HELP Installing Painless TPI ECM Wire Harness
Thread Starter
Junior Member
Joined: Feb 2017
Posts: 17
Likes: 0
From: Los Angeles, CA
Car: 1986 Camaro Z28
Engine: TPI 305 CI 5.0L V8 LB9
Transmission: AUTO 4 SPD 700 R4
Axle/Gears: 3.23 RATIO
HELP Installing Painless TPI ECM Wire Harness
Hey guys didn't know where to turn but here. Inherited this 86 Camaro from my father in law. The OE wire harness was a mess beyond repair, therefore I invested in a new TPI MAF cable harness from PAINLESS i havent connected the cables that run to the ECM or the steering column ill make sure to come here for help too. Problem is the following pictures hah a cables/connectors that I have no clue where to plug/connect or ground them to. I'm a rookie when it comes to grounding cables. Any help is appreciated and if possible pictures are more helpful than diagrams for. And the more detailed in the explanation the better. Any help?
Thread Starter
Junior Member
Joined: Feb 2017
Posts: 17
Likes: 0
From: Los Angeles, CA
Car: 1986 Camaro Z28
Engine: TPI 305 CI 5.0L V8 LB9
Transmission: AUTO 4 SPD 700 R4
Axle/Gears: 3.23 RATIO
Re: HELP Installing Painless TPI ECM Wire Harness
Here are the pictures of the cables I need help with. I have one or 2 more but haven't taken the pictures of them.
Member

Joined: Jul 2015
Posts: 132
Likes: 7
From: Vancouver, Canada
Car: 88 Trans am
Transmission: T56
Axle/Gears: C4 IRS 3.42
Re: HELP Installing Painless TPI ECM Wire Harness
Didn't that thing come with instructions ?
So that is a stand alone harness I think. You may have to do the mods to your C100 wiring that LT/LS swaps do. Does it have its own fuse block ?
But, Heres my guess :
-The VSS wire is intended to go to the VSS buffer (yellow box) that would have been in the original dash IF your car was originally an EFI car.
-The AC wire is probably meant to go to the AC compressor clutch to sense when its activated
-The Fuel pump wire looks thick, Probably meant to go directly to the fuel pump to power it. Does that harness have a FP relay in it ?
-The OIL wires are probably meant to go to the stock oil pressure switch (not gauge sender) That turns on when engine runs to provide a backup method to activate the fuel pump.
-The GROUND ring should go to a good clean spot on the engine (stock was a stud on the back of the cyl head)
So that is a stand alone harness I think. You may have to do the mods to your C100 wiring that LT/LS swaps do. Does it have its own fuse block ?
But, Heres my guess :
-The VSS wire is intended to go to the VSS buffer (yellow box) that would have been in the original dash IF your car was originally an EFI car.
-The AC wire is probably meant to go to the AC compressor clutch to sense when its activated
-The Fuel pump wire looks thick, Probably meant to go directly to the fuel pump to power it. Does that harness have a FP relay in it ?
-The OIL wires are probably meant to go to the stock oil pressure switch (not gauge sender) That turns on when engine runs to provide a backup method to activate the fuel pump.
-The GROUND ring should go to a good clean spot on the engine (stock was a stud on the back of the cyl head)
Thread Starter
Junior Member
Joined: Feb 2017
Posts: 17
Likes: 0
From: Los Angeles, CA
Car: 1986 Camaro Z28
Engine: TPI 305 CI 5.0L V8 LB9
Transmission: AUTO 4 SPD 700 R4
Axle/Gears: 3.23 RATIO
Re: HELP Installing Painless TPI ECM Wire Harness
Didn't that thing come with instructions ?
So that is a stand alone harness I think. You may have to do the mods to your C100 wiring that LT/LS swaps do. Does it have its own fuse block ?
But, Heres my guess :
-The VSS wire is intended to go to the VSS buffer (yellow box) that would have been in the original dash IF your car was originally an EFI car.
-The AC wire is probably meant to go to the AC compressor clutch to sense when its activated
-The Fuel pump wire looks thick, Probably meant to go directly to the fuel pump to power it. Does that harness have a FP relay in it ?
-The OIL wires are probably meant to go to the stock oil pressure switch (not gauge sender) That turns on when engine runs to provide a backup method to activate the fuel pump.
-The GROUND ring should go to a good clean spot on the engine (stock was a stud on the back of the cyl head)
So that is a stand alone harness I think. You may have to do the mods to your C100 wiring that LT/LS swaps do. Does it have its own fuse block ?
But, Heres my guess :
-The VSS wire is intended to go to the VSS buffer (yellow box) that would have been in the original dash IF your car was originally an EFI car.
-The AC wire is probably meant to go to the AC compressor clutch to sense when its activated
-The Fuel pump wire looks thick, Probably meant to go directly to the fuel pump to power it. Does that harness have a FP relay in it ?
-The OIL wires are probably meant to go to the stock oil pressure switch (not gauge sender) That turns on when engine runs to provide a backup method to activate the fuel pump.
-The GROUND ring should go to a good clean spot on the engine (stock was a stud on the back of the cyl head)
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Joined: Sep 2015
Posts: 683
Likes: 19
From: Knoxville, TN
Car: 1988 IROC-Z
Engine: 350 TPI
Transmission: T56 swap ongoing
Axle/Gears: 2.77 9-bolt Posi
Re: HELP Installing Painless TPI ECM Wire Harness
Your best bet is to get a wiring harness diagram for your car, then you'll have a better idea what wire in the car goes to what wire on the harness.
Thread Starter
Junior Member
Joined: Feb 2017
Posts: 17
Likes: 0
From: Los Angeles, CA
Car: 1986 Camaro Z28
Engine: TPI 305 CI 5.0L V8 LB9
Transmission: AUTO 4 SPD 700 R4
Axle/Gears: 3.23 RATIO
Re: HELP Installing Painless TPI ECM Wire Harness
The car does have the fuel pump relay but the harness that connects to these relays is missing and the painless harness did not come with cables or connectors that run to them. Is there a separate harness that run to to the relays where the FP relay is located?
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Member

Joined: Aug 2004
Posts: 228
Likes: 12
From: Ottawa
Car: 86 IROC
Engine: Twin turbo L31 HSR
Transmission: 4L80E in progress
Axle/Gears: 9 bolt 4.11
Re: HELP Installing Painless TPI ECM Wire Harness
You'll find that tan fuel pump wire you want to splice into running from the fuse panel down under the carpet on the driver side under the door sill. It runs into a connector under the back seat. The VSS wire is behind the dash (it's tough getting in there) but you can also find it easier at one of the two connectors (C207/C221) up above the heater box in the passenger footwell. There's a two or three prong sensor at the back of the intake. Thats where the oil pressure connectors go on. Check out Austinthirdgen. org for wiring diagrams and also check online for the instruction manual that Painless has for their complete TPI wiring harness, it has a better explanation. I installed the complete engine harness this winter, took some time and a bitt of guess work (because it's universal ) but everything you've got there does fit.
Joined: Aug 2009
Posts: 1,972
Likes: 127
From: Los Angeles
Car: 1989 IROC Convertible
Engine: 350 TPI L98
Transmission: WC T5
Axle/Gears: 3.42
Re: HELP Installing Painless TPI ECM Wire Harness
You REALLY should contact Painless. Get that diagram. The labels on the wires are not enough. For example, you need to know where in the fuel pump circuit that wire goes.
Member

Joined: Jul 2015
Posts: 132
Likes: 7
From: Vancouver, Canada
Car: 88 Trans am
Transmission: T56
Axle/Gears: C4 IRS 3.42
Re: HELP Installing Painless TPI ECM Wire Harness
That's the stock MAF power relay, MAF burn off relay, Fuel pump replay, and ESC module you have there. Good, You will probably need all those. The relays all look like the 'older' square body style. That bracket mounts to the firewall by the brake booster.
The stock engine harness would have plugged into those and the C100 connector close by on the firewall. I am guessing you will have to create your own wiring from those relays to go to the painless harness.
Do you have any of the C100 plug and wiring ?
The wire that powers the in-tank fuel pump would have come out of one of those relays and then into the C100, and then back through the interior of the car. Does your car still have that wire intact ?
Last edited by 88Greg; May 20, 2017 at 10:49 AM.




