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ABS Module , How to bleed?


regalfriend
02-12-2007, 12:12 AM
I have a 97.5 GS. My right rear brake pad was low and i drove on it for a while. It grinded metal to metal. I didnt care as much since i usually replace the rotors every brake change..... The brake pad grinded so low that the whole pad fell out. When i hit the brakes it was the cylinder from the caliper grinding on the rotor. This caused damage to the cylinder and caused a leak. I lost fluid and got air in the whole system. I replaced the RR rotor, caliper, pads and bled only the RR brake. After that the pedal was high and the car stopped good. I know since i got air in the whole system that all 4 calipers should be bled, as well as the ABS module. I heard that there is a special machine that does this? My ABS, SVS, and Trac off have been on for a while before this happened. I think i need a new hub. I know that if i bleed the brakes that it will not turn off the ABS lights etc and i wont have ABS anyway. My problem w/ the hub is that I dont know wich 1 is bad. I know OBD wont tell me wich one is bad. ONLY tech 1 or Tech 2 will tell me. I cant afford a dealer to diagnose this....Also when i got a flat tire the low tire light did come on...Is this because this system works off the hub?

BNaylor
02-13-2007, 05:45 AM
The low tire pressure monitor system works off the same wheel sensors in the hub just like ABS and traction control. It could be a bad hub, wiring or even an EBTCM module. If you have that much air the brakes you might consider getting them bled done by a pro.

Check the resistance of each wheel sensor with a DMM. Around 1K ohms and the wiring especially the electrical connector at the back of the hub.

regalfriend
02-15-2007, 04:33 PM
Thanks Bob. I know there is still some air in the system. Since i bled the rear caliper the pedal is pretty high. The car stops good. The pedal does feel a little spongy. I went to GoodYear for tires and asked if he could bleed the entire system. He said he could for $123.00. My question to him was if he had a machine that is used on the ABS solenoid. He said it's not needed that you can just open the bleeder valve and bleed it like that. Is that true? If it was old school type brakes I would bleed it myself. In this case I will have a pro do it. He also ran a OBD2 scan and told me the front right hub was bad. I thought OBD wont be specific as to wich hub is bad. I thought you need Tech 1 or 2 to tell which hub is bad?

BNaylor
02-15-2007, 05:15 PM
Actually bleeding ABS braking systems is similar to the old conventional method. Unless the ABS modulator or master cylinder were replaced you could just bleed air out normally at each caliper using the gravity method. But a certain sequence should be followed. For GM ABS VI systems:

RR, LF, LR, RF

On scanners your high end ones like the Snap On MT-2500 and other similar can check ABS wheel sensors so a Tech I/II is not needed. But at least you pin pointed which hub/wheel sensor is bad so thats good news.

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