Checking ABS light w/o scan tool

[mikeso_81]

Hi,

My abs and trac light came on once again and I was wondering if there is a way to check to see which speed sensor went bad without buying a abs scan tool (This is the 4th time this issue has occured.)

2001 Pontiac Grand Prix GT 3.8L

Thx

[Stealthee]

No need to buy one. I stopped at Advance Auto today to have a code read since my CEL came on. The guy handed me the reader and I performed the scan myself. Not only did I find out what the DTC was, but it told me which ABS sensor has been messing up, even though I already had an idea of which one it was.

Cost me nothing but time.

[olopezm]

You can also lift the car and wiggle each wheel holding it at the 6 and 12 o'clock positions. Move it back and forth, if any of them presents any movement you have found the culprit.

Oscar.

[Stealthee]

Only thing is ABS light isnt necessarily from a bad bearing. If the wiring has a short it can cause the light as well.

[Tech II]

I agree with Stealthee....a bad bearing may not cause an ABS problem.....will cause a bearing noise, but no secessarily an ABS problem....

[gmtech1]

Find out what code. If its a front speed sensor code thats resetting, it may not be a sensor at all. This body style, along with a few others, are bad about breaking speed sensor harnesses. They usually break between the connector at the sensor and the first retainer at the lower control arm. It won't always break the insulation, just the wire strands inside the insulation. Good luck!

[olopezm]

Originally Posted by Stealthee

No need to buy one. I stopped at Advance Auto today to have a code read since my CEL came on. The guy handed me the reader and I performed the scan myself. Not only did I find out what the DTC was, but it told me which ABS sensor has been messing up, even though I already had an idea of which one it was.

Cost me nothing but time.

Originally Posted by Tech II

I agree with Stealthee....a bad bearing may not cause an ABS problem.....will cause a bearing noise, but no secessarily an ABS problem....

I agree with both of you, however he asked a way to test without an abs sensor.

According to that question and after performing the bad bearing test I would also disconnect the sensor at each wheel and measure resistance accross it's terminals if the result is 800-1600 ohms the sensor is OK.

The third step (if resistance is OK) would be to measure AC voltage accross the terminals while spinning the wheel. If voltage is greater than 100 milivolts the sensor is OK.

If all these tests are OK then the next step would be to follow the wiring of each sensor towards the EBCM.

Oscar.

[Stealthee]

You should have clarified. The way you worded it, it seemed as if the only way one would get an ABS light is if they had a bad bearing, and that is not the case.

[BNaylor]

It is a waste of time not using an ABS capable scan tool capable of properly reading and properly translating GM/Bosch ABS system codes/DTCs. Although the hub wheel sensors and wiring are the majority of problems the other could typically be an issue with the EBTCM module which is expensive used or new. Mainly applicable to 1999 and up GPs. The only effective scan tool that I know of is the GM Tech 2 otherwise you are just spinning your wheels. Many of the ABS scan tools, if any, used at auto parts stores and independent auto shops/mechanics do not properly translate the DTC to what the problem actually is.

There is no such thing as an educated guess on these ABS braking systems. Proper diagnosis with the right test equipment is the key to effective repair and being safe again.