Hi there,

My caravan is up for emission and I've been having the P0601 issue since last December. The van runs great with exception for the last few weeks (see another thread). I had some evap issue before - code P0455 and replaced fuel neck after the smoke test.
Anyway I got a new PCM last week, replaced and on the first start the engine check light went off. Unfortunately on the second start the light came on again and I have no way to reset it. Mo matter how many times I will reset with my scanner it comes and comes on again. The PCM is remanufactured like most of them and the question is - is this a PCM issue or do I have other electrical issue in a van. If so what's causing it and where do I look for it? All electrical issues are pain to diagnose and looking circuit bu circuit can take forever not mentioned the cost at the shop. I appreciate all your suggestions.

Thanks

 

What are the codes you are getting now? And do you still have the old PCM?

 

I cannot communicate with the PCM. Everytime I scan the computer I'm getting 0601. I start the van thelight is off. I turn the van off and start again the light comes with same code again. The van still runs with the same PCM installed. I still have the original PCM in a garage with the same 0601 code. This would be the third PCM replacement in order to push the van through emission. I've been replacing the modules every year since three years. They're usually good for about 3-4 months than thay fail and I keep driving that way until next emission is due.

 

Somewhere out there is a very long detailed forum thread or article talking about troubleshooting a P0601. It's there but I can't find it now. This only shows folks have found something besides the PCM causing a P0601. Check posts #4&5 in this thread.

https://dodgeforum.com/forum/dodge-c...place-pcm.html

 

All you need to do is ask.
Symptom List:
P0600-PCM FAILURE SPI COMMUNICATIONS
P0601-PCM INTERNAL CONTROLLER FAILURE
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P0600-PCM FAILURE SPI
COMMUNICATIONS.
When Monitored and Set Condition:
P0600-PCM FAILURE SPI COMMUNICATIONS
When Monitored: Ignition key on.
Set Condition: Internal Bus communication failure between processors.
P0601-PCM INTERNAL CONTROLLER FAILURE
When Monitored: Ignition key on.
Set Condition: Internal checksum for software failed, does not match calculated value.
POSSIBLE CAUSES
PCM INTERNAL OR SPI
TEST ACTION APPLICABILITY
1 The Powertrain Control Module is reporting internal errors, view repair to continue. All
Repair
Replace and program the Powertrain Control Module in accordance
with the Service Information.

 

OK. Got it. It appears that the cause will most likely be in wiring. Is there any known spot in this "years" that I should be paying extra attention or melted / rusted spots? I still don't get a clear picture what is causing the failure - short circuit, failed another component?
I'm scared to put another one in before I look around and hope I'll find something. Doing circuit test can take forever.
Thanks.

 

Sure wish that was it but no. As I recall it was step by step recollections of a mechanic or engineer, not the FSM narrative. Something besides the PCM was causing it.

 

Well I will say that wiring is one area to look at. Specifics about where to look relative to a P0601? I can only guess and say data bus, grounds, power to and from the PCM. There are wiring problem areas relative to other problems involving the engine management system. Wire harnesses running near the engine exhaust and transmission. Another running under the battery tray. IPM connections and it's internal circuit board. The FCM to IPM connection.

 

I have just repaired a swedish chrysler Voyager with the code P601. I swapped in a used PCM you need the pin code för your car and a DRB3 and select replace PCM in the miscelanious menu under SKIM, follow the steps and 5min later everything is o.k

 

How is the pin code obtained? Also in haynes manual it says obd2 is used for 06 grand caravan. What year was the voyager?