I am getting a NO BUS code sometimes. My 2002 Dakota 4.7L V8 Crew Cab will start fine sometimes, usually in the cold morning, or evening time.

If I try to start the truck during the day, it is hit or miss if the truck will turn over. If it does start, during the day it will drive fine for a while, then out of no where the truck will die, while driving down the road or stopped at a light. When this happens I get the NO BUS code. After about 5-10 tries to turn the key, (not start), the gauges will engage and then I know I can start the truck. If the gauges do not engage, the truck will crank and crank, but nothing.

Attempts to self-fix: Replaced the TPS, added fuel additive to a full tank of gas. Thinking it could be a fuel issue? But if it was simply a fuel issue the no-starting/gauges not engaging wouldn't matter. So I don't think it's as easy as a fuel issue.

I've done some research that it could be a PCM issue. Those are expensive. I am trying to do the $20-$50 fixes before replacing the PCM.

Any suggestions?

 

You have a sensor that is failing. Trouble is, there are a bunch of sensors that can cause the problem...... Given its intermittent nature, it's gonna be fun to find.

 

Do you have a idea of which sensors it may be? I'm open to seek and find.

 

That's just the problem. It could be ANY of them. Pretty much anything on the 5 volt bus from the PCM. So, all the O2 sensor, cam, crank, coolant temp, tps, etc.

Generally, the way to troubleshoot the issue, is to start disconnecting sensors when the problem presents itself, and the last one you disconnect when the cluster comes back to life is the culprit. I wouldn't bet real heavily on that working for you though, as the condition doesn't last very long...... Something is getting hot, and failing. Let it cool enough, and it starts working again.

Are there any codes set? Any pending?

 

No codes stored. When you turn the key 3 times then it gives you codes stored. There are no codes. If I do not start the truck, but turn the key after a couple minutes the check engine light will flash 12 times.
But so you are saying that probably a sensor is over heating, which is why it will start in the cold. But even if I have not been driving the truck and it is during the day, and I go to leave work, it will not start.

 

Pretty much. The key trick will only show hard faults though. There are also 'pending' codes, that won't show up that way. Have to use a scanner to check for those. Even the cheap scanners available at your local parts store should be able to pull 'em though.

All it takes is one sensor on the 5 volt bus to freak out, and it takes down the entire system. Thus, the 'No Bus' message. (as I do believe the communications bus uses the same power source...... not 100% sure on that though.) If you have a hard condition, no gauges, error in cluster, and the truck won't start, just start unplugging sensors until the gauges start to work. (one at a time.) If you unplug one, and the gauges come back to life, plug it back in, and see if you still have gauges. if you don't, there's your bad sensor. If you do, gonna have to try again next time.