Pontiac G8 Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
1,366 Posts
Discussion Starter #1 (Edited)
On another thread I discuss my traction control issues. After following a good lead from GOPHERIT (Thanks !!) I finally got to the real fix.

First... the symptoms:
Traction control activation warnings under normal driving.
Traction control system shut down (occasional)
ABS kickback under mild braking while turning
ABS shut down (occasional)
And then more recently a thrumming or throbbing sound from right rear on smooth pavement.

First my mechanic read the code: right rear wheel speed sensor. We replaced it...no change in symptoms.
Then I changed the wheel speed wiring harness (advice from this board, cheap, easy, might be the fix)... no change
Finally.....REAR WHEEL BEARINGS. They contain a wheel speed encoder ring (or tone ring) that can go bad.
All symptoms disappeared !! Cool. Thanks again GOPHERIT !! I owe you.
 

·
Registered
Joined
·
2,001 Posts
So it was the hub bearing like I said. lol
 

·
Registered
Joined
·
1,366 Posts
Discussion Starter #3
Haha...... well wait... you actually said "hub sensor" !! It was not the sensor, it was the encoder. So I can't give you full credit. GOPHERIT was a bit more precise in saying it was the encoder.

I also learned how the system works... magnetic induction, just like a guitar pickup.
 

·
Premium Member
Joined
·
4,668 Posts
Good your issue got resolved and will bear in mind this information for future reference. Appreciate the update.
 

·
Registered
Joined
·
1,366 Posts
Discussion Starter #5
It is awesome having my car back and drivable with no technical issues............fun !!!
 

·
Registered
Joined
·
2,001 Posts
Damn. Should have been more specific. That's what I get for posting from my phone at work. lol
 

·
Registered
Joined
·
1,521 Posts
Isn't the ring that the sensor reads off just a metal piece with teeth?

I'm trying to understand how exactly it was the problem. ie... it was damaged by having 1 or more teeth broken off. If there are little magnets on it, some of those fell off etc...?
 

·
Premium Member
Joined
·
4,200 Posts
^^^^^ I can only visualize that there would be (something like a large washer type thing) embedded withing the bearing itself. An that *it* has X number of raised segments near the outer edge surface of the bearing itself. The outer part of the bearing (pressed into the hub) rotates at the speed of the hub. As each raised segment pass's by the stationary sensor mounted in the knuckle, it causes the sensor to send out a pulsed voltage signal back to the EBCM (thinking a *HALL* effect circuit). Since "jbak" stated that his mechanic found that the bearing basically fell out of the hub (upon inspection), along with a *now* wiped out hub bearing mounting cavity, maybe the encoder ring was *now* no longer in its proper position to have those segments pass by the sensor as it should. The loss of that WS sensor signal from that RR location, for sure would cause the system to fault itself (an probably blaming the sensor as the cause). If there is some visual look to the bearing (that might actually show segments spaced around the outer bearing surface), maybe "jbak" can post a pic of his old bearing. I for one, would like to see what it looks like.
 

·
Registered
Joined
·
28 Posts
I just started getting ABS/ESC faults popping up this past month. It would happen every time I broke the tires loose then would reset after a key cycle. I hooked up the Tech2 and it said left rear wheel speed sensor. I wiggled the plug into the left rear hub and it made the fault come on immediately at startup. I figured it would be in my best interest to fix it before the winter hits here.

Solution:
I unplugged the connector at the left rear hub/wheel speed sensor, cleaned the pins, crammed some di-electric grease in the pin holes and plugged it back in. No issues at all now, in dry warm days, or wet cold days. Saved me a bunch of $ not having to replace the hub or wire harness.
 

·
CCG8 Member
Joined
·
1,599 Posts
Isn't the ring that the sensor reads off just a metal piece with teeth?

I'm trying to understand how exactly it was the problem. ie... it was damaged by having 1 or more teeth broken off. If there are little magnets on it, some of those fell off etc...?
It's in the bearing, when the bearing goes it shifts around and stops reading.
 

·
Registered
Joined
·
1,366 Posts
Discussion Starter #11
To be more clear... After a while I realized the warning only came on when turning RIGHT. AND the ABS kickback was felt when turning RIGHT. There must have been "play" in the bearing as it was going bad, and under a right turn load the ring moved a bit too far from the magnet (sensor) to induce a proper signal. So the wheel speed was read incorrectly and the system tried to correct a non-existent slide or wheel lock.

It all makes sense now that I know how the system is configured. Like my tuner said: This problem will crop up more and more as miles accumulate on these cars.
 
1 - 11 of 11 Posts
Top