OEM Magnum swap wiring setup how to?

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player1up

player1up

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I'm posting this here because it's more of a question on the wiring setup.

My 360 magnum swap is physically done, and I'm getting ready to tackle the wiring for the setup so I can get it running next weekend.
The PCM connectors C1 and C2 are fairly straight forward as they are part of the engine harness.
PCM connector C3 ( grey plug ) is part of the main power harness and I'd figure I'd ask what to do with it?

How does the new pcm / power harness integrate into the old harness?

From all of the diagrams I've gathered it seems "easy" in theory, a couple of hot wires and let 'er rip, but I'm sure it's not that easy in practice.
and don't tell me to go buy the $400 harness. I'll figure it out if no one has any "this is what I did" experience and share my results when I'm done...it just may take me a while.
 
I recall several posts with details on the wiring. Did you try searching? You shouldn't need an expensive harness if you have a factory Magnum harness. My guess is provide 12 V constant power, plus IGN (run). You probably need to connect your IGN2 (start) to IGN (run) so you don't lose ignition power while cranking. It probably needs to know you are cranking (feed it yellow "start" wire or IGN2).
 
I have a harness and have been looking over the diagrams, but it seems way too easy...I'm a little preoccupied at the moment installing the rest of the driveline. I'll be tackling the wiring in the next week or so.
Thanks
 
I hear that...but I'm too obsessive compulsive to let it take me that long. :D In the last few weeks I've removed the old slanty, painted the engine bay, installed the new motor, trans, rear end. I still have to finish the fuel system, exhaust and wiring, but the easy part is done :lol:
 
Failed at getting mine cranked today. Going to fine tooth comb it tomorrow. Can't get my relays on my factory fuse box to work. Not sure what's all going on
 
...I'm catching up StreetDak.:lol:...I was shooting for this weekend, but I know if I rush it, I'll screw something up or it'll look like crap...


Tom, I'm using a 360 from a 99 Dakota R/T and a 46RE trans, and a 8.8 phord rear.

I was on the phone with 74TT today and , although it's been a while since he did his, he says there's really only a couple of constant hots and a switched hot
 
I have the Federal version of a 1998 PCM from a manual trans Dodge Ram 1500. I chickened out and bought a Hotwire Auto "hotrod" harness and 24 lbd Ford style 2 hole injectors (the electrical plug-ins are different than the factory Mopar ones).

While the harness looks good on the car, there were some quality control issues with a few wires being switched on the TPS and a bad ground on the pre-cat O2 heater circuit. Because I have a 727 in the car, I used the factory Mopar starter relay etc. This way the PCM does not need to know the engine is cranking.

I combined the start 1 and start 2 ignition ciruits and the PCM doesn't seem to mind.

Due to the knowlege I was forced to learn about the Mopar EFI wiring to be able to trouble shoot the issues caused by the QC problems with the Hotwire wiring harness, I would have done it myself if I were to do it over.

There are a lot of wires, but it's pretty straight forward with a good diagram and pin-out sheets.

I did end up using a post-cat O2 simulator, kept the battery temperature sensor, which measures ambient temperature and am using an SCT tuner from Hemifever. The later sure makes a big difference in performance over the stock tune.

I'll upload some more pics of the actual installed harness shortly.
 

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humm. I am having a issue, I am getting current at the coil and the fuel injectors but I am not getting spark. So the pcm needs to know that the car is cranking?? Is this correct?? Maybe this is my issue
 
Are you measuring voltage at the coil with the ignition on, but the starter not cranking? If so, you may not be getting voltage there while cranking. The factory key switch provides power to the IGN wire in the "run" position, but power to only the IGN2 wire (brown) in the "start" position. If you removed your ballast resistor, jumper the 2 leads together so IGN & IGN2 are always connected. I made the above mistake, ASSuming that IGN got power in both "run" and "start" positions.
 
My ballast was already jumpered as I was using an HEI before the swap, but good point. I think Streetdak had his setup hard wired at first for testing. I did basically the same thing. I connected all of the hots to constant for initial testing.

I got mine fired this weekend! It'll be a little bit before I get the harness cleaned up and documented. i initially had no spark, but it was because I had some of the hots spliced at the PCM and some at the power distribution block and part of the block wasn't getting power ( AND I had forgotten that I unplugged the crank position sensor to get the wire out of the way while installing the trans ) . Unfortuantely the block that was part of the harness I got is broken, so I'll be swapping all of the wires to a new one.
 
Ok, Well, it's taking me a little longer than expected. Between work and an unexpected camping trip I'm behind schedule.
I will say that I have my PCM back from ecuexchange ( they said it was locked out ) and have gutted the Dakota harness and started re-assembly. The harness that runs from PCM connector 3 to the PDC ( power distribution center ) has all of the front lights , cruise control and instrumentation wiring in it. Now you can just leave all of that stuff in there, but apparently I'm an idiot :D and wanted it to be cleaner. At least when I'm all done I'll have a very good understanding of where everything is and what actually needs to be connected for it to run. Oh, yes, there's only 3 wires that need to be jumped in for the engine to start

I'd already be done, but I'm taking the extra time to incorporate a power distribution block so I can use it for things like the fuel pump, electric fan, and such. That is where most of the work has been. I'm actually pulling all of the pins ( not just cutting the wire ) and moving them around to fit my needs.
 
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