No speedometer and abs light on

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Jun 23, 2007 | 03:11 PM

Kemicalburns

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From: Bend,OR

No speedometer and abs light on

94 full size bronco 5.8/e4od tranny. My speedometer is not working and i have a solid abs light on. I have replaced the sensor on top of rear diff. Ive ran a KOER test and have nothing that mentions anything related. have good battery connection. thoughts guys?? the tranny obviously shifts hard which i have been told is because of this. should the plug going to the sensor on the rear diff have a constant 12v when key is on?

any help fellas
Thanks

Jun 24, 2007 | 07:47 AM

Cuda_jim

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From: MICHIGAN

There is no voltage on the RABS (Rear Antilock BRake Sensor) on top the differential. It generates a pulsing voltage signal that is sent to the ABS control module.

Check the wiring coming from the RABS.

Jun 24, 2007 | 07:06 PM

Kemicalburns

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From: Bend,OR

i have 4wheel abs. so i suspect either the abs modul or the psom under dash

Jun 25, 2007 | 08:24 AM

bocephus_3349

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From: riverton u.s

replace the sensor on the top of the rear pumkin. Mine di the same thing couple months back. Replaced sensor and than it was fixed. BTW 26.99 from most autoparts stores.

Jun 26, 2007 | 08:30 AM

Kemicalburns

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From: Bend,OR

replaced that sensor already and no change. abs light still on and no speedometer. im thinking either the psom is shot or the rear tone ring in the diff is shot? thoughts

Jun 26, 2007 | 09:56 AM

Cuda_jim

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From: MICHIGAN

The wiring on the RABS is not a common problem but it happens. See if the signal is getting to the ABS module. I don't see how a tone ring can be shot unless the rear diff took a dump. I assume you looked at the front wheel sensors & tone rings & wiring

Jun 26, 2007 | 01:45 PM

rclarke

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The reluctor in the rear end often is damaged. The ears on the limited slip clutches break off and circulate with the oil. When a piece goes between the sensor and the reluctor it damages the teeth on the reluctor. If one or two teeth are damaged the signal is disrupted and will not work. The first clue of a damaged reluctor is if the sensor had any physical damage or deep scratches. You can remove the sensor and CAREFULLY feel the teeth on the reluctor with your finger as you turn the rear end very slowly. AGAIN CAREFULLY!!! you could loose the end of your finger.