I have a 2001 Dakota with the 4.7L v8 and 5 speed manual. I have had this problem once before but it ended up clearing up on its own. None of my gages work and every light imaginable is on. I believe it is the BCM and I have ordered one in the off chance that is the problem but I want to ask and get some conformation on this. I'm completely new to electrical problems and try to stick to mechanical so I'm just looking for any help.

 

The "No Bus" message specifically means there is no communication with the ECM. I don't believe the BCM will trigger that message to pop up. Did you already verify the wires and connectors on the ECM and TCM were fine? Often times some water can get into the connector and start corroding. Also with these computers being 20 years old were starting to get into the range of electrolytic capacitors drying up. So it could be the ECM itself.

 

I have checked all wires on corrosion but there did seem to be some stuff leaking out of the BCM hence the reason why I started with that. Pluss it is a part that is plug and play as well as cheaper than the others. How would I check the other two computers for faults?
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You could try hooking a scan tool to it. If it connects and can read off the OBD2 data stream then its probably just a wiring issue. The TCM is the same but you need a dealer level scan tool. Same for the BCM.

 

Thanks for the help. What codes should I look for to track the issue? I have an OBD2 scanner and want to see if anything comes up but I just don't know what to keep my eye out for.

 

There won't be codes if the computer itself is bad. It just won't connect. Your just looking to see if you have any communications. If you do then you know your looking for broken wires/corroded connections. Honestly its very unlikely to connect if the computers are unable to speak to eachother.

 

This can be caused by a short, oftentimes in the TPS or MAP sensor wiring. Give it a good look.

 

So i looked over all of my connections and I didn't see any corrosion. I'm going to hit all of the connectors with some contact cleaner. A weird thing happened though. My truck sat for a week with no-one touching it and the problem "fixed" itself. I believe that this means it is a wiring issue. I have the new BCM and I have yet to install it but the gages and everything works now. Any more input on what could be wrong?

 

Failing sensor, or an intermittent short. Yep, that's gonna be fun to find......

 

I was afraid of that. There really isn't an easy way to find out where the short is is there?