brick12

Was wondering if anyone is able to thin out my harness or has instructions on how to do so. Car is a 86 iroc with 383. Bought the car as a roller no harness so I purchased an 88 ta harness as that's what was able to find locally. Any helps appreciated.

Tuned Performance

iTrader: (92)

Tuned Performance

iTrader: (92)

brick12

Ok thanks that's unfortunate. I'll look Into that link. Does anyone know the pinout for the necessary wires and gauges to possibly make my own?

Tuned Performance

iTrader: (92)

Tuned Performance

iTrader: (92)

brick12

Oh so I dont need the right side harness? I have both the harnesses installed on the left bulkhead that came with the car.

Tuned Performance

iTrader: (92)

brick12

Yeah I re wrapped the accessory harness and the other harness out of the left side bulkhead but thought the gauges ran through the right side harness. Sorry for the confusion electrical is not my strong suit

John in RI

iTrader: (167)

Up till 87 the Engine bay wiring had 3 main harnesses; Engine and Headlight to the C100 ( drivers side firewall ) and the ECM harness to C207 under the passenger side of the dash ( thru passenger side body hole. Starting in 88 the Engine and the ECM harnesses were merged into 1 huge harness. ( some wires were also moved around on C100 and C207 starting in 88,... ) SO; By simply buying a earlier engine bay harness you will remove about 80% of the headache associated with trying to strip the un-needed wires and cutting/splicing to make corrections.

STAY AWAY from 82 & 83 Engine Bay harnesses !!! They are specific to 82 & 83 cars !

84-86 will be the best fit for your needs. ( Carb, TPI, V6 or V8 ) Carb is the best fit,... but the others can be used with minor modification; TPI has no CHOKE circuit, V6 distributor wires might be too short, ect.



You can get a look at the factory schematics for the C100 and C207 Connectors for almost all year / model Thirdgens here: https://berlinetta.info/tech.htm

brick12

Ok so I have the original harnesses for the c100 then do I even need to run the ecm harness then?

John in RI

iTrader: (167)

If you have a pre 88 harness; Nope, probably not. When converting a 87 or earlier stock engine to a non-CC carb the entire ECM harness can be removed. When you do this:

1: If the car is fuel injected you will need to add a circuit for a Carb CHOKE wire.
(**The circuits in the car that have voltage in RUN-BULB TEST-START are the GAUGES, TURN B/U, ECM-IGN, INJ1 and INJ2 fuses.)

2: If the car was TPI than you probably need to splice a connector onto the OIL PRESSURE wire...... Pretty sure this wire ran thru the ECM harness before it reached C100. (IIRC it's a small 2 wire plug from ECM harness to the ENGINE harness. )

3: If your car is a Firebird than you've got to ground the BLACK/WHITE wires on C207 to retain the electric Speedo signal

4: Removing the ECM harness means that you will loose factory TCC lock-up. Either run without TCC Lock-up,... or install an aftermarket TCC lock-up kit. ( I prefer Vacuum TCC lock-up over electric )

Hope that helps !!

brick12

Ok that clears up alot thanks. I have a t5 backing it so tcc is not an issue. And I may just add an aftermarket gauge pod for the oil pressure. Thanks for the help!