Sworn

Hi guy's. I could use some help with a few trouble codes I pulled from my C4. In a previous thread I mentioned some issues I've been having with my ASR coming on despite being turned off. In winter, I've been storing the car at work which makes things even more challenging when it comes to diagnosing problems. Well today I finally had some time to pull the codes and this is what came up....

1) H72, H74
4) H28
9) H65

I searched the web and came up with a few things, but want to make sure I'm right. That being said, what do these codes stand for?

Thanks in advance!

Sworn

BTW it's a 1992 MY...

JimLentz

Here is a great place for use as a reference to the codes. They are all history codes, so you could try clearing them by disconnecting the battery for a few minutes. I have a theory that your ECM is having issues as my ASR seemed really sensitive when mine was intermittently failing. I also had some odd codes and a couple of times the car would start and die two seconds later. Another issue related to the ECM I had was the A/C starting to blow warm until I restarted the car. I sent my ECM to SIA Electronics with a list of the symptoms and trouble codes and for less than $200 they repaired it and sent it back to me. If you go that route be sure to remove the MEMCAL from the ECM before sending it in.

WVZR-1

Quite sure he can't clear CCM and ASR/ABS by disconnecting the battery. The code 28 hints ECM but he's mentioned ASR/ABS specific so you clear CCM and ASR/ABS using the DIC. I posted this for the later 16 pin DLC connector a couple weeks ago. Maybe I'll try to do the same for '92 & '93.

This should be correct likely for '92 & '93. This is all 10 pages related to CCM diagnostics I believe.

JimLentz - how about 'proof reading' the file. You've a '92 I think.


92 Chevrolet Corvette SM(1133-1143)_1.pdf

Sworn

Thanks for the info guy's!

To further elaborate the issue I'm having....I was mistaken in my initial summary. I thought it was flashing ASR ACTIVE but in reality it was projecting ABS ACTIVE. So now, armed with this information I clearly believe it to be an ABS issue.

I drove the car home from work last night and back this morning. I now seem to have a better understanding as to what's happening. The ABS seems to be kicking in every so often on acceleration. It doesn't do it all the time but sure is annoying when it does. I also noticed it comes on about 3 MPH. To be clear, this is under normal light acceleration, not spirited driving.

With the above listed and more accurate description, anybody have any ideas? I also checked the brake fluid level the other day and it was within operating spec....

As always, thanks in advance!

Pa'svette

I had a similar problem on a 04 Tahoe. I found a GM service bulletin that said there is a problem with cars in the rust belt ( Ill. Ohio, Mi. ect.) when road salt corrodes the hubs where the wheel speed sensors mount. The fix was to remove the sensor, clean the mounting surface and reinstall.
On the Tahoe the ABS light would come on when you hit a bump and when stopping (below 3 MPH).
May be the same on your Vette.

Sworn

Thanks for the reply! Since you mentioned it, I noticed in my particular situation it would come on about 3MPH. Very similar indeed!

Dropped it off at another mechanic today so we'll see. Definitely will bring this up!

Sworn

I was told the wheel speed sensor is shot. Apparently it's not an easy part to locate....

Sworn

Okay, all of you that have replaced the rear abs sensor, where did you get it???!!! Apparently it's a discontinued GM part and nobody seems to carry it!

ecorti95

It is better to disconnect the connectors from the ECM before pushing in the wires to the connectors.