Dreaded "no bus"
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Joined: Apr 2010
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From: Clayton MI
They can say pretty much anything they want, and you have no real way to verify if they are telling the truth, or blowing sunshine up your skirt......
Do you just get the no bus error while cruising around? (and does the truck quit at that point), or do you get the error, and it won't start? or do you get the error, and everything else seems just fine?
Do you just get the no bus error while cruising around? (and does the truck quit at that point), or do you get the error, and it won't start? or do you get the error, and everything else seems just fine?
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Amateur
Joined: Oct 2011
Posts: 36
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From: FL
Aaaaaargh, I know.
Sequence is I'm driving around, engine dies and gauges go to zero, and I try to wrestle the car to the best place possible in coasting distance (PS and PB die with the engine which makes turns off major roads entertaining). If I turn the key on, the gas gauge lifts a very small amt (call it 1mm) but no fuel pump noise. Engine will crank, but not start. If I leave key on, I eventually get no bus on odometer. After a random period of time, at key on I'll get a valid fuel level, hear pump run for a few seconds, and I'll know my crank will be successful. After that, I'll get repeated ASDs until I leave it off long enough that everything is totally cool.
Sequence is I'm driving around, engine dies and gauges go to zero, and I try to wrestle the car to the best place possible in coasting distance (PS and PB die with the engine which makes turns off major roads entertaining). If I turn the key on, the gas gauge lifts a very small amt (call it 1mm) but no fuel pump noise. Engine will crank, but not start. If I leave key on, I eventually get no bus on odometer. After a random period of time, at key on I'll get a valid fuel level, hear pump run for a few seconds, and I'll know my crank will be successful. After that, I'll get repeated ASDs until I leave it off long enough that everything is totally cool.
Amateur
Joined: Mar 2010
Posts: 46
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From: New Jersey
It sounds like a loose connection somewhere in the wiring harness or the connector going from the Engine/PCM harness to the PDC.check that out, that particular one is notorious for coming loose and corroding.It's the one on your PDC under the hood with the 10mm hex head bolt in the middle of it.
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Joined: Dec 2012
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My 99 durango did the same thing. It drove me crazy. I didnt drive it for a year while I tried to fix it. Reading these threads every weekend and trying each and every suggestion. It turned out to be a ground wire behind the battery connected to the inside of the fender. I replaced the ground and have never had that dam "no bus" again. The wire looked fine, but I split it open and it was toast inside the casing. Not sure if thats what your problem is, but figured Id mention it. Good luck.
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Joined: Apr 2010
Posts: 87,380
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From: Clayton MI
Just as an experiment....... if you have a warm place to work, that is well ventilated, or, you can route the exhaust out..... grab a heat gun, start the truck, aim heat gun at PCM, and see if the truck dies... (don't bake the PCM though......) If it does.... you just found the problem.
Other things can trigger an ASD event as well though. Cam and Crank sensors, O2 sensors, and a couple others.
Other things can trigger an ASD event as well though. Cam and Crank sensors, O2 sensors, and a couple others.
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Amateur
Joined: Oct 2011
Posts: 36
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From: FL
Right on schedule: six months and I'm baaaa-aaack.
In January, after rereading all of the nobus threads, I tried pulling all the power connections between the battery and PCM (battery, PDC, both ends of the harness that runs between the PDC and PCM) and thoroughly cleaning them (sandpaper and/or electrical cleaner).
At the same time, we were trying out the Progressive Insurance system where you plug a dongle into your ODB2 port, and they give you a discount based on your driving (which, by the way, is RIDICULOUSLY picky about braking). This puts a continuous, small drain on your battery and, since I'd already had concerns with battery drain since the truck is not a daily driver, I got a battery tender. I was very consistent about plugging back in after every trip so the battery was always topped up.
Since these two changes, I had zero ASD events, even in pretty hot (92+) weather and extended drives (including some moderate hauling). Last week, I locked my keys in the truck with the key on accessory. When I was able to get back in, the truck was in ASD. After turning everything off for 10 mins, ASD cleared and I was able to drive for another 10 minutes before I got another ASD. After that, I beelined for home.
A week later, I had done some clearing work and the debris blocked access to my garage, so my truck went a few days off the charger. I made a quick trip to HD at 9pm (so not hot) and on the way back I had two more ASD events.
So, new theory: I think the voltage regulator is flaky, but it's sensitive to voltage instead of heat. It could be a total coincidence, but two ASDs in a week, both after I let the battery run down. I've just about talked myself into going to NAPA tomorrow to order a (hopefully higher quality) remfg PCM. HeyYou called it a year ago-- am I missing anything or should I just plunk down the $400?
Matt
In January, after rereading all of the nobus threads, I tried pulling all the power connections between the battery and PCM (battery, PDC, both ends of the harness that runs between the PDC and PCM) and thoroughly cleaning them (sandpaper and/or electrical cleaner).
At the same time, we were trying out the Progressive Insurance system where you plug a dongle into your ODB2 port, and they give you a discount based on your driving (which, by the way, is RIDICULOUSLY picky about braking). This puts a continuous, small drain on your battery and, since I'd already had concerns with battery drain since the truck is not a daily driver, I got a battery tender. I was very consistent about plugging back in after every trip so the battery was always topped up.
Since these two changes, I had zero ASD events, even in pretty hot (92+) weather and extended drives (including some moderate hauling). Last week, I locked my keys in the truck with the key on accessory. When I was able to get back in, the truck was in ASD. After turning everything off for 10 mins, ASD cleared and I was able to drive for another 10 minutes before I got another ASD. After that, I beelined for home.
A week later, I had done some clearing work and the debris blocked access to my garage, so my truck went a few days off the charger. I made a quick trip to HD at 9pm (so not hot) and on the way back I had two more ASD events.
So, new theory: I think the voltage regulator is flaky, but it's sensitive to voltage instead of heat. It could be a total coincidence, but two ASDs in a week, both after I let the battery run down. I've just about talked myself into going to NAPA tomorrow to order a (hopefully higher quality) remfg PCM. HeyYou called it a year ago-- am I missing anything or should I just plunk down the $400?
Matt
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Joined: Jul 2006
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From: Gainesville, Ga.
jumping in... i'd be tired of working on it by now and i'd replace it. shop around, the napa unit is probably a common Dorman or Cardone brand, and you might find it cheaper at autozone, advance, etc.
another option is to get one from the junkyard for your year model and equipment options. you might save a lot of money, especially at a you-pull-it.
another option is to get one from the junkyard for your year model and equipment options. you might save a lot of money, especially at a you-pull-it.