So the ABS light came on. I noticed that the abs started to activate at slow speeds over a bumpy road and pulsating the front left wheel. Then after a right turn, the ABS light comes on. It goes out after restarting the engine. Then the same sequence seems to trigger the ABS light on again. Brakes work OK just no abs after the light turns on.


I did the rear pads, rotors, and shocks a couple of weeks ago. I pulled the rear wheels to check the sensor rings and they seem OK. I did have the emergency brake cable rubbing on the left rear hub - it wore a smooth line on the hub but did not seem to damage the sensor blocks. Maybe dust affected sensor? I pulled the front left wheel, seemed OK also. Any thoughts or diagnostic tips would be much appreciated.


thanks!

 

John, based on what you are describing, I would be looking at the ABS sensor wiring behind the front passenger wheel. It is very possible that with the wheel turned, the wiring is coming in contact with something and it is grounding out. I would also think that if you pull up the codes for your car, you should be getting either a C1145 or a C1155 code. This will also help to prove that the problem is associated with a given wheel.

I would do a good detailed inspection of the wiring for the front passenger wheel. But, the problem technically could be on any one of the wheels. This is where pulling the codes for the car will help narrow down which wheel the car is seeing as being a problem. But, what you describe sounds like a wiring issue, not so much a sensor issue.

 

Thanks Thermo - I will look at the wiring more closely. The scanner I have does not read any codes(at least C codes just P1000), also the system resets after each start so not sure if it is stores the code.


john

 

Bad front wheel bearings could be the problem, as they wear when you turn the wheel fully one way or the other the spindle tilts slightly away from the reluctor ring and this causes the sensor to lose signal.

I'd start there first. Pretty easy to check, take the front wheels off, turn the wheel fully each way and look closely between the brake rotor and caliper mounting bracket to see if the gap between the rotor and caliper on each side is the same, if not it's time for new wheel bearings.

 

ok guys - checked the bearings - no gaps and were tight. I checked the wiring and connections for the front sensors. the right side seemed loose - I pulled apart and clicked in place. Test drove and still had original symptoms. I then pulled the drivers side. The drivers side was tight, however after checking the connections for this side the abs and CEL lights came on almost immediately, even as I was shifting the car into gear. I cleared the CEL. Still no P codes were pulled. I will ask my mechanic cousin who has a $1500 snap on OBDII reader to pull codes before I start changing parts. what fun....


as always thanks for the help!

 

Thermo you were spot on. Pulled codes and it is an open right sensor circuit fault. I will be testing the wires and sensor and will update. Thanks.

 

Found some time to diagnose it today. I tested continuity of the wiring harness between the sensor and connector under the wheel well. One of the wires did not check out. I removed the harness and tested again, and after jostling the wire where it makes a U-bend, the wire made contact, so it is a broken wire in the harness assembly. I ordered a used wiring harness for $22, now just have to wait for it to come from across the pond!

 

John, good to hear that you got things figured out. Those intermittent problems that are a broken wire inside the insulation can be a bear to figure out where the problem lies.