My ABS/ASR light is on. I pulled codes as follows; Module #1 DTC74 Module #4 nothing, Module #9 DTC72 and 83. My question is, my car is a 93 vett. 6 spd. The FM shows no DTC74 or 83 so what is up with that? And it also shows DTC72 as "gear selector switch circuit" for automatic tranny, so how can that be? No codes related to the ABS/ASR at all, any ideas?
I believe module 9 is what controls the ABS right?

yes... but the ABS error codes are listed either under the ABS chapter or with the CCM, not engine codes.

It's called the EBCM - Electronic Brake Control Module.

Let's see what these codes mean...

72 is a serial data link error... means it didn't or isn't getting info from the CCM.

83 is low brake fluid.

Bogus you are right it's with the ABS section. I'll see what I can find there, thanks!

Any thoughts about the 74 from module #1, I checked the prom with my tuning program and the switch for the Auto/Manual tranny is switched to Manual, why then would I get this error code? How is that possible?

Quote:
Mod 1 (CCM ) DTC 74 :LED display dimming output circuit open or shorted to ground

http://www.corvetteforum.net/c4/dave8476/index4.shtml

Kinda slow working on this but I cleared all codes and only the 83 came back after driving. The FSM says to check the fluid level switch for 5 ohms or less, it shows 3. So it says to replace, ordered one today and will see if that fixes the ABS.

cool!

I have an 86 so the abs system is different than yours I think but I found something that might relate.
After getting mine out from the winter sleep, I was getting an intermittent ABS light coming on. Unforunately not alot on this one in the manual but I checked all I could. Then I removed the front brakes, compressing the caliper to get them off and the ABS light came on solid and stayed on, feared the worst.

Thing was the pump seemed to cycle and the brakes were solid and no issues actually found relating to braking.
Next had the SES light come one solid and stayed on, made no sense. This was the first year for ABS so little relating to codes plus it's ODB1.

Poking around the web found a thread that said if the battery was down or the alternator was failing (alternator and battery were replaced in the last couple of years), it could trigger first the ABS then the SES lights. Well I just ran the car about 15-20 minutes a month while in winter storage, so I got my battery charger out and did a trickle charge on the battery over night.

Next day, fired it up and both lights were out and have not returned.

Don't know if it will help, but worth a check or trying as it's easy and basically cost free.

hcbph thanks for the comments, hopefully I can replace the fluid level swith today and see if that fixes it. My ABS has quit working so I would like to get it back.

ABS is fixed!!! It was the fluid level sensor/switch in the master cylinder. Amazing O'Rilley auto had one in stock for $14.00. Really these cars are pretty amazing for 20+yr old technology. The car can tell you what is wrong and if you have the Factory manual (a bit cumbersome and very awkward to use yet very good for diagnosing problems) you can do a lot yourself. Thanks for the help.

awesome!!!