April 19

2003 Chevrolet Impala – ABS Wiring Harness Replacement

Auto Repair, Chevrolet


Our latest featured post delves into an ABS Wiring Harness Replacement on a 2003 Chevrolet Impala, brought to us by a client from UBC, Vancouver.

Chevrolet Impala
2003 Chevrolet Impala. A full size GM car that first came into production in 1958.

ABS brakes have been pretty much standard equipment for a decade. While there has been some argument over whether they are truly effective and offer better better braking than a seasoned, skilled driver, the fact that they are found on almost all cars and especially on all high end cars indicates that they are a worthwhile safety feature.

Sophisticated electronics make ABS brake operation possible. There are sensors at each wheel informing the ABS computer of each wheel’s exact speed. From this data the computer can adjust the vehicle’s braking in fractions of a second.

Obviously inaccurate data creates problems. The ABS computer also monitors the sensor’s circuit voltages and resistances and if something is out of range, it will switch on a dash warning light and usually shut down ABS brake operation. This doesn’t mean that your brakes won’t work: they will operate just like normal non-ABS brakes.

Our featured Chevrolet Impala came to us with some strange brake operation at low speed stops and the ABS  and TRAC warning lights on intermittently. Diagnosis found a trouble code for the right front wheel speed sensor. The sensor had been replaced recently at another shop but this had not solved the concern. We tested the sensor with a lab scope and verified that it was good.

Looking further at the wiring we found that the wiring harness to the sensor had been repaired with a butt splice connector. Butt splice connectors usually make a very poor wiring repair and one that can lead to many problems. They are ill-suited for repairs on sensitive electronic circuits. Good wiring and proper connections are essential to flawless ABS operation. This was the cause of our client’s concern. Fortunately a replacement wiring harness to the right front wheel speed sensor was readily available. After repairs the light stayed out and the brakes worked flawlessly.

For more about the Chevrolet Impala please view this link http://en.wikipedia.org/wiki/Chevrolet_Impala

For more about ABS brakes click here http://goo.gl/zMKPbH

Chevrolet Impala
Damaged ABS wiring harness. The red arrow points to the butt splice connector. The blue arrow point to the plastic sheathing over the wires, this was cut back for the repair. The plastic was also very hard and would not allow flexibility. This may have caused the wires to break in other places.




About the author 

Bernie Pawlik

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