Problem with truck repair or just venting

[eliallen]

Took truck in for ABS light, Mechanic , scan codes identified Rt front  speed sensor. He replaced it. About 600 miles down the road ABS light came on again. Got back home and had my neighborhood mechanic scan the codes, Codes indicated RT front speed sensor bad. He knew that it was just replaced. So he calls his friend at the  GM dealer. Friend told him to replace the wheel bearing (came with a new speed sensor.) You probably guessed it by now, yep, the Abs light still comes on. He gave me a bill, which I paid, thinking that he would take care of the problem. Nothing yet after 3 days. What would you expect the mechanic to do? Could I win in small claims court. I really don't want to sue. Last mechanic owns the shop, and a long time friend (20 years).

 

[Gary RV_Wizard]

Have you discussed the problem with him and asked what, if anything, he plans to do to solve the problem? I think 3 days is a bit premature to talk about suing somebody.

Mechanical repairs are generally held to be done on a "best effort" basis, meaning the action is deemed valid & reasonable as long as it is what a typical mechanic would do in the same situation.  There is no guarantee that any given action will be the final solution, nor are such parts and services refundable.  Since there was a clear indication from the diagnostic code and he sought additional confirmation form another mechanic, I think any court would conclude his attempt was reasonable and justified.

 

[eliallen]

Interesting. My bad , it was 6 days ago. The GM Shop he called after he replaced the wheel bearing said that they never had a issue like that. I called another GM shop to get an appointment, and explained everything that was done and what was told to me.  The GM service rep told me that a wheel bearing would not cause that problem. My plan is to take it to the GM shop and see what they fine. But if they are going to do the same thing with the scanner codes , I might as well just start replacing parts and save the labor. This is a 2007 GMC  with 50K Miles.

 

[Hanr3]

ABS sensors are fairly simple to replace. They can be inexpensive if the sensor can be removed without replacing the unit bearing assembly. Some bearing assemblies are just that, an assemble and to replace the sensor the whole thing is replaced. Could be a defective sensor was installed, new parts have defects too. Rare, but it does happen.

Next up the chain is electrical connections. Could be an intermittent connection due to dirt or debris, or a loose wire in the harness. Also happens, especially on a truck that old. Mileage has little to do with it. Next level up is the ABS computer, they do fail as well.

A good technician with dealer instrumentation can find the problem wihtout being a parts replacer. That's why you pay the big bucks at the dealership. However, the test results are only as good as the equipment used to do the testing. There is nothing that says this is your exact problem. All comes down to interpretation of the test data. This is where a good technician becomes invaluable. The dealer doesn't want you returning, makes them look bad and your not satisfied with their service. However, when you take it to someone else, the dealer now has a tougher job trying to figure out hat the other guy "fixed". Best to return to the first guy until its fixed right.

When was the last time the rotors where replaced?
Is this truck 4x4?
Do all 4 tires match (same brand, make, and model), have they been rotated, and are they are the proper psi?

Why do I ask these questions?
ABS system detects wheel speed diferences, according to teh system the RT Front is different then the rest.
Rotors- rust flakes have a negative effect on ABS sensors, especailly if they get jamed in/around the sensor areas.
4x4 systems can cause the ABS system to trigger codes if engaged on dry pavement, this includes All-Wheel Drive systems too.
One tire of a different size can also trigger ABS codes. Just because the tire is the same size per the tire rating system, does not mean all tires measure the same size. Tires wear unevenly, thus why we rotate.

Each tire manufactures tires will differ in size from another manufactures tires of the same size. To keep this simple, assume you have 31" tires. Brand X 31" tires could actually be 30.5", brand Y could be 30.75" and brand z could actually be 31.25". None of them are the same size, yet they are all 31" tires. This difference will screw with the ABS system.

Did you install larger size tires than was factory original? This will also screw with the ABS system, and it will affect your speedometer unless you made changes to the engine/tranny computer. However the ABS system is controlled by a different competer.


So, while the test data says the RT Front sensor is the problem. Is it really the sensor or is it something else? The sensor only counts and conveys that data to the computer. There are a variety of tests you can do to determine why the sensor is "faulty"? However, I doubt its the sensor, it was repalced, the real issue hasn't been fixed yet. It could be a defective sensor, but two of them?


Simple things to check first.
tread wear on each tire- is it the same on all four?
Have you checked each tires psi and made them all the same?
Have you rotated the tires to see if the defect moves to another wheel sensor?
Did you upgrade tires?
Are your tires mixed brands, models?
IS your truck in 4 wheel drive? My wife has engaged 4x4 via the push buttom on dry pavement before. Shae calls me while traveling and is 150 miles from home. told me the truck is parked at a mechanics and she had to rent a car because it was making a horrible noise and was hard to steer. 4x4 was engaged, and the drivetrain was bound up tight. All she had to do was drive in gravel, or grass and turn the wheel a time or two after she turned 4x4 off.

Retorical questiosn, you don't need to post up the answers here. But investigate them and figure out where the problem lies. Good luck..

 

[Hanr3]

One other thought.
Do you have a broken belt in the RT front tire?
Is the tire out of balance or does the steering wheel vibrate at speed?

Vibrating steering wheel is generally front tire balance issue.
Vibration in the seat is usually rear tire balance issues.

A broken belt makes a tire run like an egg and may or may not vibrate. It may or may not howl at you. The general sign of a broken belt is a road noise at one particular speed.

Part of a good diagnostic check is a test drive.

Yes, I have turned a wrench or two in my day. Replaced or rebuilt almost everything on my vehicles over the years. About the only thing I haven't rebuilt is the engine. Yep, rebuilt a few transmissions.

Good luck and ask your mechanic some questions. I gave you some ideas on where to look.

 

[72cougarxr7]

It sounds like the work done so far is pretty typical for an abs sensor issue on a GM truck.

I worked at a GM dealer for a few years, sometimes a new sensor wouldnt solve the problem and  the whole wheel bearing assembly had to be changed. The reluctor ring is sealed inside the bearing unit and would sometimes be contaminated with moisture, rust, metal shavings etc. So a new sensor would still not read properly on the old bearing.

If the whole bearing and sensor unit were changed, and the code came back, you likely have either a wiring issue or faulty abs module. Both can be tricky to find and diagnose.

You may have to take it to a dealer or a mechanic with a very high end scan tool to figure out the issue.

 

[eliallen]

The GM mechanic  found the new wheel bearing the bad, with just good troubling shooting and a  jumper wire. Something I recommended to the mechanic that replaced the wheel bearing. I have many years in the auto repair business. If I could not fix a problem for a customer, I would not charge. My age/medical condition prevented me from doing it myself.