Hello FTE!

I am the proud new owner of a 2013 F-350 6.7L SuperDuty DRW.
It is a Cab and Chassis w/ a CM Flatbed.
I bought it at an auction and from what I can tell it was very well maintained. 1 company owned it and I have service records dating back to it's original dealer.
200,XXX miles, no engine lights on or stored, body is clean/straight, brakes and suspension good, no signs of flood damage, clearly not a badly abused truck.

The only issue is that the seatbelt light, traction control light, ABS light, and parking brake light are all on.
The lights are all on about 95% of the time. I've put about 1,000 miles on the truck now and the lights have all turned off 6 or 7 times, but there is no consistency on when they turn off. but they stay off for a mile or 2 then come right back on.

After doing research on this forum I went ahead and replaced all three speed sensors (2 fronts, 1 rear) and the lights are still on.
I've gone through the connectors at each sensor and hit them with contact cleaner and dielectric grease.
I even cleaned the connector going to the ABS module.

After doing these I unhooked both batteries for an hour and the lights came right back on next start up.

When hooked up to a scanner, it shows codes U0151 "Lost communication with the restraints module" and U0121 "Lost communication with Anti-Lock Braking System Control Module"

I'm at a loss here. I really thought replacing the sensors/cleaning all of the connections would solve this.
Since the lights go off every now and then I have to think it is a lose connector or something but I am not seeing anything.

Has anyone seen anything like this before?
Do I have a bad ABS Module? Is this how an issue like that would show?
Any help appreciated - I am ready for my dash to not look like a Christmas tree all lit up anymore.

Thanks!
-Kevin

ABS Module Connector Cleaned/Dielectric Greases

U0151

U0121

Old speed sensor front left vs. new

 

This isn't a sensor problem (so replacing the sensors won't fix anything).

This is a network communications problem. You're basically driving a computer network on wheels... and your BCM is loosing communications with the ABS and RCM modules. It could be a wiring issue, an incorrectly configured module, a noisy module that's "chattering" (sending excessive messages), or a module that's otherwise failed, either intermittently or with a "hard" failure.

Anything in the service records regarding this issue or any replacements of the BCM, ABS, or RCM modules?

The BCM is the gateway to the HS-CAN network and it communicates with all of the other modules on that network. The ABS module has to receive data from the RCM module as part of its operation. If it doesn't receive data in time, it sets the U0151 DTC. If the BCM doesn't receive data from the ABS module on schedule, it sets the U0121 DTC.

 

Thanks for the response projectSHO89!

Understood on this being a network issue.
I don't see anything in the service history about a failed module etc. It's all regular maintenance items.

I did not realize the ABS Module receives data from the restraints module to function, I wrongly assumed those were 2 distinct systems.

I will focus more efforts on getting to this module (under the front seats) and confirm no wires are frayed and that all connectors are cleaned and firm.

What should my next step be if the RCM appears good? Are there any checks I can do at home to test these modules or at that point am I in the realm of having to go to a Ford dealer?
And what do you make of the lights going off sometimes for a mile or 2? Is the the connection becoming temporarily stable or is that the truck just reminding me there is an issue.

Thanks for your input!!!

-Kevin

 

Go to http://alldatadiy.com and buy a subscription for your truck. There you can look up your codes, get troubleshooting tips, and see all wiring diagrams. It has a good step by step process to find issues. Worth the money every time.