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abs, trac light, abs self test noise

H

hitnf

New member
Hi all,

2007 GP base

I checked the other posts

http://www.grandprixforums.net/threads/105274-Traction-control-turns-on-when-entering-and-leaving-parking-spaces
http://www.grandprixforums.net/threads/105834-Trac-Brake-ABS-lights-on-C0050-and-C0095

The abs self test pump activates once after a short distance of driving. Aftera longer drive, it engaged a few times then the abs service light and tractionlight came on. Shut off the car turn it back, went away then came back. Readonline sometimes it glitches.
Its coming on regularly now, and sometimes before the lights come on, doing aregular stop the brake pedal pulsates, like the abs activating at low speedthen the lights come on. Both the abs and traction control don't work.

tried a regular obd ii scanner can't scan the codes, has to be abs scanner,checked brake fluid level its okay.
Read online that sometimes its the contacts of the speed sensors, or wiresfrayed going to the wheel hubs sensor integrated into the hub .
Sometimes its the wheel hub.

It could also one day taking the wheels off and examining the wiresclosely even disconnecting the connectors and applying grease if we have any.
Could look at the abs control module connector.

Last year we changed the tie rod ends and the driver side front wheelhub.

other thing, when we put the summer tires on, one of the sensors wasn't readingprobably due to low battery as its the originals on there.
The tire pressure sensor light turned on, just like in winter time so that'sokay. But now I notice that is not coming on, only the abs and service light, now the tire pressure light is on too.

it seems to be very hard to come by a scanner that can scan the abs codes. Unless anyone has any ideas please.

thank you
 


Watch the wheel speed sensors (4 of them) while driving. My guess is one will drop out momentarily causing your abs to fire up. That's where to look for bad wire or hub.


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Had same problem awhile ago with car running I started to wiggle wire harness until abs traction control came on. It was my wire harness front right ordered a new one from parts geek replaced about 2 feet of harness good luck
 
you can watch each wheel speed signal with a scan tool but if the system is setting a code, get the code read and go from there.
these old vehicles use passive wheel speed sensors, they are ok at speed but the signal strength weakens the slower the wheel turns, this may cause signal fallout...the ebcm sees this as wheel slip and activates the abs system...resulting is a false abs event...typically, this happens at parking lot speeds.

read the code to isolate the problem sensor.
unplug the sensor and ohm check the sensor (not the harness to the ebcm) it should ohm approx 800 -1300 ohms iirc (find the spec). its its out of spec, replace the hub assembly
set your ohm meter to a/c volts...spin the tire by hand...its should generate an a/c voltage or 0.1 volts or higher...the faster its spins, the higher the voltage. If both those are ok
-disconnect the ebcm connector and ohm check the wires from the ebcm to the wheel speed sensor harness.
 


Hey Bud get an abs scan it will give you a better idea whats going on and save your self a lot of money before you start changing wheel bearings advance or pep boys might have an abs code reader you can use
 
Sorry for the delay, thank you Daviddawg, Spazzz, and Markpa. Very useful information to check with the voltmeter, and the scanner. I did inquire locally for a scan, but the places I contacted wanted to charge. We managed to remove the wheel and saw that one of the wires was frayed on the wheel bearing connector. The shop charged labour for it, just about under warranty and charged for a bracket. It maybe came on once since then maybe as a fluke, but so far seems okay.

https://drive.google.com/open?id=1BxyxLPEu9cBvMAXrXTk_qFQqGgQjoA_s

Thanks
 
So just an update, I had a local garage, tell me bearing needed changing in the front, and I would still have the light come on and their scanner showed it was the bearing again. They changed it again, and costed some money. The light would still come on at random when turning.

abs_wires.jpg - Google Drive

I managed to check the wiring and the one of the wires were frayed going to the bearing. I had help to solder it in. I ended up buying the Dorman 970-047 harness.


Thank you all for your help.
 
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