C147B but everything works?

[rlmarz]

Evening all. 2012 1500 5.7L.

Was launching and recovering the boat and eventually noticed the Service 4WD light. Went and verified that I could achieve 4LOW and 4LOCK without an issue. Everything working as it should, in fact the light only comes on in 2WD. No abnormal noises and actuator working cleanly.

Pulled code C147B and checked out the connector at the FAD. Wires appear fine and played with the harness while someone watched for the light to extinguish. No joy.

I've seen a few wiring diagrams on here for a 3500 and don't want to assume it's the same. Anyone have the diagrams or TSR guide I can go through? Would hate to replace the actuator off the bat especially considering that everything is functioning normally.

 

[jawzs2]

This should help, the manual is for a 2009, but I use it for my 2010 and my son's 2012 and there are not that many differences. I use the connector site to double check wire colors, circuit and pints.

Service 4WD system

Good morning all. I'm a new member and seem to be having an issue with Service 4WD light with multiple symptoms on my 09. My Service 4wd light comes on, dings, shows 4X4 low and high, ESP lights up. All goes off after a few moments. This has been happening for some time now. This morning i was...

www.ramforum.com

 

[rlmarz]

This is money. I'll get under there this afternoon and see what I can't find out.

The way I'm reading it is G303 is likely the focus; signal wire. The fact that the light goes out in 4WD and everything functions leads me to believe it is likely something within the internal sensing circuit of the FAD, but I'll run through the diagnostic to see what we can gather.

 

[rlmarz]

Ran through the troubleshooting guide and everything checked out. No shorts or open circuits to be found, good continuity between ground pin and vehicle ground, good continuity on the signal circuit between the FAD and the DTCM. Conclusion of that one is replace the DTCM before the actuator...

May look to grab an actuator and 'bench' test it to see what that does for the signal. DTCM is from what I can tell a dealer only item due to programming and not cheap. As much as I despise operating with locked in alarms, if everything is working not sure that it is worth it.

 

[rlmarz]

Took one more stab at troubleshooting guides to include the connector in the wheel well. All checked out.

Pulling from AlfaOBD, only one line item from the DTCM caught my eye:

Front Axle Disconnect Feedback: Engaged / 4WD

This was under the Digital Inputs and remained constant even while everything else shifted with the actuator and T-case. Nothing left to do but try an actuator and hope that the input problem is on the sensing circuit in the FAD instead of the DTCM!

 

[rlmarz]

Plugged the replacement actuator in and code is cleared. That's one way to force me to do diff fluid. Thanks for the help folks; let's close this one out.