1991 Ford Explorer Sport ABS warning light

Recently the "BRAKE" and the "REAR ABS" warning lights came on and stayed on after brake inspection. Brake shoes are ok. Why is the light still on?

Reply to
shortmom
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The BRAKE light can be turned on simply because the parking brake is not fully released or the switch on it isn't going "off". Perhaps the "inspection" messed up the switch or the guy didn't let the p brake all the way off. I believe low brake fluid will also turn it on. If none of those things is making the BRAKE light come on with the Rear ABS light then note below that there seems to be only one trouble code with should light both lights.

The two most common causes of the Rear ABS light coming on are a bad speed sensor in the differential (near the top with wires going to it, easy to replace yourself, costs about $20) and/or a bad RABS valve. In my experience with two 92's the RABS valve can be bad but not set any codes until you have to hit the brakes hard and make it "work". That seems to make it get stuck or something and then the light comes on and keeps coming back on. The RABS is on the drivers side frame rail, on the inside of the rail near the fuel filter. It's a pain to remove and replace. Price is about $150 for the part.

There is also a diagnostic connector you can use to read the codes from the controller for the ABS system....

There are diagnostics (read: things that could turn on the light) on five system parts: (1)RABS (Rear Anti-lock Brake System) Isolate and Dump Valve, (2) Ring gear speed sensor, (3) Master Cylinder fluid level, (4) Stoplamp switch circuit, and (5) the RABS control module. NOTE: The Explorer/Ranger doesn't have a master cylinder pressure differential switch; only the Aerostar has this.

Try and get the flashout code. For the Ranger/Explorer, this must be obtained when the REAR ABS light is on (unlike the Aerostar, there is no memory). So you need to leave the truck running while you pull the codes. Locate the RABS Diagnostic connector. It is inside the cab, under the dash just above the parking brake pedal where a 53-pin wiring connector goes through the firewall. It is a single orange/black wire with an open connector on the end. Attach a jumper wire to the connector, and momentarily ground it. When the ground is made and broken, the REAR ABS light will give the flashout code. The code consists of a number of short flashes and ends with a long flash. The sum of the short flashes and the long flash is the code. The code will repeat until the key is turned off.

RABS Flashout Codes

1 (should not occur) 2 Open Isolate circuit (In RABS Isolate/Dump valve) 3 Open dump circuit 4(w/ Red Brake Warn Light) RABS valve switch closed or open Dump Valve 5 Rear brake (mechanical) problems or missing signal from 4X4 switch 6 Erratic or low ring gear speed sensor output 7 No Isolate Valve self-test 8 No Dump Valve self-test 9 Speed sensor resistance high 10 Speed sensor resistance low 11 Defective stoplamp switch circuit 12 Low brake fluid 13 RABS control module general failure 14 RABS module program check-sum error 15 RABS memory failure
Reply to
Ashton Crusher

Thanks. My husband says these "tips" will help him figure out the problem. Thanks also for your promptness in responding. You must be a jam-up mechanic!!!

Reply to
shortmom

When you've owned one for 13 years you pick up a lot of info....

Reply to
Ashton Crusher

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