AFAik, that'll just give you a no start condition, not a NO BUS

 

If it were me, Id double check grounds (maybe add a beafy 2nd ground), check the PCM mount/PINS (maybe clean them with DEOXIT or CRC Contact/Electronic Cleaner), return that PCM if you can and get a CARDONE PCM w/ a decent warranty that i linked in your earlier thread. Then start jiggling wires around sensors, harnesses, etc and see if you can replicate the condition on demand.

 

thanks for all the replies...
I have been monitoring the forum

Don't read any further unless you have an interest in this unusual beast...


A friend drove down on Wed, 800+ miles to tow my camper as I followed in the van
He is a decent mechanic, 20+ years but home trained... We both look at plugs, and grounds, and PCM pins...

Just to show you how erratic this is, we both drove two vehicles about 20 miles to a restaurant, Wed afternoon, no problem... I get into the van as I leave the restaurant with my key in hand as I always do and the security horn starts honking when I open the door, has not done that in a long time... I use the key to shut it off and start the engine... drive all the way back 20 miles with no problem

next day, Thursday, pull out about noon, and I can't get 3 miles with out No Bus, I sit for about 3-4 minutes, NO bus goes away and I drive back to camp

we start jiggling and testing and he does the same thing I did for the previous 3 weeks... we add grounds, we spray with DeOxit as I have already done several times, NOTHING can replicate the problem... we stop after about 4 hours as it starts to rain hard and I am planning on leaving Friday about noon...

rains hard all night Thursday, drizzle all Friday morning, van starts and drives occasionally bucking, or dies while rolling, restart in N and keep going, not a lot, but 3-4 times, for 125 miles, all in the rain... then sun comes out and we hit a patch in AL where there was no rain, dry pavement, and van gets NO BUS about 20 minutes after hitting the dry pavement, no start twice in about 5 miles... after waiting 5-10 min, No Bus goes away and restart and run another couple of miles, then van wildly starts sending speedo needle from 0 to 50, NO BUS appears then disappears while still rolling and engine running, and van continues to run for about a mile or so with NO BUS showing, then engine dies, and we coast into a church parking lot north of Dothan, AL...

we swap the new reman PCM and put old one back in, jiggle wires, repeat... can never get rid of NO Bus after working on it for about an hour... so we push it into a parking spot and write a note to stick into church door asking to please not tow it away as I will retrieve it with a dolly before next Sunday, AP 3...

Just as we close the hood for the last time I notice a 2+ inch long fresh crack (shiny metal) on the top of the alternator housing... but now we are in a rural area, having passed around Dothan's bypass in heavy stop and go traffic, even stop to gas up on the US 231 bypass... so the heck with it... it is getting late 5:30... and we still have 700 miles to go...

I swear I would have seen that alternator housing crack earlier staring me in the face because it is right on top, over the past three weeks if it had been there before... probably original alternator, at least since I got the van with 130K miles, (now 198,000)...

SO the question is, can a really old faulty alternator, somehow be putting so much noise (spikes) into the circuit to mess something up with a sensor or PCM signal??? Up to the end the battery voltage indicator appeared to be showing a charging situation... not discharging...

I have already spent $300 for a Miami FL reman PCM, because it was overnight delivery, although they did not ship it for 4 days, so took 5 days delivered from time I ordered. I am expecting another $100 core charge to be added to my card any day because the 14 days to send my old one back has now come and gone. Both PCM's, old and reman sit in Alabama waiting for me.

I am beginning to suspect a faulty fuel pump, because sometimes engine dies, but starts right up, or if rolling about 45+ MPH, there is a hard bump, but takes right off again and van restarts itself... The fuel pump was replaced last fall, just as preventive maintenance by a respected mechanic, with a quality unit... but I now suspect that those random "bumps" I have been getting since then, while running at speed that I have attributed to a faulty shift, was really a lack of fuel delivery, that pressurized right back up...and kept me running... MAYBE?

As far as grounds... I have an expensive Fluke digital meter and I know how to use it. If I put one lead on the neg terminal, I can touch the engine anywhere, and the frame anywhere and get continuity.

I have taken the relay and fuseable link bus box apart twice (black box next to battery) exposing the underside and everything is shiny bright... sprayed with DeOxit, and re-seated all relays, swapped out relays... there are four of the same ones all in a row.

When I get the van back later in this coming week, one of the first things I will do is drop the tank , inspect the fuel pump wiring. The second thing will be to replace the alternator and add a "beefy" ground from engine to frame to supplement the one that goes from coil mounting bracket to frame. Then see what happens...

I have tried to describe the almost 4 weeks of this distressing problem to the best of my ability.Sorry to be so lengthy and redundant... I have read and re-read any and all posts on this forum having to do with PCM, and NO Bus, no start, although it appears to me there are quite a bit of differences between van generations on the PCM, connectors and relay boxes... MINE is an '01 with three banks of 32 pin connectors on the PCM.

thanks again for all your suggestions... I will look at and try them all, if I have not done so already, but I will probably do it again... What about that alternator crack showing up????

 

sure can...

have you tried the cluster's diagnostic sequence?

Press and hold the odemeter reset button then turn the key to ON..do not start...the cluster will say CHEC then go through its diagnostics...

according to the FSM, you need a DRBIII scan tool to properly diagnose your condition. It may be well worth the $80 at the dealer (or a high end independent shop) to have this done

 

I will say, just because you have a ground, doesn't mean it is a good ground

a faulty fuel pump can cause problems, I had major problems with my van, until I replaced it... I don't trust mechanics to replace anything on my cars....

so you need an alternator? make sure to get the right one for you vehicle, the one that dodge says came with mine, is a HO unit, not the standard ones that auto parts stores typically sell

 

Cross your fingers hopefully your alternator is the problem, not sure I would have the patience you are showing here.

 

An alternator or a fuel pump is not going to give a no bus (as said before). No buss is a communication (or lack off) issue meaning the pcm is not getting vital info/voltage etc. I would agree to put a reader on it and see what happens when the no buss comes up. If the reader goes out also it's probably a voltage issue going to the pcm or a number of other reasons. With the reader you can monitor what the pcm is getting from the sensors also. This will give you more info to track down the problem. If you have a smart phone there are a few plug in blu tooth style monitors you can get also.


https://dodgeforum.com/forum/2nd-gen...-bus-mean.html

 

To be a tad bit more specific, the No Bus only comes up when the digital instrument cluster cannot communicate with the PCM. That means the problem is with the cluster, the PCM, or the wiring in-between. A fuel pump will NEVER cause the No Bus message, nor will a bad alternator. If you want to test the alternator theory then simply disconnect the battery wire from its output, start it, and see if you still get the No Bus message or not.

 

alloro, I thought disconnecting the battery from a running computerized vehicle is not a good thing? as it will cause the alternator to go WTF! and burn stuff trying to compensate. I do know that back in the day, that is how you could test the alternator, but the computer systems are too sensitive from what I understand

 

From what I understand, if an alternator sends more than 16-17v to the PCM, the PCM does an emergency shutdown internally to keep itself from frying. That would explain the NOBUS and this P-code condition...