2002 F350 7.3PS

Been having an intermittent brake issue for a few months now starting early spring. Though it was the parking brake dragging. Torn all of that apart and replaced cables, drum/rotors, shoes all in bad shape probably the originals from 2002. So parking brake is fixed now. Problem is I still have this intermittent brake issue get up to about 60mph and the truck will shutter when letting off the throttle. I get home and sure enough the driver side rear caliper pads are smoking. verified both rear calipers and pins are greased and not frozen. Which leads me to the ABS system. The ABS light suddenly started showing always on no blinking. I hook up FORSCAN and see that I have 5 ABS codes and 1 U code.

B2477 module configuration failure
B2477 module configuration failure (yes twice)
C1141 Left Front Tone Ring Missing Tooth Fault
C1142 Right Front Tone Ring Missing Tooth Fault
C1143 Left Rear Tone Ring Missing Tooth Fault
U1262 SCP Data Link Fault

Ok, some thoughts: No way are all 3 tone rings gone/damaged/missing at the same time. Makes me think the ABS module data is getting scrambled especially with the U1262 code, or the ABS module is burnt up. I pulled the ABS module out and see no corrosion or damaged pins on either end of the connector. I traced the wires in the engine bay and see nothing obvious. The ABS module does partially respond to bleed command.

I tried to update some of the IC and ABS data with FORSCAN example (rev/mile) in the IC and (ASBUILT) in the ABS. The scanner says the update was a success but when I open the configuration again the data has reverted to the previous values. Seems not good. Since I cant update either the ABS or IC I think I have a data link issue hence the U1262 code.

My next steps:
-Dig through the FSM schematics for the SCP wires and test for continuity.
-Find the local grounds and test for resistance.
-I've read about IC requiring resoldered joints on this era F350 but cant gather anything more specific.
-Remove the Previous Owners wiring hack jobs.

Thoughts?

 

Alright, been digging on this. I tore into the dash to see if any of these add-ons might be causing problems decided to pull anything I did not like. Turns out there was a bunch of crappy wire connections with wire nuts and some questionable soldering. Pulled 2 aftermarket gauges out and a dead electronic lock controller. And finally I found some possible root causes: a 14ga wire spliced into the ABS main power wire located in the engine bay. Strangely this wire simply goes straight to the in cab fuse box and splices back to the ABS power fuse. So not really a problem but raises questions and introduces 2 more points of corrosion or voltage leaks. Also, the driver battery and tray show battery induced corrosion all over. I think the battery has been off gassing and caused the grounds and possibly that spliced wire to degrade. As a result the ABS module probably has unstable voltage. I have yet to probe anything because I need some longer DMM leads from amazon(the devil).

So after the de-mods, I cleaned the driver side of the engine bay with some Dawn Powerwash (which works amazing for cleaning oil). Then I dug into the FSM wire schematics to learn all about the what and where for the IC SCP bus and the ABS module.

Conclusion so far is PO's wiring was awful and might be the problem. Going to poke around with a DMM to hopefully source a bad ground or power wire to the ABS module; which might be related to my old battery off gassing and corroding the area.

The IC problem is a similar troubleshoot. I've located all of the SCP bus connection points in the truck [IC, PCM, APCM, DLC, PATS] Now I just need to probe the bus lines at the various points and again hopefully find a broken or corroded wire. The ABS module is on a separate BUS called the ISO which also sends data to the DLC. I'm just going verify the DLC ground /power and bus connections all are connected. The ABS and IC codes are likely separate problems entirely.


PICS

Aftermarket stuff removed



If this is you please stop.



something fishy



other end

 

Good news: is all the wiring is good. Tested the ABS power/grounds, ISO bus, DLC, and the SCP bus. All check out. Bad news: I destroyed the ABS connector. I'm going to re-pin a used one in "fun". Also points to a bad ABS module or bad calibration somehow. I got a new OBDLink EX going to trying re-programming the module but... looks like I need to plan to replace it.

The ABS module wires can be tested right at the connector; see pic. Red circle is continuous positive battery, probe each one with the positive battery cable. Green is ground probe each and touch chassis. Yellow is key on positive battery; turn key to run and probe with positive battery. Blue is ISO data bus probe it with pin 7 on the DLC.



The SCP bus has multiple connections all over but I one I care about is the points between the IC, PCM, and DLC. I pulled all the modules on the SCP bus lucky I only have the IC and PCM but its possible to have PATS APCM. Then I tested the SCP+ (TN/OG) and SCP- (PK/LB) lines lucky the colors are consistent throughout. The other wire I tested was the DLC Module programming signal wire Pin 13 (VT) on the DLC. All tested good no wire breaks. At a loss on the U1262 code doesn't throw the MIL so whatever.

 

To follow up I repinned a new connector. Got one of those Clone VCM2 with a cracked IDS and attempted to reprogram the ABS module. Didn't seem to work as the ABS light and the codes would reappear immediately. I got a junkyard module and swapped it in reprogrammed it and the codes all went away. The chinese VCM2 and IDS cracks work but in this case the module was just done. I'm going to see if one of those ABS repair websites can fix it so I have a spare.