Rear anti-lock and brake light come on.

Both lights are coming on after driving for about 15 minutes. They go off if I go into a store or something then pop back on after another 15 mins. or so. There is no change in the braking system either. I took it to O'riellys and their code reader didn't show anything. It did this a little over a year ago maybe once but then quit up until a couple months ago. I really don't want to take it to a shop and pay out the ass for something that might be a simple fix. What do you think the problem would be?

yo,

Try an ABS self test (the test done @ O' will not work for the ABS system)

RABS II is in 87-92

RABS Self Test & Diagnosis Codes; "...The possible flashout codes are listed and explained in the Flash Codes Chart. Note that Codes 1 and 16 are not used.

Flashout Codes Whenever the yellow REAR ABS light comes on during normal operation, a flashout code may be obtained to aid in problem diagnosis. If the vehicle is shut off before the code is read from a RABS-I module, the code will be lost. In some cases, the code may reappear when the vehicle is restarted. In other cases, the vehicle may have to be driven to reproduce the problem and, if the problem was associated with an intermittent condition, it may be difficult to reproduce. Therefore, whenever possible, it is recommended that the code be read before the vehicle is shut off.

RABS II modules have been designed with Keep Alive Memory to preserve stored codes during key-off, and are to be used to service all prior year RABS I systems, except for 1987 and 1988 Bronco II vehicles. WARNING: PLACE BLOCKS BEHIND THE REAR WHEELS AND IN FRONT OF THE FRONT WHEELS TO PREVENT THE VEHICLE FROM MOVING WHILE THE FLASHOUT CODE IS BEING TAKEN.

NOTE: If the red BRAKE light is also on, due to a grounding of the fluid level circuit (perhaps low brake fluid), no flashout code will be flashed and the REAR ABS light will remain on steadily.

NOTE: If there is more than one system fault only the first recognized flashout code may be obtained. Obtaining the Flashout Code A flashout code may be obtained only when the yellow REAR ABS light is on. No code will be flashed if the system is OK. There are certain faults (those associated with the fluid level switch or loss of power to the module) that will cause the system to be deactivated and the REAR ABS light to be illuminated, but will not provide a diagnostic flashout code.

Before obtaining the flashout code, drive the vehicle to a level area, and place the shift lever in PARK for automatic transmissions and NEUTRAL for manual transmissions.

Notice whether the red BRAKE light is on or not (for future reference) and then apply the parking brake. If a RABS(-1) module is installed, keep the ignition key in the ON position so that the code will not be lost. RABS II modules have been designed with Keep Alive Memory to preserve stored codes during key-off, and are to be used to service all prior year RABS I systems, except for 1987 and 1988 Bronco II vehicles. WARNING: PLACE BLOCKS BEHIND THE REAR WHEELS AND IN FRONT OF THE FRONT WHEELS TO PREVENT THE VEHICLE FROM MOVING WHILE THE FLASHOUT CODE IS BEING TAKEN.

To obtain the flashout code, locate the RABS diagnostic connector (with the Bk/Or wire), and attach a jumper wire to it. Momentarily ground it to the chassis. When the ground is made and then broken, the REAR ABS light should begin to flash. NOTE: If the red BRAKE light was on (as noticed before the parking brake was applied), the problem may be with the low fluid level circuit and, in this case, no flashout code will be flashed and the light will remain on steadily. The code consists of a number of short flashes and ends with a long flash. Count the short flashes and include the following long flash in the count to obtain the code number. For example, three short flashes followed by one long flash indicates Flashout Code Four. The code will continue to repeat itself until the key is turned off. It is recommended that the code be verified by reading it several times. In addition, the first code flashed may be too short because it may have been started in the middle. It should be ignored..."

Source: by Steve83 (Steve, That dirty old truck) at http://www.supermotors.net/vehicles/registry/media/280857



RABS Self Test Diagnostic Connector Location pic in an 88; "...it is next to the brake pedal which this is a picture of and is C111; It has the one wire that is black/orange.."

Source: by Jem270 @ http://www.supermotors.net/getfile/552076/fullsize/rabs-test-connector-for-1988.jpg

RABS Codes 2, 4, 5 & 9 (incomplete), Pin-Point Tests & Self Test in an 88; click NEXT to View more pages; miesk5 Note; for all Resistance tests, battery needs to be disconnected; remove Negative cable at battery

Source: by Jem270 at http://www.supermotors.net/registry/media/559308_1

I have some Code pin-point tests in my site @ http://www.broncolinks.com/index.php?index=240

such as:

RABS Code 7 Pin-Point Tests in an 87 Source: by Chilton via miesk5 at Ford Bronco Zone Forums

If code found isn't there, then post it here.

I checked it out and it's code 4 but is that only because my brake light is on? Code 4 also says "RABS valve switch closed". Anyway I have no idea what i'm doing so I guess i'll take it to a shop and get bent over a barrel... I do honestly appreciate you trying to help me miesk5. You helped me get my 4x4 working a while back as well.

yo,

Do the Code 4 test in the LINK I gave above;

RABS Codes 2, 4, 5 & 9 (incomplete), Pin-Point Tests & Self Test in an 88; click NEXT to View more pages; miesk5 Note; for all Resistance tests, battery needs to be disconnected; remove Negative cable at battery

Source: by Jem270 at

RABS Module Location pics in a 90; "...The 90 module is under the dash near the center, on the driver's side. Sort of above the gas pedal & to the right. Gold box with white arrow in this pic. Ignore the Red White & Blue wires, they are for an aftermarket brake controller..."



Source: by ElKabong (Ken, El Kabong) at SuperMotors.net

RABS Component Locations



Code 4 Troubleshooting Pages (1 & 2)