How can I run a new charge wire from a sealed PCM unit? No where to power my system?

[DidUHearThat? 10+ year member]

I just installed a 2nd battery and isolator for my audio system, but there is no where to tap a new charge wire off of the alternator. It has an external sealed PCM unit with an 8 gauge wire comming out the back to the main battery positive.

Where can I tap a new charge wire for my isolator? I've already upgraded the 2 grounds and run the rest of the system. I had taken the charge wire from the main alternator positive bolt, but that bypasses the PCM, and I've been told that is bad, and will fry my alternator. So I have disconnected that.

So now I have this whole system installed, but no way to power it.

Any ideas?

It's a '94 Dodge Grand Caravan, 3.3 L V6 AWD, with stock 90 amp alternator. I'm running about 700 watts RMS of audio, plus the second battery. All new wiring is 4 gauge.

Thanks.

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[DidUHearThat? 10+ year member]

 

[jdawg 5,000+ posts]

the big ring that sticks out to the side it the power to battery, I guess Im not sure what you are asking

 

[DidUHearThat? 10+ year member]

That's a negative chassis mount. It shows continuity to chassis, does not show power when the alternator is running. I wish it were that simple.

I'm trying to find a place to mount my new wire to the isolator. There is a short wire from the only hot bolt on the alternator into the PCM, then it comes out the back of the PCM to the battery.

Where can I mount my new charge wire? If I mount it in front of the PCM, I'm bypassing the PCM, but there is nowhere behind it to attach to without cutting and spicing the 8 gauge wire to the battery.

???

 

[DidUHearThat? 10+ year member]

???

 

[mokedaddy 5,000+ posts]

Pics of alternator?

 

[DidUHearThat? 10+ year member]

 

[DidUHearThat? 10+ year member]

 

[jdawg 5,000+ posts]

ahh youre right, I have like 4 Chrysler alts sittin here and on all them that ring goes on the pos stud

there should be another stud on the alt somewhere

 

[DidUHearThat? 10+ year member]

There is only the main positive out (number 4 on your diagram). I was going to use that, but then that would bypass the PCM module and I was told that would probably kill my alternator.

Where would you suggest I connect my new cable to the battery?

 

[jdawg 5,000+ posts]

to the battery or alt doesnt matter, you are not bypassing the pcm, the alt is controlled by the pcm, the volt reg is in the pcm. The 2 small rings are the feild wires that go to the pcm. No matter where you connect your power the alt is only going do what the pcm tells it to. The box you see on the alt is only a casing for the wires, there are no electronics in it.

 

[DidUHearThat? 10+ year member]

Just to be clear... point #4 on the diagram would be the correct place then? That is what I orginally had hooked up, but I removed it after I was told that would ruin my alternator. So that info was incorrect?

Generally I'm pretty good with electronics, I just don't know much about cars.

I'll wire it all back up again tommorrow.

Thank you.

 

[jdawg 5,000+ posts]

yea that where I would put it, or on the battery. That wire runs from to the alt to the bat so it wont make a difference

 

[DidUHearThat? 10+ year member]

The wire I'm using is much thicker than the factory wiring, so I'm making this part of the Big3 upgrade. Alt to isolator, then isolator to both batteries, plus grounds, should make for a much improved electrical system.

Thanks again.