The subject truck is a 2000 Ford F-150 with 4WD and ABS on all 4 wheels. The truck has about 335,000 miles on it and the ABS module is no. YL34-2C346-AG (made by Kelsey Hayes). The module went bad at the end of 2013 and manifested itself by a continuously running ABS pump. I read here or elsewhere and pulled the 50A cartridge fuse, removed the unit, and sent it to MyAirbags for rebuild. They rebuilt it and returned it, I had it reinstalled and it worked without a light for some time. I am in metro Atlanta, GA and so is MyAirbags, and I chose them for promised quick turnaround (and it was).

Last year I had new tires installed and others rotated, and the ABS light came on when that occurred. I thought that they were related due to temporal proximity, and had the two front sensors tested by DMM and could not locate the problem. I had it in the dealer for trans pan service a couple of months ago and asked them to read the code and advise. They were tight on laborers that day and pushed for time, and I am somewhat concerned about their attention. The response was that they could not read the code and that it might take up to 8 hours to troubleshoot it on another day. I have deferred that and to troubleshoot it myself because we know that a non-communication issue is often a sign of the ABS module and there are some obvious, cheaper fixes than 8 hours at dealer rates (and some less obvious to be explored).

I replaced the rear ABS sensor with a Motorcraft and tried disconnecting the batter and driving at 15 mph for a couple of miles and the code remains on. I had auto parts store guys try to read the codes after that but they could not and threw their hands up. I have not checked the front sensors again since back when. After procured a Micro Pro Grab it set to deal with the stripped T-20 bolt, I removed the ABS module. I opened it along the seam the rebuilder created and visually inspected it. (Photo to follow below). I cannot see any burn signs around the chip/CPU or elsewhere on the PCB.

The truck has fairly new calipers all around, new terminal lines on the front, and very recent ceramic brake pads all around. The MC is at the full level and there has been no obvious problem with the MC or fluid loss.

I have a few questions:

1. How to test an ABS control mod with a digital multi meter (or other instrument) and what parameters? Test for resistance, continuity? What numbers should I see if it is good? (I could not find this info on the web in general or on youtube).

2. There is no obvious damage to the chip or PCB and that is why I want to test. Should I skip trying to test because of difficulty and send it to a rebuilder like MyAirbags again and let them figure it out? Send to a different builder? Trade as a core on one already rebuilt?

3. Cardone seems to be the major rebuilder sold by outlets like Rock, Summit, and others. I could swear that Cardone recently jacked up prices on the units. Is anyone familiar with the quality and have an opinion on whether it is worth it to buy one over a rebuild from a place like MyAirbags?

In the event I need one, I cannot even locate a rebuilt one ready to go from a parts store, a dealer, or from the Ford Parts Catalog online orders. They all need to order them, those available are rebuilt, and are crazy expensive. It appears that the only new ones out there are the occasional new old stock units that turn up from time to time on ebay and other places.

4. Have you had good luck buying used, non rebuilt modules from sources like Automotix?

5. If the control module tests well, what next? I was thinking clean the connections, reinstall, review all steps that can clear a code, and find a shop or dealer to once again try to read the codes if the light is on. Also, pull the wheels again and test the front sensors. Perhaps detach them, clean the connectors, and reconnect. Visually inspect all lines again.

6. Are the Dorman front sensors suitable replacements? (I am talking sensor plus the short cable to the connector). They are about half the price of any Motorcraft or Ford OE sensors I have found listed on the internet. The price difference on the front units is far more than for the rear sensor, which can be obtained at a reasonable price.

 

PCB of ABS control mod. It does not (at least to my eye) have obvious burn marks on or around the chip or bad solder points.

Do you see anything? Ideas?

 

I wouldn't test or replace "stuff" until you get the code(s) read so you have an idea of what to test.

 

The problem, as I stated, is that the dealer could not read a code. No one else can either. That generally indicates the ABS control module is shot (but the module does not have the obvious signs of trouble like blackening around the chip). Therefore, I am reduced to troubleshooting and resolving by a process of elimination.

Oddly, the ABS light is still on even after removal of the 50A cartridge fuse and ABS module.

 

Then there should at the least be some Uxxxx codes present. Resolve that and then you should be able to read the Bxxxx code(s).