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Rear Antilock Light Sensor???

CraigK

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My "Rear Antilock" warning light is beginning to come on. From old posts I've determined this means the rear shoes are probably worn and in need of replacement.

There is nothing that looks like a sensor of any kind near my rear brake assemblies. (1987 Bronco II, drum brakes, no antilock axle, no antilock brakes)

My question is: what the heck is the sensor for this warning light actually measuring? And where?

CraigRK
 


pangborn83

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only sensor I know of for the rear antilock brakes is the one on the rear differential on the top. Only electrical plug on there.
 

Sasquatch_Ryda

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The RABS light has nothing to do with the brakes themselves, or the brake shoes being worn out. There I didn't think an 87 would have RABS, but if it does there will be a sensor on the top of the differential that will read a signal from the tone ring on the carrier itself.
 

AllanD

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RABS was standard equipment on Bronco2's in 1987.

It didn't appear on Rangers until 1988
and wasn't on all rangers until 1989 or 1990.
(most 2.0 2wds didn't have it)

The sensor reads off of a "tone ring" that is mounted to the ring gear carrier.

USUALLY if the light is comming on metal chips that are a normal fact of life in a rear axle are bridging the magnetic pickup on the axle sensor.

AD
 

CraigK

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Thanks for the info. There is an electrical wire to a sensor-like thing(???) on the top/front of the differential. The trouble light says "Rear Antilock" even though I do not have an antilock carrier?

I'm guessing it would be a good time to pick up a gasket and some fluid and remove the cover, drain, inspect and replace the old fluid with fresh? What exactly might I look for when the cover is off?

CraigRK
P.S. I have an antilock carrier I will eventually put in, I just won't have the time until next summer.
 

Wicked_Sludge

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the only thing that makes the carrier "antilock" is the toner ring beside the ring gear. this is where the "sensor thing" picks its signal up. unless you swapped in the carrier from and even older rig, your carrier has a toner ring on it.

like allan said, the usual cause of a rear abs light is the "teeth" on the toner ring picking up small chunks of metal, thus instead of seeing a steady "1010101010101010" signal as the carrier goes round, the sensor sees "1010110101101101" or what have you.

another possible cause of the fault can be the magnetic tip of the sensor getting too many metal shavings stuck to it, gumming up the reading.
 

pimtool

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I made my light go out by cleaning and sealing the sensor plug in.
 

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Yep, pull the sensor, clean it, put it back in...

No taking the diff apart, or removing the rear cover.

Climb under the truck and look on top of the rear differential, you will see it.
 

surffishin07

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for some reason when my oil light comes on so does my abs. when i fix the oil situation both lights go off(i have a decent oil leak so i lose a quart about every 2-3 weeks.) dont know if this helps at all but just a little to ad
 

Jon Boy

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that kind of sounds like 2 wire shorting on eachother to me
 

CraigK

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I have a slow oil leak of engine also, and usually top it up as the level reaches the lower end of the hatched mark on the dipstick. My oil light has not come on. I added a quart of oil to the engine three days ago, and the "Rear Antilock" light has not been seen since.
Go figgur.

CraigK
 

PANTERA

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My 92 has a rear antilock light on also along with some braking problems. When I come to a stop the pedal has the normal pressure feel, but the truck seems like it takes extra effort to stop until it nearly comes to a stop and then the rear brakes lock up. What should I check for? thanks.
 

frankgeno

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QUESTION> I see this thread is years old. Today is 24 Oct 2022. I have a 1992 Ford Ranger 4WD automatic transmission. Been running great. No trouble lights ever. Today I got stuck in the snow and had to go forward/backward/forward/backward a few times in 4WD in order to get out of the stuck place. When I did the red brake light was on and the yellow Antirearlock light was on. I read through this thread and took the differential sensor out, cleaned it however it was not dirty IMO, and reinstalled it. I also disconnected the battery for 3 minutes and the 2 lights are still on. The truck seems to run fine with the lights on. The oil level in the engine is normal, BTW. does anyone have any ideas how to clear these two lights? thanks
 

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QUESTION> I see this thread is years old. Today is 24 Oct 2022. I have a 1992 Ford Ranger 4WD automatic transmission. Been running great. No trouble lights ever. Today I got stuck in the snow and had to go forward/backward/forward/backward a few times in 4WD in order to get out of the stuck place. When I did the red brake light was on and the yellow Antirearlock light was on. I read through this thread and took the differential sensor out, cleaned it however it was not dirty IMO, and reinstalled it. I also disconnected the battery for 3 minutes and the 2 lights are still on. The truck seems to run fine with the lights on. The oil level in the engine is normal, BTW. does anyone have any ideas how to clear these two lights? thanks
The only oil level associated with brakes is the brake fluid level sensor on your brake master cylinder. That will give you a brake trouble light if the fluid level is low.
If I remember after dinner tonight, I’ll get out my EVTM and see what all is in the circuits for those lights. There isn’t much. The differential speed sensor, the fluid level low, there is an electrically operated antilock brake valve on the driver side frame rail, the parking brake lever activated the brake light. Not sure what else. You could have gotten something packed with snow or frozen in such a way that it’s giving these symptoms, or maybe a stick or something ripped a wire loose somewhere.
 

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I just took a quick glance at the diagrams while I'mcooking dinner. The first thing I see is that low brake fluid level will turn on both of those warning lights at the same time. I'll study it some more. But check your fluid level.
 

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