I have just purchased a '94Z....the check engine and ABS inop lights were illuminated...took it to a mechanic who was able to pull the codes from it. The car had been sitting for a few months without being driven. He told me that most likely the majority of the codes were from the car sitting and should work themselves out shortly, if they didnt, then we would need to re-visit...
Well, after 2 days of driving, the car seems much happier, and the lights are off, so is it possible that the car just needed to stretch its legs a bit? Below are the codes:

Engine: 42/48/61/64/22/91
ABS: 23/26/71/73/136

Help?

 

42 optispark circuit grounded
48 maf sensor
61 a/c system performance
64 right o2 sensor lean
22 tps signal voltage low
91 skip shift light

23 left rear wheel speed is zero or unreasonable
26 right wheel excessive variation
71 right front emb circuit
73 evo act circuit open
136 not listed

 

Check your ground connections with an ohm meter. I doubt the car has all of those problems. most likely a ground with GFS on it or a loose PCM connector.

 

Thanks for the advice all....I know some of the issues are genuine ones...the skip shift light is out, the AC needs a recharge, the car needs a new battery, so has low voltage...
Im not sure about a few of the codes, in terms of what they mean ,but thanks for the advice!

Anyone have any more info on what #71 and 73 really mean?

 

71 code 71 will set if a/c is requested and the pcm detects an open or short to ground in the evaporator temp sensor

73 pressure control sol. a pcm controlled sw to regulate transmission line pressure. pcm looks at tps voltage, engine rpm and other inputs to determe correct line pressure for a given load(weird is n't your a 6 sp) probbly due to low volts?

if you need any more troubleshooting info let me know, i have been working on lt1/4 vettes and camaros forever and have large resources. best of luck

 

The maf sensor and TPS voltage low codes are both a good indicator of a bad ground, even if the battery volatge was low the ECM regulates it down to a 5 volt refrence. Weather you have 10, 12, or 15 volts at your battery shouldn't matter. I'm sure you are still getting the 5 volt refrence unless you have a loose connector afrter the regulator, But a bad ground will cause the signal voltage to be low.
Check that first, then re-place the battery before you go any farther.

 

You guys really are great! More questions I havent turned a wrench in almost a decade, the last car I worked on was my '81 Z, so when I picked this car up, its a new world...

How's the best way for me to go rooting for bad grounds?
More specifically, grounds which could cause the codes listed....?

 

Well If you have a volt/ohm meter (If you dont have one you can get a decent one at radio shack for 30$. Dont go with the cheapest one, it sucks. The super small fold up one is good, I think its 39$.) put it on the ohms setting and touch the leads to both sides of the connection. (ie for a battery termanal place one lead on the terminal and one lead anywhere farther down the line where you can see exposed wire.) It wil give you the resistance of the wire in between. if its over 1 ohm loosen the connector clean both sides with baking soda and water (baking soda neutralizes). You can test whole circuits too. put one lead to the post where the ICM ground attaches, place the other on the - battery terminal. This tests the whole system, if you find a problem narrow it down. there should be a ground near the ignition control module on the left cylander head, one down by the starter, and mabye one more, and the negitve battery terminal itself. if you cant afford a muiltimeter all I can suggest is cleaning them all. Un-plug the battery - while you are doing the cleaning.
as far as i know the MAF and the TPS both ground at the ICM.

 

Multimeter I got I have a nice Fluke unit I work with daily

So tell me...this may be a stupid question...but what/where is the ICM?

 

Ignition control module, its right next to / below the mas air flow sensor/ mounted to the end of the head.