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89 firebird 305TBI going to carb ecm harness

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Old May 4, 2013 | 02:31 PM
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weesel72's Avatar
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Car: 85 trans am
Engine: 5.0 carbed
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89 firebird 305TBI going to carb ecm harness

I keep reading that you can completely remove the pass side harness without cutting anything? How is this done? Do you pull the wires loose from the ecm connecters???
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Old May 4, 2013 | 04:22 PM
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t-top havoc's Avatar
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Car: '87 Camaro
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Re: 89 firebird 305TBI going to carb ecm harness

May need to trace & keep --
VSS & fan temp wires, not exactly sure. Ours was done by a PO
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Old May 8, 2013 | 05:26 PM
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From: Camp Lejune, NC
Car: 92 Camaro RS
Engine: 305 Tbi
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Re: 89 firebird 305TBI going to carb ecm harness

I need some insight on this as well...
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Old May 9, 2013 | 08:28 AM
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Car: 86 T/A - 70 Z28/RS
Engine: Broke - 350
Transmission: 700R4 - M22
Axle/Gears: G80, 2.73 - ZQ9 G80 4.10
Re: 89 firebird 305TBI going to carb ecm harness

Go here for a wiring diagram....

http://www.austinthirdgen.org/index.php?pid=19

You will have to cut some wires if you plan on using the in tank fuel pump, like the ECM control lead to the relay. On a TBI car the coolant fan is ran through the left engine harness and the fan switch in the head. Similar to a LG4 carbed car, not controlled by the ECM.

In the interior section you will also have to splice in a ground wire to the vehicle speed sensor buffer. The wires from the transmission speed sensor pass through the ECM bulk head connector so both the interior and exterior wires will have to be cut out. I had to do this on my 86 T/A
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Old May 9, 2013 | 08:43 AM
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weesel72's Avatar
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From: North Carolina
Car: 85 trans am
Engine: 5.0 carbed
Transmission: TH700R4
Axle/Gears: 9 bolt
Re: 89 firebird 305TBI going to carb ecm harness

Originally Posted by bestracing
Go here for a wiring diagram....

http://www.austinthirdgen.org/index.php?pid=19

You will have to cut some wires if you plan on using the in tank fuel pump, like the ECM control lead to the relay. On a TBI car the coolant fan is ran through the left engine harness and the fan switch in the head. Similar to a LG4 carbed car, not controlled by the ECM.

In the interior section you will also have to splice in a ground wire to the vehicle speed sensor buffer. The wires from the transmission speed sensor pass through the ECM bulk head connector so both the interior and exterior wires will have to be cut out. I had to do this on my 86 T/A

Hate to ask, but i will.....any chance of a "step by step"? I bought this car with out a drive train, put in a 350 carbed, and a 350 carbed was in in it. He had a toggle switch for the tcc lockup, but it was at the ALDL, and im not sure that would work since the ecm and it's harness are now gone?? I'm just trying to figure out how to hook everything up....alt, dist, tcc lockup, going with an aftermarket electric fan control, ect. I think i have a pretty good amount figured out, but would be great to have a way to verify, like a step by step? I really appreciate any help! If you lived closer, the beer would be on me! lol!
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Old May 9, 2013 | 09:01 AM
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From: N. Ky
Car: 86 T/A - 70 Z28/RS
Engine: Broke - 350
Transmission: 700R4 - M22
Axle/Gears: G80, 2.73 - ZQ9 G80 4.10
Re: 89 firebird 305TBI going to carb ecm harness

Since the motor is out just start to remove the passenger side harness when you come to something you are not sure about PM me here or you can e-mail me during the week or call on the weekend. If you are interested in that then PM me and I'll send you my info.

The Alt, starter wires, Dist will be nearly the same. I will do what I can. In fact I just got done moving some of my engine harness wires around so I don't have massive wire looms stretched across the intake now.
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Old May 9, 2013 | 02:35 PM
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The ECM is behind the dash on the passenger side. The harness passes through the passenger kick panel. Remove the panels, drop the ECM, remove the connectors from the ECM that go to the kick panel.

The bulkhead connector behind the kick panel has a clip that holds it to the body panel. Remove the plastic fender liner on the passenger side, and you can pull the harness out of the passenger compartment after removing that clip. Then you can remove it from the engine compartment by pulling/guiding it from the fender area.

Anything that it connects to in the engine compartment can be disconnected/unbolted and removed with the harness.

However, part of the harness will go to the transmission for the TCC lock-up. By removing all the stuff above, you'll have to provide that function in some other manner. Kits are available, or you can wire it up yourself.
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