Ecm/pcm

Rollin Coal

Rollin Coal

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Are the ECM and PCM linked, or electronically signed together?

the ECM in itself will run the motor, the PCM is there for the vehicle part of it (instrument cluster, obdII port and whatever else)

basically what I'm wanting to know is if you were to wire the ECM correctly to run stand alone, will it run the motor with out the PCM being there?
 
I know both are VIN locked and I've seen issues with people who have put opposing vin numbered ECM/PCM's on their trucks.
 
BgBlDodge said:
I know both are VIN locked and I've seen issues with people who have put opposing vin numbered ECM/PCM's on their trucks.
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yep, ive seen that too, i just wonder if the ECM will flip a **** if theres no communication from the PCM
 
im kind of interested in this also. i was wanting to do a auto to manuel swap in my dads 02 dodge.
 
Rollin Coal said:
yep, ive seen that too, i just wonder if the ECM will flip a **** if theres no communication from the PCM
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Try pulling the CCD bus wires out of the ECM and see if it runs. That should be the only thing that connects them.
 
sweet so you dont have to change any electrical or anything like that? just take the auto out and in with the manuel?
 
Rollin Coal said:
Are the ECM and PCM linked, or electronically signed together?

the ECM in itself will run the motor, the PCM is there for the vehicle part of it (instrument cluster, obdII port and whatever else)

basically what I'm wanting to know is if you were to wire the ECM correctly to run stand alone, will it run the motor with out the PCM being there?
Click to expand...

Well if I get ambitious enough to get my truck running this week as I'm very hopeful for, we'll see if it works. To my knowledge, the ecm runs the engine and only the engine. It will start without the pcm. The pcm controls things such as cruise, and some of the interior accessories. So I don't see why it wouldn't start. I'll be running the pcm from when I had the auto and running the ecm along with the engine out of a replacement 01 that came with a manual.

And if worse comes to worse, I'll just find the wires--I believe around 4 or so, that I could tap into from the ecm and get it to start that way.
 
miles, i know that you are going to have issues doing that, do you have your old ecm?
 
Rollin Coal said:
miles, i know that you are going to have issues doing that, do you have your old ecm?
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Yup I sure do. I lucked out when I bought this engine because it came with it's own wiring harness and ecm. Identical in the aspect that it's the same as far as using the cam sensor only. So if and when I have issues such as you say I will, it will be an easy swap out. What issues will I face?:Cheer:
 
You might get some sort of fault code for VINs not matching up and maybe odometer readings, but the engine should run just fine.
 
the engine will start with a different VIN ECM. but, like stated above, none of the gauges will work.. i had to do this once to get my truck home, granted it didnt run very well at all, but it would start and move under its own power. mines a manual transmission tho..
 
Are you going to be using an ECM from a manual trans on a truck with an auto trans? There are different low speed governor calibrations between the two and it might die or lope REAL bad when you put it in gear if that's what you are doing.
 
blu_by_u said:
Are you going to be using an ECM from a manual trans on a truck with an auto trans? There are different low speed governor calibrations between the two and it might die or lope REAL bad when you put it in gear if that's what you are doing.
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Well it's like this. My truck is an 01 that had the automatic. Then I swapped to a 5spd manual but kept the ecm/pcm from the auto. All I did there was ground the neutral/safety wire. Now I'm swapping in a replacement engine. It came out of an 01 with less miles than my old engine. Only difference is that it came out of a manual transmission dodge. So really if the vin lock holds true, then that should be the only problem, if any. I'm definitely gonna report my findings when I do start this beast up.:rockwoot:
 
You should be in good shape then. IF you have any fault codes, you'll most likely never know it. They'll just be there but I doubt the "check engine" light comes on for that.

Where are you located? Anywhere close to western NY?
 
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