So i am looking for a bit of advice from somebody that knows some stuff.
Van is new to me, previous owner bought it off the showroom floor and kept up on the service through the dealership.
It will start sometimes and runs fine for a random amount of time before shutting off. Sometimes it will restart right away other times i check it a couple times a day and it has taken days before it will start.
When it runs everything is good and i get no codes from PCM on odometer. When it wont run I have no reading for fuel, oil pressure, and voltage. The odometer reads "no bus".
I have gone through the Starting *no response from pcm with a no start condition diagnostic in the "powertrain diagnostic procedures book for the 2002 ram van/wagon book.
pcm fused B+ 12.4v
pcm fused ignition switch 12.4
pcm ground circuits 12.4v (sensor ground also) but on the second connector the speed sensor ground showed not a ground. Tested for ground at speed sensor and it is good. not sure how this sensor works but it shows as not a ground when it runs and the same when it wont run.
TPS 5v supply circuit at TPS harness connector 5.17v
MAP sensor 5v supply circuit at MAP harness connector 5.17v

At this point book says "If communication is available with a PCM on a like vehicle, replace and program powertrain control module in accordance with service information. Perform powertrain verification test ver-1."
Powertrain verification test version says check engine components and oil and then do pcm reprogramming to match vin and mileage, erase codes in abs and air bag modules. If it wont start then the only step left is to check for any related technical service bulletins and/or refer to the appropriate symptom list (diagnostic procedures).

I am unable to find the technical bulletins for this van and am not sure if any would apply to my situation.
As it seems I need a new PCM and if that does not fix the problem the book sends me in a loop of replacing PCM's unless a service bulletin has more diagnostics than what was in the orignal 2002 powertrain diagnostic procedures book.

I cant afford to take this to the dealership, assuming they will follow the same book i have just bought.
Any tech's out there have any advice or is it time to throw a new pcm at this thing?

 

it seems as if there are three of us with similar situations

I have had a similar situation since last Feb... replacing my PCM did not help as I get same symptoms... I have a 2001 I wrote extensively about my troubles in the Feb to May time frame, but with summer heat have all but given up after replacing all sensors, etc.

BELOW see a pic of my PCM part number


personrlr in FL describes a similar no bus condition... he has a 2002 and has several threads currently on this board

I am beginning to think my problem may be the BCM (body control module) an electronic box mounted near the doghouse under the radio... I have not found a replacement part for that.

I live in KY, he lives in FL and with you out west we got the whole US covered...

 

Did see that Cardone offered a repair service on the BCM. Need to mail it in to them. Info was listed on their website.
https://www.cardone.com/

 

thanks a1mfw
best news I have seen in a long time...

 

I am interested to know if you do this, and it works, what the cost is. I cant throw money at this problem, and am unwilling after all the research i have done. i do see in the book there are only 2 wire splices connected to the pcm and both lead to the bcm. I only bring this up cause my brother worked on the line as a tech for many years and told me that splices could cause a wide variety of intermittent problems through the computer system. I havent had a chance to get him to look at my van, and he did not work on dodge. i may be calling him to lend me hand. he has guided me for my whole life when it comes to things about cars and always comes up with a solution. but again he didnt work on dodge nor did he work on these newer computers.

 

I have looked/researched this PCM nobus BCM problem quite a bit. it seems that the whole line of Chrysler mini-vans had quite a few problems with nobus in the late 90's to 2003-4 where the BCM was at fault... but there also seems to be as many different reasons for nobus problems and solutions as there are stars in the sky... no one answer for the nobus problem solves it. Unless you have one of those $3K DRB Chrysler scan tools or want to pay $100+ an hour at the dealer, and pay full retail for parts thrown at the problem... well I can't do that with a 16 year old van.

I just gave my BCM to my friendly local mechanic to run it through his jobber... Cardone will not deal with a customer directly. This mechanic runs a 4 bay family shop in his backyard and is well respected and has all the equipment and knowledge with 40+ years working at GM dealerships between him and his full -time mechanic son who also works there... he has worked on my van, but has not worked on this particular problem as we both realize it is too expensive for him to throw time/labor/parts at it above what I have already done. I today supplied him with the BCM and the vin and mileage and he was told that the BCM would be tested before it would be rebuilt. We talked between $100-$200 should it need rebuilt, which I agreed to. He told me to give him two weeks.

I have finally keyed in on the BCM because the van did have a few strange things happen with the on-board security system just prior to my van crapping out entirely last February... and the BCM controls that system. My FSM also shows the BCM as the source voltage for the OBDII bus (see bus termination pic). I have looked at wiring and cleaned grounds till I am blue in the face (nothing seemed to be bad looking at it with a magnifier even), and nothing else has worked so far. If this does not fix my problem I will be parting out my van this fall.

I have attached pics of the BSM for my '01 2500 van which may be different than your '02

 

RSData: You may want to ask him to open the BCM and visually inspect it. You can do this with the Chevrolet BCMs and then solder over the cracked PCB traces and loose connections on your own.
Steve

 

thx Steve...
I'm an old solder jockey from the early 70's... I looked it over with a high power mag glass... board is covered with a thin film of something that smokes and stinks like crazy when hit with a hot iron... probably needs some type of chemical wash to get it off... board looks great... just like brand new... no visible defects... this is what makes me so mad... every thing I look at looks brand new, with no visible signs of degradation... yet something is intermittant

 

ok so yesterday i went and took a look for my bcm/ctm and my 5.2l 2002 dodge ram 1500 does not have one. I see the connectors plugged in to "caps" that are snapped onto the support where the module should go.

 

There is no ONE particular thing that causes this. It can be ANY module or ANY 5V sensor on the engine or transmission. It can even be an ASD issue on the O2 heater or an O2 sensor itself. I have even seen this caused by a shorted SEATBELT switch VIA the Airbag module.


The problem is the older cars have a SINGLE wire BUS system. This makes it less fault tolerant, BUT easier to diagnose. However, the diag test is subjective to a LIVE 100% condition, which you apparently do not have.


I just fixed an old 2001 B Van this week with a NO BUS. Water had been running all over the ABS module, but through the battery tray, carrying all of the acid residue down with it. Pulled the ABS connector and it came to life. Got the van running finally, then it crapped out again when the bad battery was changed. Disconnected the battery and it came back to life again. Pulled my hair out. Depending on the severity of the BUS failure, it can damage the BUS circuit of more than one module.