alero abs not working...

I have a 2000 Oldsmobile ALero Gl. I bought it with the ABS lights on on the dash. I brought it to a mechanic friend of mine who ran the codes on his computer and claimed it was the abs pump. I installed a new abs pump from the junkyard and had no luck, the lights remained on. So next I continuity tested all the wires that go to the wheel sensors as well as checked the resistance at each wheel to ensure that the wheel sensors are good. THe readings were as follows RF 1.05 K, LF 1.10 K, LR 1.11 K, and RR 1.00 K. All the wiring checked out from the sensor up to the computer terminal. After doing this I went and junkyarded an ABS Computer, by process of elimination i figured it made good sense to try this next. I installed that today and to my amazement the lights went off and the ABS and traction control functioned perfectly.

On my way home today however, (this is the first time driving it with the new abs computer) the stupid dash lights went on again and the abs no longer worked. I turned the car off, restarted it and it was fine again. I got another 20 miles down the road or so and the same thing happened again. Sure enough, turn it off and restart it and the problem goes away. My question is...

I have been told by a few mechanics (non gm people) that the ABS pump requires the use of a computer to properly bleed it. When I installed the pump I bled the brake lines at each wheel, that process worked fine and the pedal does not feel at all mushy. I went and asked a few gm mechanics if the abs pump did indeed need to be bled. ONe told me yes it did and the other said no and that it has its own self test bleed cycle and there is no need to do anything with it. Does the pump need to be bled? I am wondering if this is the cause of my lights coming on?

Also, is it possible that my main computer has some sort of glitch in it? WHere is the main car computer located? Any other possible explanations why the ABS is still not working properly? Please help me. THank you.

Welcome to AF!!

I really think your problem is one of the wheel sensors. It is probably going bad and it is causing the light to come on. Take it to the guy with the ABS capable scanner and have it scanned. It should tell you what is going on with the sensors. It could be a bad sensor or just a bad connector at one of the wheels.

Is there any possible way to tell for sure whether the sensor is bad without bringing it in? I checked the resistance across them (Did you see the newest popular mechanics magazine, they have a whole section on diagnosising abs). Does anyone have a repair manual specific to this car that they could tell me what the resistance is actually supposed to be? I am led to believe it is not a wiring issue, I continuity tested all the sensor wires as well as all the wires that go from the pump to the computer.

I did have it in at a mechanic who was the one that originally told to replace the abs pump. When we took it for a test drive one of the wheel sensors failed to read the speed for a split second, then it came back on again. So you think this is probably triggering it?

IS there any truth to the fact that the abs pump needs to be bled?

This forum is sweet btw!

Eliminate the wheel sensors by road testing with an abs scanner on the car and compare wheel speed inputs, they should be within 2 mph of each other pay particular attention at low speed, below 10. A lot of scanners pick up false codes and can throw you off track for a simple speed sensor issue, this test will confirm what is happening.

does the pump need to be bled?