# ABS sensors

**URL:** <https://community.cartalk.com/t/abs-sensors/58488>\
**Category:** Maintenance/Repairs\
**Tags:** sonoma, gmc\
**Created:** [December 9, 2010, 10:32pm UTC](https://community.cartalk.com/t/abs-sensors/58488 "2010-12-09T22:32:50Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Denny239](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Denny239](https://community.cartalk.com/u/Denny239)\
**Post date:** [December 9, 2010, 10:32pm UTC](https://community.cartalk.com/t/abs-sensors/58488/1 "2010-12-09T22:32:50Z")

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Can anyone tell me where my ABS sensors are located on my 2002 Sonoma?

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**Author:** ![tardis](https://avatars.discourse-cdn.com/v4/letter/t/f0a364/32.png) [@tardis](https://community.cartalk.com/u/tardis)\
**Post date:** [December 9, 2010, 10:56pm UTC](https://community.cartalk.com/t/abs-sensors/58488/2 "2010-12-09T22:56:15Z")

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Which ones?  
There’s a wheel speed sensor at each wheel. Usually, there’s a sensor or two at the brake pedal, and there are some hydraulic pressure sensors.

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**Author:** ![Denny239](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Denny239](https://community.cartalk.com/u/Denny239)\
**Post date:** [December 9, 2010, 11:09pm UTC](https://community.cartalk.com/t/abs-sensors/58488/3 "2010-12-09T23:09:43Z")

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I am interested in the wheel speed sensors. My ABS light comes on occasionally and I just wanted to make sure the sensors are not dirty before taking it to the shop.

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**Author:** ![mark9207](https://avatars.discourse-cdn.com/v4/letter/m/71c47a/32.png) [@mark9207](https://community.cartalk.com/u/mark9207)\
**Post date:** [December 9, 2010, 11:15pm UTC](https://community.cartalk.com/t/abs-sensors/58488/4 "2010-12-09T23:15:43Z")

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Your rear sensor is either in the tailshaft of the transmission or in the differential. There is only one for the rear wheels, collectively. Your front ones are at each corner, near the rotor. For 2wd, there is a tone ring on the inside of the rotor the sensors read off of. A damaged, dirty, or misaligned tone ring can cause problems like this. For 4wd, the sensors are integrated into the wheel bearings, which are sealed hubs. There is no cleaning or replacing those speed sensors. Replacing the speed sensor means replacing the hub assembly, and they are a common problem on these 4wd trucks.

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**Author:** ![Denny239](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Denny239](https://community.cartalk.com/u/Denny239)\
**Post date:** [December 9, 2010, 11:22pm UTC](https://community.cartalk.com/t/abs-sensors/58488/5 "2010-12-09T23:22:06Z")

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Thanks Mark. I have a 2WD and I’ll take a look tomorrow.

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**Author:** ![Carveaholic](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@Carveaholic](https://community.cartalk.com/u/Carveaholic)\
**Post date:** [December 10, 2010, 12:51am UTC](https://community.cartalk.com/t/abs-sensors/58488/6 "2010-12-10T00:51:24Z")

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Each front wheel has it’s own wheel speed sensor mounted just on the inside of the rotors. The rear wheels just use the vehicle speed sensor. Lucky you I just happen to have the same truck and spent 4 months sorting out a tricky electrical issue with mine. lemme know if you need anything else. I have the factory service manual handy. 🙂