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Old 04-22-2017, 10:07 PM   #1
PunishedC10
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Wiring questions

I have an '85 C10 with an ls1. I bought a harness from PSI conversions and I'm not very pleased. It seems half of the wiring is still up to me. Anyhow, I had to purchase a TCC to lock/unlock the torque convertor. Can anyone tell me the wires best to tap into?
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Old 04-22-2017, 11:29 PM   #2
gmachinz
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Re: Wiring questions

That's exactly why my next build will be an LSx....I'll have a much better harness option for these trucks specifically.
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Old 04-23-2017, 08:19 AM   #3
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Re: Wiring questions

Quote:
Originally Posted by PunishedC10 View Post
I have an '85 C10 with an ls1. I bought a harness from PSI conversions and I'm not very pleased. It seems half of the wiring is still up to me. Anyhow, I had to purchase a TCC to lock/unlock the torque convertor. Can anyone tell me the wires best to tap into?
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What Trans do you have?
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Old 04-23-2017, 01:33 PM   #4
PunishedC10
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What Trans do you have?
It's a 4l80e, I had it fully rebuilt with a Circle D torque convertor and bought the TCC switch from PSI Conversion. I just need to know if there's a wire that is 12V until the brake pedal is pressed and goes to 0V once the brake pedal is pressed.
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Old 04-23-2017, 01:38 PM   #5
PunishedC10
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Quote:
Originally Posted by gmachinz View Post
That's exactly why my next build will be an LSx....I'll have a much better harness option for these trucks specifically.
Don't get me wrong. The harness is really good quality. I just wish they would have ran two relays and did the wiring for the two fbody efans I'm running. They didn't explain that I would need a TCC switch or offer to partially wire it up for me. I will also have to run a wire from the fuse panel to a switched 12v source for the fuel pump. The entire fuse panel needs a 12V keyed on source, so I'm not sure why they didn't supply a wire for the fuel pump keyed 12V when they did supply a wire that runs all the way to my fuel pump/sending unit.
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Old 04-23-2017, 05:03 PM   #6
gmachinz
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Re: Wiring questions

The LS pcm has a fuel pump trigger wire already-white w/blk if I recall. When the PCM gets a switched 12V source, it automatically applies 12V positive trigger on that wire. PSI doesn't have any clue (nobody does really) what kind of fan(s) you plan to run either. The Fbody 4th gen LT1 and LS1 fans are wired in series using 3 relays for low and high speed but nobody offers a variety of ways to runs fans-everyone else typically gives you a big ole relay and that's it.

I have the dual speed fans harnesses w/an adapter to use for your LS setup if you need one. You can have the pcm fan turn on temps turned off and run a stand alone setup-less hassle. PM me if you need assistance on options if you're interested-I can help ya figure some of this stuff out.
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Old 04-23-2017, 05:05 PM   #7
gmachinz
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Re: Wiring questions

Quote:
Originally Posted by PunishedC10 View Post
It's a 4l80e, I had it fully rebuilt with a Circle D torque convertor and bought the TCC switch from PSI Conversion. I just need to know if there's a wire that is 12V until the brake pedal is pressed and goes to 0V once the brake pedal is pressed.
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Just use a stock brakelight/cruise control switch on the pedal and put 12V to it...)
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Old 04-24-2017, 06:24 PM   #8
1957 Chief
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Re: Wiring questions

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Originally Posted by gmachinz View Post
Just use a stock brakelight/cruise control switch on the pedal and put 12V to it...)
What he said. I did the same on my son's 1984 with an LS/4l60.

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Old 04-24-2017, 08:52 PM   #9
Dads79GMC
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Re: Wiring questions

I'm glad gmachinz lives in town; I know I'll need his service on wiring issues at some point. Thanks ahead of time Jabin! Sorry to pop in! Mike
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