mariojmoe

iTrader: (14)

2000 Z28, my Abs inop has been on since i purchased the car 3 years ago. I replaced the front and rear rotors and pads as well as both front wheel speed hub/sensors. Light still on brakes slightly better. Replaced master cylinder and abs pump. Still no dice, Ok my ?'s are 1) I think the abs pump I got from junk yard might have been a tcs car (idk) my car is a non tcs would this make a difference?, 2) how do I know how to identify a 3 or 4 channel abs pump? I call the salvage yards and they only ask if mine has tcs, no idea what a 3 or 4 channel is. I know my car has the rear sensor in the middle of the rear axle thus making it a 3 channel, which is the only sensor I have not replaced. Please help me with this very annoying issue thanx Mario

fast377

iTrader: (52)

You need to scan it and see what it says. A lot of different things can make the abs inop light come on. I just finished fighting abs issues. Mine ended up being the harness that goes from the center of the diff to the body. But without a scanner, you're going in blind. You could replace every speed sensor, and the abs module, and still never fix the problem.

mariojmoe

iTrader: (14)

Thanx fast lol I forgot to mentioned I had it scanned and it keeps reading right front sensor. I replaced that one twice with gm brand new wheel hub assemblies, and no go. The funny thing is its the rear left wheel that locks up under hard braking.

fast377

iTrader: (52)

When you had the scanner on it, did you just pull the codes, or did you drive it and see what each wheel speed was. Mine kept throwing a rear speed sensor code. After installing two of them, I decided to drive it with the scanner. It would intermittently drop to 0mph. Turned out to be a bad connection in that harness. If you have access to a gm service manual or alldata you can figure out which pins in the brake control module to hook up a volt meter to. Then wiggle your harness and see if you lose connection. You can do that with a scanner too.

mariojmoe

iTrader: (14)

Excellent, thanx bro. I'm going right now and try that, I'll let you know the results later, Much appreciated!

fast377

iTrader: (52)

Drive it in a parking lot while scanning. View ALL wheel speed sensors. Go straight for a bit, then make a couple of tight 180* turns. If you get wacky speeds, then it's probably a sensor or module. If you get no speed, or it drops to 0 every once in a while, it's probably a harness.

Good luck.

mariojmoe

iTrader: (14)

Ok just got back from just brakes and of coarse their scanner was inop at the time but I was advised to change the rear sensor then bring it in Monday and they will scan it no charge. I'll let you know the outcome, Thanx again fast.

fast377

iTrader: (52)

I still wouldn't buy any parts until you know what's wrong. That rear speed sensor is like $90 from gm.

socmguy

iTrader: (18)

ABS delete time!

mariojmoe

iTrader: (14)

Ok here's the latest, the shop said the computer is not reading or rather not communicating, and I'm pretty much screwed. My air bag light is also on (they never deployed) and I replaced the sensor under the center console. What is the deal with all of this??? Any advice is greatly appreciated. I'm really getting tired of this and will prolly just end up selling it.