My 94 z28's abs light is on on the dash. I know the basic purpose of abs systems but not familiar with troubleshooting. It's on steady and not flashing if that helps. Brakesare functioning properlyfor now.I've done some basic visual checks like b/fluid level, elect. connections at the controller, and a quick front pad wear check. I've noticed that the abs relayin the fuse box looks similar to the a/c relay. Can I swap it to see if my relay is bad or are they different? Any other checks I can do myself b4 taking to the dealer?

Another thing I'd like to mention and it may be unrelated to the issue abovebut my car has always displayed a low voltage on the v/meter in the dash. I've never gotten higher than 12.2 volts. I've had this car about 2 years now with no starting problems what so ever. But ever since the ABS inop light has come on voltage is at 11.3 v. fully loaded with lights and a/c on. I've checked alt connections as well as body grounds. Thanks for any replies.

Mike

 

Is the abs working at all though? You could always check by finding a slippery or gravel road and mashing the brakes real good to see if they lock up or not. Ofcourse the way you describe it makes it sound like more is going on what with the low voltage and what not. Now when you say you check the connections and ground do you mean just visualy or did you make sure the alternator and charging system is working properly??

 

Its your alternator. Mine was on its last leg voltage so low that my lights all but shut off, my guages went hay wire and at a full stop my speedometer said i was doing like 50 mph. I bought a new autolite and its all perfect now.

 

get the car scaned with a abs scanner. for the abs its prolly a wheel speed sensor. you can also take your battery and alternator up to auto zone to see if those are bad too.

 

If you don't have one, go to Radio Shack and buy a cheap ($20) volt or multimeter. With the engine running check the voltage across the battery terminal. On a good system the voltage should be be between 13.8 to 14 volts. Turn on all the accessories, lights, AC, radio, etc. Bring the RPM up to around 2000, voltage should not drop below 13.5 volt. Problem could be a weak alternator or a sick battery. The weal alternator can lead to a sick battery.

 

ok. Let me help you cut all the red tape, give you the two easiest ways to find out. Turn your car on, turn on ur a/c turn on your stereo and turn on your lights now disconnect your negative cable from your battery. If the car dies then your alternator is shot and you need a new one. Why? because the alternator should power EVERYTHING when the car is on.. thats its whole purpose.. the battery charges things when the engine is off and when the engine is on the alternator recharges the battery and powers your accessories. Now the 2nd easiest thing would be to go to autozone and having them check your diode read out... but you run the risk of not having enough power to get back lol. Thats the easiest way to find out. And its free....

 

Listen to this guy.

 

Thank you.. lol... especially since i just had the same thing happen to me and i put this theory to the test and what do you know.. it worked... now i have a new alternator and my problems are solved.

Basically your battery is only used to start the car, the alternator should do the rest. Thats why alot of drag cars jump start their cars to get em going because they dont have a battery they rely on the alternator alone.

 

Spart, I think I'll do your second test because I was taught never to do the ole remove the neg cable while runningwith an ecm car. What was explained to me is that ecm and alt needs reference voltage and sudden removal may cause the alt to spike voltage and cause all kinds of other failures. Now I thinkyour technique has been done by many many people with good success but I'm alittle uneasy about it so I'll still do your plan B.I understand that the abs inop can indicate a very inexpensive to very costly repair so I'll take one step at a time and recheck the obvious and cross my fingers. Thanks for everyones input, all is very appreciated.

 

ight man. Just thought id let you know that i did it and it and it proved successful and i was able to reconnect the neg cable and drive off two seconds later to buy a new alternator.. Then again i had my diode tested later as a back up.