Won't Start - "No buS" Code
 

I have a 2002 Dakota with the 4.7 V8 that would not start today. It would occasionally be difficult to start and recently would sometimes stall. Today when I went to start it would just crank, never even a hint of firing.

The only code it throws is "No buS". Does it sound like the PCM is shot? The fuses all look good. It has about 155k on it. I got laid off a month ago so I don't want to just throw parts at it.

Thanks,
Doug

A bad PCM is possible but something could be shorting out the computer bus too.

Were you getting any codes earlier?

Nope, no codes, even when it stalled it didn't throw a code.

Have you tried a code reader? Without a way to access the bus we're only guessing.

It could be a bad crank/cam sensor.

My OBD II coder reader isn't reading any codes. Only the No buS on the dash.

OK, lets check out the cluster.

Key off. Press and hold the trip reset button. While holding, turn the key on - keep holding it in for about 10 seconds until CHEC appears in the odometer.

I got a 920, 921 and 999. Where can I find what theses codes mean?

From the factory manual -

920 - The instrument cluster is not receiving a vehicle speed message from the PCM.
1. Check the PCM software level and reflash if required.
2. Use a DRBIII scan tool to verify that the vehicle speed message is being sent by the PCM.
921 - The instrument cluster is not receiving a distance pulse message from the PCM.
1. Check the PCM software level and reflash if required.
2. Use a DRBIII scan tool to verify that the distance pulse message is being sent by the PCM.
999 - An error has been discovered.

Disconnect the battery for a few minutes. Remove and clean the connectors to the PCM, look for oil in them.

Disconnected the battery, connectors to the PCM are all dry and corrosion free. Turned the key on with the battery disconnected and turned it back off. Hooked the battery back up. Still won't start, same "No buS" code, and cluster codes are the same. I noticed too that the gas gauge doesn't seem to move when the key is on too.

Thanks for your help with this Dan.

i get no bus when programming with my superchips when it pulls the software out of the pcm. maybe the pcm has no software and needs a reflash