Rear antilock light
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From: Cedar Lake, IN
Rear antilock light
Yesterday, I noticed my "rear antilock" light was on. I am trying to determine if there is an actual problem or if its just a fluke. I drove it on a 42 mile round trip yesterday and it rode the same as always and I didn't notice any issues. No noises, lack of performance, etc. Has anyone else had this issue before? 1991 F-150 302/E4OD. Unsure of gearing.
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From: Cedar Lake, IN
Some info from Steve83: RABS Codes
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Did you read the information after the Code Chart for how to obtain the Flashout Codes?
To obtain the flashout code, locate the RABS diagnostic connector (with the Bk/Or wire); on '92-96, it's above the right end of the glove box bottom corner, inside the dash; on earlier trucks, it's between the brake & e-brake pedals near the firewall. Separate the R wire's connector half, turn the key to RUN, and attach a jumper wire to Bk/Or. Momentarily ground the Bk/OR jumper to the chassis (the lighter socket shell). When the ground is made and then broken, the REAR ABS light should begin to flash.
To obtain the flashout code, locate the RABS diagnostic connector (with the Bk/Or wire); on '92-96, it's above the right end of the glove box bottom corner, inside the dash; on earlier trucks, it's between the brake & e-brake pedals near the firewall. Separate the R wire's connector half, turn the key to RUN, and attach a jumper wire to Bk/Or. Momentarily ground the Bk/OR jumper to the chassis (the lighter socket shell). When the ground is made and then broken, the REAR ABS light should begin to flash.
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Yesterday, I noticed my "rear antilock" light was on. I am trying to determine if there is an actual problem or if its just a fluke. I drove it on a 42 mile round trip yesterday and it rode the same as always and I didn't notice any issues. No noises, lack of performance, etc. Has anyone else had this issue before? 1991 F-150 302/E4OD. Unsure of gearing.
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Joined: May 2014
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From: Cedar Lake, IN
I have solved the problem. Turned out to be low brake fluid. After filling, the light went off. I am a bit confused as to why low brake fluid would trigger an ABS light and cause unnecessary panic for me.
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If the red Brake light is triggered on, low brake fluid, parking brake applied, etc. then the yellow Rear ABS light is triggered on. You never stated the red Brake lamp was on. With that on the RABS system is disabled which causes the yellow Rear ABS lamp to illuminate too.
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From: Cedar Lake, IN
If the red Brake light is triggered on, low brake fluid, parking brake applied, etc. then the yellow Rear ABS light is triggered on. You never stated the red Brake lamp was on. With that on the RABS system is disabled which causes the yellow Rear ABS lamp to illuminate too.
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By any chance did you notice if the front half or rear half of the master cylinder reservoir was lower than the other? This would indicate which circuit is leaking fluid, rear circuit is the front of the master ( closest to the cab) and the front is the other circuit.
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From: Cedar Lake, IN
Only low brake fluid (and low vacuum on a diesel) will cause the red brake light and RABS light to illuminate. The reason why low brake fluid disables the RABS is because the RABS has an accumulator that can store fluid while the system is trying to modulate the rear brake pressure, if you have low fluid and the RABS were to engage it could cause the master cylinder to suck air in and you loose brakes, not something you want to have happen.
By any chance did you notice if the front half or rear half of the master cylinder reservoir was lower than the other? This would indicate which circuit is leaking fluid, rear circuit is the front of the master ( closest to the cab) and the front is the other circuit.
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