Intermittant ABS light

[Doc Mark]

I have a friend who is computer illitterate
and has aproblem with his ABS system He has an Imperial by Holiday Rambler, 1995 on a Spartan chassis and a Cummins engine.

When the light comes on, he says he can go to the left front wheel ABS sensor and tap it with a hammer and the light goes out. The initial tap feels and sounds "mushy" but when it seats it is a solid ring feel. But after a hard wheel cut it come on again.

Any suggestions? He has had Spartan look at it twice, the local Ford dealer and the Cummins dealer. All with no lasting results. The sensor has been replaced once, 30 months ago. No long term sucess.

[Doc Mark]

I have a friend who is computer illitterate
and has aproblem with his ABS system He has an Imperial by Holiday Rambler, 1995 on a Spartan chassis and a Cummins engine.

When the light comes on, he says he can go to the left front wheel ABS sensor and tap it with a hammer and the light goes out. The initial tap feels and sounds "mushy" but when it seats it is a solid ring feel. But after a hard wheel cut it come on again.

Any suggestions? He has had Spartan look at it twice, the local Ford dealer and the Cummins dealer. All with no lasting results. The sensor has been replaced once, 30 months ago. No long term sucess.

[RV Wizard]

We (dealership) recently had to replace a set of rear sensors on a coach that had them replaced a year before. Don't know why they only lasted a year but if it's bad it's bad.

[chasfm11]

Let me try a shot in the dark here. When the ABS light comes on, it should be setting a error code, even on 1995 chassis. My 1994 Saturn ABS sets codes that can only be read with a special reader (not an OBD-I or II) but those codes should at least provide information about which wheel causes the ABS light to come on. I agree with Mike that replacing the sensor again may not be a bad idea but checking the voltages at the ABS controller may be something else to do. As an old computer guy, I can tell you that input voltages can cause some strange and repetitive symptoms. All you need is a high resistance contact on the input plug to see a voltage drop. Like I said, it is a shot in the dark.

[Gary RVRoamer]

Here's a possibility: wheel speed sensors are electrical devices and are subject to grounding problems. And of course wiring problems too.

But if the device actually moves or seats itself somehow when tapped with a hammer, it could havbe both mechanical and electrical ground problems.

My guess is an ABS fault code will merely indicate a wheel sensor failure on that wheel, though it might show whether it is a short or an open circuit. At least, though, that would confirm or deny the empiracle diagnosis made with the hammer.