Rear Antilock brakes come on at 38mph?

[1990SilverFordRanger]

I,m not sure what the problem , had everything on the back brakes replaced , but still at 38 mph exactly every my anti lock brakes come on , wont go away till i shut the truck off.

anything helps! thanks

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[James86]

So your light comes on?

 

[YZ250Rider23]

The speed sensor on the top of the rear diff do go bad fairly often. I would consider trying a new one.

 

[James86]

I replaced my rear diff sensor and that fixed the issue on mine too. I think its like a $20 part.

 

[1990SilverFordRanger]

Cool thanks guys!

 

[1990SilverFordRanger]

Its not the speed sensor , i already changed that ? any other ideas?

 

[YZ250Rider23]

Is your ABS malfunction indicator light coming on? (both brake lights should light up when you start the truck. A red brake light and a yellow ABS light)

 

[YZ250Rider23]

So I was just skimming through the ABS trouble codes, and I found this....

Code 11 (stoplight switch circuit)
This condition only occurs when driving about 35MPH. Depress brake pedal and check stoplight operation. If stoplights do not operate, repair stoplight circuit, and retest system. If stoplights operate properly turn ignition off, unplug control module connector. Measure voltage at connector pin no.11 while depressing brake pedal. if voltage is less than 9 volts repair open circuit between stoplight switch and control module. If voltage is 9 volts or more check 4 way flasher and wiring. A problem with 4 way flasher or wiring can cause feedback through stoplight circuit.

So, do you have working brake lights?

 

[1990SilverFordRanger]

ill try it
when i turn the truck over the anti lock break light comes on then goes away instantly, till i hit 38mph .

 

[YZ250Rider23]

But you still haven't said if you have working brake lights or not... could be a bad brake light switch. I still also believe it could be a poor connection to that rear abs sensor, possibly a bad connector.

Well anyway, I am away from my work computer till monday, which is my treasure trove of information, so I don't have much to go on until then. But you'll need to locate the RABS diagnostic connector. Get up under the driver side dash, and all the way to the side, kinda behind the park brake assembly you'll see a big bundle of wire come in through the fire wall. There will be a connector, probably taped to the bundle with a black/orange wire on one side and a red wire on the other side. With the truck on and the ABS light on (since this will ensure the code is in the memory of the computer) you will need to unplug this connector attach a jumper to black/orange side of the connector and ground it momentarily, for 1-2 seconds. This will get the ABS to flash out your trouble code. For example 6 flashes is a code 6, 1 flash pause 2 flashes is a code 12. Get that code, post it up here and I'll tell ya what Ford has to say about it.

 

[1990SilverFordRanger]

yes , all my lights and signals work , just fine