I have an intermittent ABS light that comes on for no rhyme or reason. It will illuminate when I am cruising down the road at a steady speed not applying the brakes and when I am sitting at a stop light. Applying the brakes does not cause it to come on. Sometimes I can drive for 150 miles without it illuminating. Other times I will get back in the truck after leaving it running for a short while and it has come on while the truck was stationary with no one in it. There are not any codes being stored. When the light comes on it stays on continuously until I turn the truck off and then restart it.

It just started doing this after I replaced the rear rotors, calipers and pads which all came from NAPA and are Ultra Prem's.

Obviously, I had to pull the rear axles to replace the rotors on the DANA 80. Did I screw something up when I put the axles back in? Where is/are the ABS sensor(s) located for the rear brakes? Does it work off of the rotors, axles or drive shaft or something else that I have not considered?

I do have 4WABS as the front sensors plug into a connector just behind the fender wells under the cab.

The brakes have been bled using the prescribed method from the Excursion forum. I have also bled them again using the gravity method. I am using regular DOT 3. Fluid level is full.

The master cylinder holds pressure and I have a solid pedal all of the time, never spongy, with the exception of on one occasion the pedal actually pushed back against my foot and I had trouble stopping the truck.

I have searched through several hundred threads and have not found an identical problem.

I remember having a similar problem on a 99 Ex but I don't remember what the solution was.

I am at a loss...

Throwing this to you guys. Thank you in advance for any help.

 

The rear sensor for vehicle speed and abs is located on top of the differential. It's not uncommon to have issues with that sensor after a gear oil change. I am not sure why....just seems to happen from time to time. If I remember correctly, when the VSS failed on my truck, the OD light was also flashing...(but I don't remember for certain) Check your electrical connector at the VSS and also inspect the wiring to see if it's compromised at any point. You can also try removing the VSS and cleaning it off....sometimes there will be some particles clinging onto the plastic housing....if so, try cleaning it off and re-install the sensor. Also a possibility the sensor may be at fault..... it's fairly easy to check with a scan tool.

If you have AE, then connect the scan tool and change systems to ABS. Then look at wheel speed for all three sensors (two up front and one in rear). Then drive around until your ABS light comes on again and then see if any of your wheel sensors are off line. The rear sensor is fairly inexpensive. The front sensors are quite expensive if you have a 4x4 so it's sensible to inspect the wiring before replacing parts.

I hope this helps. Good luck!

 

In addition to Shake-N-Bakes post:

Check battery voltage & alternator. When the batts get low on my 2003 F-250 the ABS light on the dash comes on.

 

How did you determine that there are "not any codes being stored?"?

What type of scanner are you using to make this determination? What specific tests or checks have you run on that scan tool?

In my experience, whenever that ABS light comes on, even when only intermittently, a code is set. I've had different codes set when that light came on, that indicated different problems. But in every case on my vehicle, when a signal was sent to that ABS light to illuminate, a signal was also sent to store the fault code, which I retrieved using an ABS enabled chassis module scan tool, not just an OBDII scan tool.

The right scan tool will also enable you to monitor the wheel speed sensors between your left front, right front, and rear wheel speed sensors. When there is a lag or a difference in these wheel speed sensors, an ABS light is usually set, and a code that corresponds with the specific wheel sensor that lagged behind the VSS sensor is stored and retrievable.

 

Thank you for the replies. I still can't send either of you reps Shake-N-Bake or white Buffalo....says I still have to spread them around. WOW!

OK. I will pull the sensor from the rear end either later tonight or early tomorrow, clean it and test it. The O/D light does not flash on this one.

Batts are one month old from Costco. I have 12.6 VDC with everything off, 13.9-14.1 idling/driving regardless of what is turned on. It drops to 11.6 VDC when the Glow Plugs are powered. Alternator is about a year old and has about 60k on it.

I have a friend that has AE and he ran a quick check with it. Initially there were no codes stored even with the ABS light illuminated. We turned the truck off, powered it back on and the light was gone. We then pulled the 5 Amp fuse in the cab. The ABS light came on with the next cycle of the key. The speedometer also stopped functioning with the 5 Amp pulled. We could not get it to duplicate the issue with the 5 Amp pulled and still there were no codes up to this point.

We then replaced the 5 A and the ABS light went out again. We then pulled the 60 Amp fuse under the hood. The ABS light came on, the speedo still worked, and after driving it a short distance we got a P0500 Vehicle Speed Sensor A code. Drove/towed about 450 miles today with the 60 Amp removed with no issues other than the ABS light being illuminated constantly. The truck stopped without issue and quite well.

My friend said it does not make any sense and wondered if there is something wrong with his AE. We did not do the ABS mode test within AE because I had not read the above post by Shake-N-Bake. He has gone out of town for vacation for a couple of weeks and access to AE went with him.

I have access to an Infinity tool if the same can be done with it.

Also, I do get the intermittent PCM/IDM code. Could the PCM (DPC-402) just not be storing the codes all the time?

 

White Buffalo hit the nail right on the head, I work on a fleet of 99-2011 f-250-f-550's and yes when I get a weak battery or a failing alt. I get the ABS light on as well. I use the snap-on solus plus and there is never a code stored for the ABS and can't even clear the none code to turn the light off. the only way I can get the light off is to disconnect the batteries and touch the positive lead to the negative terminal to draw down the caps and other power storing devices. Just letting you know!!

 

Super. I will do that also.

Does the low battery voltage also cause problems stopping...because it happened again today?

 

Just to throw this out there.

I believe I have some electrical/grounding/surging issues, possibly with the aftermarket HID kit the PO installed.

When I turn them on with the car running, they flash bright a moment, then stay on dimmer and quite often my ABS light comes on.

The ABS light goes out as soon as I move a foot or so.

My thought is they are seeing the voltage drop, but then reset themselves as soon as they get new input from the wheel sensors.

Are you having any other strange electrical issues? Anything not working the way it should?

 

Thank you for the reply. No, nothing at all. The ABS light which started the day that I replaced the rotors, calipers and pads is it.

There are no foreign sources for emi/rfi on the truck.