a obd2 plug in tuner isnt going to cause your bus to stop talking. i would not do anything with a tuner till you figure out what happened to your bus. if you have a bus issue... trying to tune your pcm could cause both the pcm and tuner to turn into paperweights. i would go and repair all said bad grounds. there are some in the dashboard too im sure.

 

I added a fat jumper between the ground on the a/c compressor and the ground on the PS bracket w/o effect. Battery was dying really quickly since I rarely drive this truck (partially since it's a hauler, partially since it stalls so much), so went ahead and replaced it (with a Duralast Gold), no effect (but it needed to happen pretty soon anyway, so no regrets).

Although I already replaced it, I'm going back to the PCM as the root cause. My original PCM had an obvious bad solder joint since ASD would trigger but truck would immediately come back to life if I pressed on the PCM connectors-- no "nobus" error on that PCM ironically. The first replacement PCM they sent me was DOA (and they later said my truck had "blown" it), so the one in there is the second replacement. MY first PCM wasn't blown and this one hasn't blown, so I think they were covering their butts blaming my truck.

I sent this second replacement PCM back a few months ago, and they said it tested good and returned it. After all my troubleshooting since then, I'm convinced this is a heat-related issue (because it fails like clockwork-- can go an hour in the evening but only 15-20 minutes at Noon) so, assuming they really did test it, I'm sure it tested fine on the bench....

I'm going to try to get someone on the phone and explain all of this. Hopefully they play ball.... I'm really regretting not just paying the $$$s and getting the replacement PCM from Napa. Word to the wise for anyone coming across this thread later.

All of that said, anyone have ideas on another head-related root cause other than the PCM?

 

Should I replace the pcm? I just dont get why it is saying no bus. I dont want to sound stupid, but what does that even mean? There is nothing wrong with the truck at all. It runs just fine, short and long periods of time

 

No bus means the PCM is not communicating with the Instrument Cluster. The "bus" it is whining about is the communications bus.... which on your truck, includes the central timer module.

Look for posts by CMcKenna, he wrote some good stuff on diagnosing no bus. I miss him.

 

I get more confused the more posts I read. Everybody is having trouble with stalling and the cluster not working. Mine works just fine, doesnt stall. Why would it be popping up still?

 

Did you set it back to stock yet????? And reset the PCM ????

 

i wouldnt set it back to stock till you get whatever it is in the dash to talk right, something isnt connecting right!

 

It can still run fine when you have 'no bus' displayed, mine ran okay when it happened to me. Just like Heyyou said, just means the cluster is not talking to the PCM.

Did you guys ever check the fat plug with a single large screw in the under hood fuse block? Check and clean your ground on the PCM, and all chassis connections? If you don't do the simple stuff first, why bother at all?

 

Folks I had the same problem on a 2002 Ram Van; Starter turned the engine over but would not fire; no bus message and fuel/temp guage on zero.

I went through the archives and did the following:
1 - disconnect both battery terminals; wait 5 mins; reconnect - same problem
2 - check the ASD relay- swapped with another - same problem
3 - removed and checked all fuses - same problem
4 - ran a wire from battery ground to all appropriate grounds - same problem
5 - removed 3 connectors on the PCM; replacedl - same problem
6 - WIGGLED the far right connector on the PCM - hear relays/fuel pump jump into action - guages ok; odo cleared; engine started right up.

Obviously there is a bad connection either in the socket or the PCM - or it was not seated correctly. Sprayed conntact cleaner; smear a bit of di-electric grease in the pins and SNAPPED the connector back.

So far - so good

Gerry

 

Not going to disagree with either one of you, as far as the possibility of it being a bad connection. But the tuner "smartchips" (never heard of it), needs to be removed the equation.