where I could see the pins. Man this thing is in a bad spot there. Anyhoo, pin 13 is definitely a ground. My battery voltage today is 11.94 volts. Could this just be a battery issue, or would the no-comm override the volts?

 

Don't know if you used a voltmeter or a bulb to check ground but if you checked it at the EBCM and it was good all your EBCM power and grounds are good...11.94 is pretty much dead !!...don't know if maybe the key was on for a while but it's best to check anyway...you may have a parasitic drain going on...do you know how to diagnose that ??...if not I can send you a YouTube video...easy to do !!!...do you have a battery tender or a charger ???