Sunday, June 9, 2013

2000 Ram 1500 Shows "NO BUS" Message

Dodge Ram 1500 Will Crank But No Start


If you're seeing a no bus message along with a no start condition then that tells us that the PCM is down. While these problem occurs you'll probably also notice that the fuel gauge and voltmeter don't work when the key is turned on.

There are Few Possibilities To Be Tested And Confirmed:


  • A loss of power or ground will prevent the PCM from waking up. Check fuses in both fuse boxes. If ok then you can unplug the black PCM connector and check for battery voltage on pins 2 and 22 with the key on, and ground on 31 and 32. If these are ok then you can move on.



  • A short to ground on a 5v reference circuit will take the PCM down. This circuit goes to the cam, crank, TPS and MAP sensors. A short to ground on this circuit can be an internally shorted sensor or wiring issue.



  • A short to voltage on the sensor ground circuit will also take the PCM down. This is the black/light blue wire that goes to all sensor on the engine and one in the trans, a short on this circuit can also be a wiring problem or internal sensor issue.


Start with checking the powers and grounds and then if they are ok I would move on to checking the 5v and sensor ground circuits.

This will help.
Thanks.


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