My buddy has a Ram with the V6 and he is having problems that I can figure out and here is what I noticed.
if it is really cold it won't idle. You have to press the gas pedal to the floor for it to start, then hold it at 2000 rpm or above for a few minutes for it to idle. Sometimes it will idle and die when you put it into any gear someone's it won't. What I did notice at first is the cluster died and said no bus but idled, then it started dying when it said no bus. But would fire right back up.

I asked if he replaced anything and he said no. I scanned the check engine light and got a evap leak code. He did have a mechanic put in a fuel pump and now the fuel gauge doesn't work at all.

 

What do intake air and coolant temp sensor read when it's really cold ? Are they ballpark correct ? The sensors share a sensor ground at the PCM with the fuel level sensor so I wonder if the "mechanic" eff'ed something up that biases the readings.

 

They seemed to be pretty accurate in the day it wouldn't idle. When I went to look at it with more tools, it fired right up and it didn't do the no bus

 

How's the throttle body look? Wonder if it is too restricted from junk to pass enough air to idle the engine when it's really cold.

 

I cleaned it less than 5000 miles ago. It really has me stumped. I was thinking crank sensor but I don't know. He lost his job to COVID so he can't just throw parts at it. I also thought the IAC since it wouldn't idle

 

Check TPS values, and temps, as well.

 

Temps checked out good and the tps was 11% at idle

 

Hhhmmmm.... I would be tempted to take the coolant temp sensor out, throw it in the freezer for a bit, plug it back into the truck, and see what the PCM thinks then. Wonder if it just fails below a specific temp.... Having to hold the gas to the floor, and idle high till it warms a bit would indicate a temp sensor problem.....

 

That's where I thought. But they didn't explain the no bus. They sensor isn't on the 5v

 

Um, yes it is.......