Cold weather start problems - BCM modules?

[WV_trouble]

Purchased a 2011 2500 Ram with 6.7 purchased this summer in Alabama. Runs like a champ and had no problems.


First 40 degree day (and everyone after) when go out to start there are no dash lights, interior lights, etc. Can put the key into ignition and wait for what it would take for glow plug light to turn off (doesn't display) and it will fire up and start. However upon starting, dash lights still do not come on and get a CF error code on trailer tow control, windshield wipers turn on, radio stays dark, and engine RPM will increase. If I press the brakes, the RPM will go back to 'normal' idle. The heater and fan work, so I have been leaving them on and after a while and quite suddenly - everything will work again normal.


I think it is a broken solder connection somewhere, but can anyone point me in right direction? I placed a portable space heater in the cab this morning (35 degrees) after seeing no interior lights again this morning so I knew it would have the same problem again. After a while I went out and the cab was warmed up, so when I opened the door all the interior lights and everything worked normal. I have been recommended to look into a broken solder connection on a Body Control Module (BCM), a whole new wiring harness, and other electrical ideas, but this is hard to chase down as it only happens in the cold and not sure how to isolate the problem. I have replaced some of the switches, looking for a short but that doesn't seem to be the problem.


Since I suspect it is interior somewhere, my next step was going to be taking the hard warmers (instead of the space heater) and put them on the BCM module behind brake controller. Does anyone have any other recommendations for trouble shooting and isolating the issue? Are there multiple BCM that I should look at? Any suggestions would be much appreciated.

 

[rule18]

Welcome to RamForum. I'm sure you'll get some here.

 

[csuder99]

That's a tough one.

For all I know (somebody correct me if I'm wrong) 2009-2012 were similar to the previous generation in that these trucks did not have a dedicated BCM. Instead the functions were split between the "Totally Integrated Power Module" (TIPM) which sits in the fuse box and the instrument cluster (Cab Controller Node - CCN). Notably the interior lights are controlled by the cluster according to the 2009 wiring diagram. The cluster also takes input from the wiper switches and sends commands to the TIPM to turn on the wipers.

I'd look at connections to the cluster if there's anything loose or corroded. Specifically power and ground connections. Also check the fuses M53, M34, M38 in the TIPM just to be sure. Not obviously blown but otherwise iffy.

If not it may be the cluster itself.

 

[nukegm]

post question on turbodieselregister.com

many informative members there. all diesel.

cheers!

 

[62Blazer]

You need to get a good wiring diagram. See what wires/circuits/fuses are supplying power to the interior components (I'm sure there is a common wire or fuse) and start tracing it back to see at what point you lose the power or ground feed (some circuits switch the power on and off, and some switch the ground on and off). If you don't have a wiring diagram and spend some time studying it you will waste a lot of time and are basically shooting in the dark.

You can always start with a visual inspection. Find out which fuses and circuits are feeding the interior and start tracing the wires and connectors back looking for bare or partially broken wires, bad connections, etc...