bigpigdave

I'm doing free 20 point inspections (tires, belts, hoses, fluids, etc..) along with allowing the customer to follow along, many don't know how to look at these simple items and are wanting to learn. it doesn't tie my bays up for long and allows me to point out how my service differs from their current shop if they are not already a customer.

Dave

Dave's Shop

-Power & Machine-

Camden IN

A few weeks back a customer came in complaining that, at times, when he applies the brakes lightly the ABS would come on. He was sure that he was on firm ground, not skidding. We dispatched the job to one our diag techs. He performed his routine visual inspection and then hooked up the scanner for a road test. The tech clearly observed, thru the scanner, that the left front signal was dropping out at times. Having seen countless issues with GM wheel bearing/hub/ABS components, he advised the service writer to order a new wheel hub.

 

After the new part was installed, the tech performs a final road test only to find that the problem is still there. Is it a defective part? After reviewing the process, I instructed the tech to hook a scope right to the left wheel sensor and monitor the signal at the wheel and also monitor what the computer was seeing. Sure enough, the signal at the wheel never faulted, but the computer was seeing something else.

 

We opened up the harness, which is fastened to the suspension, and found a tiny break in the harness which was flexing when the brakes were applied. A new left side ABS harness fixed the problem.

 

The lesson: Never assume; when we see pattern failures over and over again, it can lead us down the wrong path. Always stick to the basics.

How did you charge the customer? Did you reinstall the original wheel bearing/ sensor assy.? Did you charge for the incorrect diagnosis time? I always have trouble with this type of situation as I don't feel ok charging the customer for what I believe is my mistaken diagnosis.

Dave