I have a 95 F250 psd. I was backing up out of a driveway and backed to far into a ditch with the rear wheels. I did not go in square however as the right rear was extended down into the ditch and the left rear was "squished" up into the left fender well. Ever since then, the abs/brake light has been on. I feel no difference in the brakes. Where would be a good place to start tracking this down.

Thanks,
Randy

 

Is the speedometer working correctly? There's a sensor (Vehicle Speed Sensor, VSS) located on top of the differential housing, about 2" to the left of center. It's possible that the wire has come loose.

 

The speedo appears to work just fine. I have noticed no difference in how the truck indicates or performs other than the stupid abs/brake light.

 

Ok, is the ABS light flashing?

 

No, it is constant.

 

Does your '95 have both the red brake & yellow ABS lights? Got a manual trans?

 

Yes, it has both lights. It is auto trans, 2 wheel drive.

 

When you start the truck do both lights come on? Do they both stay on, or only the ABS?

 

Both lights come on and stay on.

 

This is from the '96 Ford service manual...

Warning Lamp Indicators

The red BRAKE warning light is constantly monitored by the anti-lock electronic control module. If the red light illuminates, the anti-lock electronic control module will disable the RABS II system and turn on the yellow RABS light. For this reason, diagnosing and resolving any base brake concerns illuminating the red BRAKE warning light will, in most cases, resolve a perceived RABS II concern.


Brake Light Self Check

The red BRAKE warning light is used to indicate a low fluid level condition or parking brake applied condition. To check this light, insert the key in the ignition switch (11572) and turn it to the START position. The light should glow in this position. If it fails to glow, go to the Symptom Chart.

Allow the key to spring back from the START position to the RUN position. At this time the BRAKE warning light should turn off. If it does not turn off, recheck the parking brake to make sure that it is fully disengaged. In the event that the BRAKE warning light remains on, go to the Symptom Chart.


Rear Anti-Lock Warning Light

The yellow REAR ABS warning light is used to indicate a malfunction and a deactivation of the RABS II system. To check this light, first follow the procedure above for Red Brake Warning Light Self-Check, and allow the key to spring back from START position to the RUN position. The yellow REAR ABS warning light should perform a self-check by glowing for approximately two seconds and then turning off. If it turns back on and does not flash, then a system concern has been detected. Refer to On-Board Diagnostics, Diagnostic Trouble Codes, Retrieving. If it fails to glow, go to the Symptom Chart.


On-Board Diagnostics


Diagnostic Trouble Codes, Retrieving

CAUTION:
Care must be taken to connect only the black/orange stripe wire to ground. Connecting the red mating connector wire to ground will result in a blown fuse.

Verify the key is in the RUN position (engine does not need to be running). Next, locate the black RABS II diagnostic connector. The diagnostic connector has two mating halves (one of which has a black/orange wire connected to it). Disconnect the two halves.

Attach one end of a jumper wire to the black with orange stripe wire side of the diagnostic connector. Momentarily ground the other end of the jumper wire by connecting it to a good chassis ground for 1-2 seconds. Grounding this wire should start the yellow REAR ABS warning light flashing. If grounding this wire does not start the yellow REAR ABS warning light flashing, go to the Symptom Chart.

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 diagnostic trouble Code 4. 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. This code will be used later for system repair instructions. It should be written down for future use. Diagnostic trouble code 16 indicates that the anti-lock electronic control module detects normal system operation.


Diagnostic Trouble Codes, Erasing

The last step of the System Pre-Check always includes clearing the Keep-Alive Memory (KAM). To do this, simply turn off the ignition while the diagnostic connector halves are separated as described in the procedures for obtaining the diagnostic trouble code above, after which the diagnostic connector should be reassembled to provide KAM power to the anti-lock electronic control module. If at this time a valid code has been obtained, go to the appropriate pinpoint test for that code.

 

my abs light came on before and it was a trailer brake fuse i think. the light would flash if i remeber correctly.

 

O.K. I will perform the test you listed and report results.

Thanks for your time

 

Last time mine came on, I was pulling a trailer thru WI. I hit the brakes and the 4-ways at the same time. ABS started flashing & I couldn't shift the trans out of park. That turned out to be fuse #13. This problem is different. Randy, if you can get the ABS flash code, I can check the diagnostic list.

 

I finally found the wire, performed test as listed above and get 3 short blinks and a long blink. According to the proceedure above, that is a "4" code.

 

Here's what the '96 manual says...

Description

Code 4 is generated when the anti-lock electronic control module detects a short circuit (less than 10k ohms) in Circuit 535 (LB/R). This can indicate a short in the valve reset switch circuit, or a hydraulic leak into dump section of the RABS valve.

Possible Contributing Base Brake Component/Vehicle Wiring Concerns

l Terminal backout in the anti-lock electronic control module harness connector at Pin 6
l Terminal backout in the RABS valve harness connector at Pins 4 or 3
l Bulkhead connector (between engine compartment and instrument panel) terminal backout or loose connection
l Anti-lock electronic control module or RABS valve connectors not fully mated with component
l Intermittent open or open circuit in Circuits 535 (LB/R), or 274 (BK/W)
[535 goes from pin 6 of the module to pin 4 of the connector then to the valve reset switch, 274 goes from ground to pin 3 of the connector then to the two valves in the RABS valve assembly]
l Intermittent short or short circuit in Circuit 535 (LB/R)
l Defective RABS valve
l Worn or damaged anti-lock electronic control module

It then proceeds to offer diagnotics for each of the possible conditions.