So here's the problem, I go out to my truck (1999 Dodge Ram 1500 4x4) , put the key in and turn it, the dash lights up and I hear the fuel pump cycle. All the truck will do is crank, after cranking for a few seconds, I stop, then the brake light check engine and the ABS lights come on, and most times the "No buS" comes on the odometer. Then I cycle the key a few times, then the truck fires right up. Other times after the truck has recently been running it will start, but wont idle, I have checked fuses but that's as far as I got. Anyone have problems like this?

 

"No Bus" either means two things.
1. PCM is failing
2. You have a wiring issue which is causing you to lose communication with the PCM, which will cause a no start issue.

 

You think the PCM can fail intermittently?

 

It's possible but usually happens after it gets warm "heat soaked" is the technical name

 

 

It could be something in the five-volt circuit failing as well, that will take down the communications bus. So, start by unplugging things on that bus, one at a time. (basically, every sensor.....) Of course, with some of them disconnected, the truck most certainly will NOT start.... Best to try it when the "No Bus" is actually showing up in the dash. Disconnect things until when your turn the key, you DON'T get the no bus. Plug it back in, and see if the problem returns. Will probably take a couple trips around the sensor to find the failing one. If you DON'T find a failing sensor, or, it seems random which sensor is the culprit, then it's likely the PCM that is bad.

 

There could be more than one thing going on here,
I had the crank no start issue, cycle the key a couple of times, then crank and start.
Turned out to be a failing fuel pump.
I realize that this has nothing to do with the "No buS" showing up, but it could be a
contributing factor to your over all problem.

 

A fuel pump would make sense, but I hear it cycle every time I run the key, I can do more digging into it.

 

I looked into some sensors that can be a probable cause, such as the crankshaft position sensor. Have any ideas what other ones could be at fault to start with?

 

So would mine, turned out to be that the fuel pump regulator check valve was failing, not maintaining pressure on the system.