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Discussion Starter · #1 ·
I know many of you are going to tell me to look harder but I have honestly looked to the end of the internet and back, I have been flamed for ressurecting old posts so I'm going to make one that entertains my build.

I have a 1986 S10 and I'm trying to finish up my 305 TPI swap. The engine came from a 1989 firebird and I have everything OEM. I have both my 2.8 TBI and 5.0 TPI wiring diagrams and breakouts but to be quite honest, even as a third year electrical apprentice I'm having trouble making sense of what wires I need to connect to make my engine turn over off the S10 ignition. Aswell as Im somewhat confused on how I'm going to power the Body electronics. I guess my question is; do I have to splice my TPI harness into my TBI connector and just rearrange the PIN outs.

Example, If B1 on the TBI harness pinout was ignition, but on my TPI it was B7 do I just need to make B7 from TPI harness B1 on the TBI harness. I might have made an absolute mess of this question, I have searched this whole forum, either direct me to my answer and Ill delete, or humble me please I would love to fire this TPI 305 in my s10 before winter. Am I over thinking this and do I just need to run 12v to some of the things that need constant power and forget about the harness clipping into the firewall c100 breakout. Any info is greatly appreciated
 

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I did a TPI into a 94 pickup 20 years ago. I bought the S10 wiring diagram book off ebay. The 89 Camaro FSM has a good electrical section. You will need to run the 1989 Camaro ECM with the correct 305 TPI chip in it.
It's been a long time, but I don't remember much of an issue with the cab wiring interface. Not like the newer models. Everything was still analog 1 wire 12VDC. No 5V. No data. Don't cut out any unused wires. Just wrap them and tuck back into the looms. 2 years from now when you change directions on the build you'll thank me.
Here's a link to the type of GM manual I'm talking about. Very thorough and detailed. The example is a 1990 and not what you need, but it'll show you how detailed they are if you look at the last pic.
Unfortunately I don't see an 86 currently listed on ebay. One will show up.
 

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Discussion Starter · #3 ·
I did a TPI into a 94 pickup 20 years ago. I bought the S10 wiring diagram book off ebay. The 89 Camaro FSM has a good electrical section. You will need to run the 1989 Camaro ECM with the correct 305 TPI chip in it.
It's been a long time, but I don't remember much of an issue with the cab wiring interface. Not like the newer models. Everything was still analog 1 wire 12VDC. No 5V. No data. Don't cut out any unused wires. Just wrap them and tuck back into the looms. 2 years from now when you change directions on the build you'll thank me.
Here's a link to the type of GM manual I'm talking about. Very thorough and detailed. The example is a 1990 and not what you need, but it'll show you how detailed they are if you look at the last pic.
Unfortunately I don't see an 86 currently listed on ebay. One will show up.
So, do I need to mess with changing the wires out in the connectors? I have my TPI original ecm, Im talking on the "Clip" side that goes into the breakout.Do I need to use the end of the s10 harness to make it plug into the firewall, or skip over that and just put power to the ECU and find the ignition wire and link it to my s10 ignition. I may not be coming off clear but I truly appreciate your time.
 

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I added a little fuse block on the firewall for the B+ and Ign. power. Hooked directly to the ECM. All your gauges should stay as they were. Just take the old senders and put them in the 305. I did have to run a wire from the ECM to the cluster for the SES light. Just connected the original wire to the correct pin on the TPI ECM. Do you have A/C? If so the ECM will need an A/C wire to adjust the idle when it's on. That's all in the wiring diagrams.
It's usually off the low pressure switch to account for cycling.
 
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