2002 ram van 5.2l, van stalls, wont restart "no bus on odometer"
2002 ram van 1500, 5.2 liter 45,000 miles
started having problems a week ago, van would stall and i could restart it right away. Then a couple of times later van would not start just crank over and no bus would show on odometer. Waited a few minutes and try again van would start. When van doesnt start you can not hear any relays clicking to indicate fuel pump is kickin on. I tried swapping asd relay for a/c relay as they are the same and still have problem. On saturday afternoon. I started van numerous times, pulled dogbox off to see back of engine. I hooked up fuel pressure guage and had great fuel pressure. Also had spark. Truck would sit and idle and suddenly stall. Looking at guage there is no drop in fuel pressure. Could not duplicate no start condition. Drove van around and it worked ok. Put it back together after checking for loose wires etc. Sunday morning went to take kids to hockey practice, van started then stalled, would not restart, no bus on dash. This morning before work went to van and it started right up, shut it off and took other car, cant afford to break down and not get it restarted. Any idea's would be greatly appreciated. Also cam sensor was replaced in dist.
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Had this happen this past week, the "no-buss' error. I took the advice here in the forums posted awhile back. ...
- disconnect the battery negative.
- turn the key in the ignition forward to start and leave it there for 10 mins. (This drains the PCM and any of the computer power capacitors. This resets the PCM and the PCM counter of "good starts" Total is 255.
- take the key out.
- reconnect the battery
- start the van
If that didn't work, then turn off the key. Pop off each of the 3 wire-harness connections blow out the connectors with CRC electrical cleaner. Reconnect when they dry and try starting again.
If that still didn't work, back out the PCM mounting screws. clean them up for better grounding. Put them back in and try starting.
If that doesn't work to rid the "no-bus", then it's time for a new PCM.
I did all three at a truck stop when we became stranded. PTL, the PCM came back and for over a week, the van has been running with no issues.
Leaving the key on with the battery disconnected is like turning off your computer at home. It discharges any residual power in the computer which puts it back to the "factory new" condition. These PCM's "learn" as we start and drive our vehicles, they adapt to a certain degree based on ambient weather conditions and our type of driving. They store this information in their RAM circuits like our PC use RAM when we work with them, the PCM keeps it's memory alive even when the key is removed from the ignition. So leaving the key on while the battery is disconnected removes the learned information.
Now that makes me wonder how many PCM's have been replaced and all it happened to be was corroded ground screw connections.
Personally I'm not a big fan of the PCM case to body poor ground theory. The PCM has multiple ground wires going to in within the wiring harness which provides a secure power connection. To me the main purpose of securing the PCM to the body is for heat dissipation. But that's just me, I've been wrong before.