I have a 96 Grand Caravan that died coming home the other night and has not run since. I tracked it down to no spark. The primary and secondary ohms check out on the coil. I have 11.4V on the B+ terminal to the coil when trying to start the engine. I checked the other 3 pins in the terminal for the ground coming from the PCM and have one that is a constant ground while the other 2 alternate as they should when the engine is cranking. I believe the problem is the PCM.
My questions:
1. has anyone seen the transistor in the PCM for the ground fail shut?
2. Would anything beside a bad PCM cause this. Like a faulty sensor that shorted the PCM and will short the next PCM if not corrected.
3. Would it stop the other 4 cylinders from firing? I have no spark on any cylinder but the ground from the PCM for cylinders 1-2-4-5 seem fine.
4. I hooked a scanner up to it and there are no trouble codes in the PCM. Why is this if the PCM is bad?

thanks,[/align]

 

do you still get the servive engine soon light during a bulb test
key on engine not running ?
when my pcm/ecm went i checked everything from fuel to spark to the ecm
3 days later noticed the light was not coming on during the bulb test
at over $600.00 for the dealer i wanted to be sure
found one at the wreckers had to match the code # on the ecm

 

What error codes did you pull from the MIL ?

 

I do still have the check engine light. Doing a code scan with the light gives me a 12 (battery disconnected in last 50 cycles or something like that). I got this code immediately after the engine failed and I hadn't disconnected the battery in recent memory. I have disconnected the battery since to see if anything would reset. no luck.

Funny thing is handheld scanner gives me no trouble codes.

 

1996 3.8 ES I am experiencing the same problem likely. I was on the highway and the vehicle ignored the accelerator, then recovered. The engine didn't die then, but then 50 km later a similar incident and the engine cut out. All at highway speeds. No spark (test with plug to intake on front three plugs) and had it towed. Shop did the same thing as I did and suggested no spark and would need wiretrace. If that checked out then a new PCM (pricey).
I did my research and after checking the coils and replacing them and still no result, it could be the Crankshaft sensor, or the camshaft sensor, or circuitryof either. Check those. That is what I will do today.
I also had an extra piece of info. After the shop did their test, I went and tried to start it a few days later. It started, but ran poorly, misfiring, and it gave me misfire code p0352, and could have given me more had the the damn battery not be disconnected (Canadian tire is cheap, for a reason).
The crankshaft sensor may check out, but there is a chance that the flexplate it senses could be damaged = nightmare because the tranny would have to be disconnected to gain access to it. I don't know what to do if the sensors do not fix the problem. They are cheap, and I would do myself if not stranded. hard to find a PCM, make sure you get the one that matches your production year for 1996 3.8L. Apparently PCMs for that year only fit that year, and it is either pre or post nov 1995 production date. A yard would have one about 1000km away from the inventory of a connected junkyard.
Please post any progress you make

 

the origional coil pack passed resistance tests, but i changed the coil pack anyway.

You won't get obd codes unless your engine starts, and i think it would correspond to ignition coil c primary secondary circuit malfuntion.

 

The coil pack did check out so I didn't replace it. When cranking the engine I got 11.4 Volts on the B+ lead to the coil. I believe this tells me from the wiring diagrams the crankshaft and camshaft sensors and the ASD relay are all working. If the sensors weren't sending a signal to the ASD I shouldn't have the voltage at the coil.

I had it towed to the dealer today. The dealer told me yesterday that if I replaced the PCM they would have to burn in the VIN # or I might stillhave the check engine light on. The difference between them doing it and me doing came down to about $130 and they give a 12 month warranty.

I'll post what they say.

 

I believe the problem to be exclusively tied to the pcm. Your third coil lead always to ground is an indication, and I have the same problem only with the 2 5 coil (p0352 indicates problem with primary/secondary circuit of ignition coil b). You are no dummy as your initial post asking for the diagram or description of the pcm would be the right step to diy. The dealership will charge a core charge until you give them your old pcm, and that old pcm is destined for a tune up by taking the resin insulation out and replacing the troublesome circuitry on the board. My guess is it is the capacitor or transistor on the board always shorted, and the actual chip itself is ok. Hard to say though. Lemmie know how your van works with a new chip. I just replaced the spark plugs during this downtime. My everything hurts

 

I have been following your other posts. I have been tracing the wiring and have not found a short with related wires yet. Trying to figure out if the wire blue/orange goes straight to the pcm, or if there is a second wire set, asI noticed the same colouring for a wire going to the power distribution centre. A dealer tech told me to look at the wiring harness under the battery as acids could have dripped down there somehow, but there is no evidence of that on my harness. I am being rather thorough with the wiring trace.

 

Just got back from the dealer. I let them take me for $800 to replace the coil and PCM. The coil drivers in the PCMare bad as I've mentioned before. The dealer says a bad coil is what caused it. The dealer says they found codes that definitely point to the coil, I didn't ask what they were because their mechanic has been out sick.

yeorgos, On my wiring diagram I show an or/dk blu wire going from the PCM to the throttle position sensor to the transmission control module. There might also possibly be one going from the PCM to the engine starter motor relay. This one may also be tan.