The ABS and brake light on my 1998 VW Passat go on after approximately 30 minutes of driving. The VW dealer wants to replace the ABS module and L/R sensor. My local mechanic finds no problem when he scans the module, but it is before the light goes on.
Can you advise?
When the light comes on, the computer stores a code. So your local mechanic should look up the code "History" and he should see it. (Provided he has a scanner capable of reading the codes.)
Do beware of dealers. Get a second openion. A wheel speed sensor will cause a code, as will other issues.
November, 26, 2010 AT 11:50 PM
Thank you E.C.
My mechanic said he can detect no memory of a code with his scanner.
November, 26, 2010 AT 11:59 PM
No problem, glad I can help.
As for your issue, all scanners aren't created equal, especially when it comes to foreign cars. A scanner must have the capability to read ABS codes and have the necessary software for the make and model.
If your ABS light comes on, there is most certainly a code present, or at least a history of a code. The purpose of the light is to inform the driver that the computer detects a problem and it always stores information for that problem.
If the issue goes away and isn't detected by the computer for a certain amount of drive cycles, it will erase the code.
Also, if your mechanic has the capable scanner and the know how to use it, he can perform a "Drive test" with his scanner to reproduce the faulty condition as well as monitor all the sensors in real time. He can't miss the fault then.
I suggest you keep looking for a tech who can truly perform a diagnostic check before you spend a LOT of money replacing the ABS module.
November, 27, 2010 AT 12:10 AM
Sounds like a good plan.
November, 27, 2010 AT 12:23 AM
Also, if you do get a code, or you suspect you're getting some erroneous advise, don't hesitate to ask. Besides helping people with specific repair procedures and diagnostics, we also arm our forum members with unbiased advise for dealing with dealers and local shops.