Wiring harness confusion
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Junior Member
Joined: Jun 2009
Posts: 61
Likes: 1
From: Va. Beach
Car: 89 Iroc
Engine: 350 Carb
Transmission: 700R
Wiring harness confusion
I have an 89 5.7 TPI im converting to carb. I have a brand new crate 350hp I just dropped in. I had the 700r4 rebuilt with a non-lockup converter so Im not concerned with the tcc switch. I keep reading different opinions when it comes to the wiring harness. Ive heard some say to take it out and others say to leave it in and cut out later. If I'm disconnecting the harness from the computer anyways then what good is it to leave the harness in? Im going to use the oem fuel pump with a fpr. Is it best to wire the fuel pump to the ignition or the alternator? Not an expert at this so any help would be greatly appreciated. Thanks much.
Joined: Mar 2000
Posts: 43,187
Likes: 43
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Go ahead and remove the ECM harness. Cutting doesn't make a lick of sense to me. There is always someone out there who needs an unmolested harness.
Wire the pump relay to battery power. Use ignition switched power to energize the relay.
Wire the pump relay to battery power. Use ignition switched power to energize the relay.
Thread Starter
Junior Member
Joined: Jun 2009
Posts: 61
Likes: 1
From: Va. Beach
Car: 89 Iroc
Engine: 350 Carb
Transmission: 700R
Re: Wiring harness confusion
Can you tell me what to do with the two heather hoses that come out the firewall and into the plastice piece? I got the harness disconnected from the computer and through the wheel well. Im just concerned about taking out a wire I need and keeping everything else functional. Any advice?
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iTrader: (4)
Joined: Mar 2009
Posts: 3,079
Likes: 4
From: Pepperell, MA
Car: 1987 Trans Am
Engine: LQ9/L92
Transmission: 4L60E
Re: Wiring harness confusion
If you don't have an ECU (computer), the entire passenger side harness can come out. There should be no wires that you need to worry about reusing.
As for the heater hoses, those are for your heater core, don't get rid of those. Unless you don't want heat in your car. Then you can think about it.
As for the heater hoses, those are for your heater core, don't get rid of those. Unless you don't want heat in your car. Then you can think about it.
Thread Starter
Junior Member
Joined: Jun 2009
Posts: 61
Likes: 1
From: Va. Beach
Car: 89 Iroc
Engine: 350 Carb
Transmission: 700R
Re: Wiring harness confusion
Which one is the pump relay. There are 3 or 4 relays on the drivers side? Then I wire the pump relay to the ignition?
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