PCM pinout differences between Auto and Manual

[dartslantsix]

Still grinding away on my Magnum swap (1994 vintage from a Grand Cherokee). Couldn't get it to run using the automatic PCM (running an AX15). I picked up a manual trans PCM from a Ram (PN 56028319).

Does anyone have a pinout for this PCM? I've googled and can't find one. Or, how do the pinouts change? Obviously, the neutral safety pin changes. Does it go away or is it tied into the clutch switch?

If anyone has the diagram, that would be super helpful.

Thanks.

 

[DionR]

Best I can tell from the diagrams I have, the PCM doesn't care about the transmission in regards to the starter circuit. All of them tie into the same pin, and the difference is whether the wiring goes direct to ground (manual) or through a NSS (auto). At least that is how I read them.

I send what I have over via email.

Hope that helps.

 

[ralphie361]

You should be able to ground the nss pin like dionr said, it goes to the clutch switch on a manual. I'm curious why it wouldn't start with the auto PCM. Both of my magnum swaps I ran on auto pcms until I found deals on manual ones. I had a few trans codes, but they always ran and started fine.

 

[dartslantsix]

I believe this is the key. Looks like manual trans just gets grounded out.

You should be able to ground the nss pin like dionr said, it goes to the clutch switch on a manual. I'm curious why it wouldn't start with the auto PCM. Both of my magnum swaps I ran on auto pcms until I found deals on manual ones. I had a few trans codes, but they always ran and started fine.

I have no idea why either. I've had so many people look at it that also can't figure it out. I got a new PCM from a manual trans and I'm going through the wiring as well. About 75% through it.

The one thing I changed in the wiring is the crank sensor plug. The manual trans sensor won't plug into the harness without swapping the ends. The wires on the sensor side aren't colored, so matched them up how it made sense. Could this have fried something in the PCM? I'm considering getting an automatic crank sensor and spacing it out so it works with the flywheel.

 

[magnummopar]

The black with a white stripe gets grounded. Same pin as auto. If its firing and dieing, its probably crank sensor. ou can call the shop tomorrow and I will give you some tips on how to test it. 541-955-0363 9-5 pacific coast time Evan

 

[dartslantsix]

The black with a white stripe gets grounded. Same pin as auto. If its firing and dieing, its probably crank sensor. ou can call the shop tomorrow and I will give you some tips on how to test it. 541-955-0363 9-5 pacific coast time Evan

Thank you. I may give you a call once the wiring is done if this thing is still acting up.

 

[magnummopar]

When you say you can get it to run, do you mean it wont run or wont turn over? If it wont crank, then its the black/white not grounded and if it starts and dies or wont start at all, its a different issue all together. On OBD I systems, when they have a bad crank sensor alot of the time, they wont fire at all, unlike an OBD II which will run for 2-3 seconds then shut down. Look at the two crank plug pin outs and compare pin 1 to 1 2 to 2 etc....they will give you wire color on harness side as well as wire order on sensor side. The first thing to check if it cranks but wont fire is ASD relay sending power to fuel injectors and coil. Dont probe the negative side of either, just check for power on green/Orange wire. It should have power for 2-3 seconds after you turn key on then go away until it cranks and PCM receives crank signal.

 

[dartslantsix]

When you say you can get it to run, do you mean it wont run or wont turn over? If it wont crank, then its the black/white not grounded and if it starts and dies or wont start at all, its a different issue all together. On OBD I systems, when they have a bad crank sensor alot of the time, they wont fire at all, unlike an OBD II which will run for 2-3 seconds then shut down. Look at the two crank plug pin outs and compare pin 1 to 1 2 to 2 etc....they will give you wire color on harness side as well as wire order on sensor side. The first thing to check if it cranks but wont fire is ASD relay sending power to fuel injectors and coil. Dont probe the negative side of either, just check for power on green/Orange wire. It should have power for 2-3 seconds after you turn key on then go away until it cranks and PCM receives crank signal.

Here's a video of what it is doing. The next day I tried starting again and it wouldn't run, just a fire chug chug die.

[ame]https://youtu.be/bvFQtO-0-GU[/ame]

 

[dartslantsix]

I posted in the other thread (magnum swap starts but does not run) that I got the engine running. I went through all the wiring and swapped in a manual trans PCM and it started.