Hi, I am new here. I have a 2003 dodge ram 3500 diesel, 5.9 cummins, 24 valve, with a 48 RE transmission. I had the transmission rebuilt last year with a stage 1 rebuild. I had to take it back due to shifting problems and random temp light on the trans, but the temp light does not stay on long. When they looked at it they said that they can't communicate with the TCM. My question is has anyone had/has this problem or possible troubleshooting things to due to figure out why? I think my ignition switch is going bad could that have anything to do with it? Thanks in advance for any advice.

What are the ignition symptoms? My 03 haso some play in the ignition. Have to make sure it is in off position or the blower runs the battery down. Sucks when you are running late in the am.

the key will not go back into the acc. position, and in the off position the blower will run without the key in.

My ignition has Don that for years. I just half pull the key out and turn twards the on position. The Com issue my best guess would be to check every connection our trucks have a habit of plugs coming loose. After that cpu problems suck.

I bought a used 03 ram 3500 5.9l that had the trans replaced. Shortly after buying it, it would stall when turning then starting going into limp mode. I would run a code reader and did the key thing to get codes that way as well. The code from the dash was always the p0700 code. After taking it different shops and getting no more. I swapped the tcm out with the one from my 97 ram 1500. I have a bad tcm. Now I am looking to either my tcm repaired or replaced.