LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Swapping Engine/PCM harness?

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Old Aug 31, 2011 | 11:34 AM
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Default Swapping Engine/PCM harness?

I am resurrecting a previously stolen 97/M6 Z28,...the motor and trans was taken and the harness is there, but a number of the end plugs have been cut.

I have installed a complete pullout from a 95/M6 that came with a perfect harness and PCM

I want to run the OBD1 PCM and am wondering if I should just swap in the perfect OBD1 harness?.

How hard is it to get to the in car plugs?

Last edited by TIIMuch; Aug 31, 2011 at 11:49 AM.
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Old Aug 31, 2011 | 12:28 PM
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It's a fairly easy swap, only concern is inspection time when they plug in scanner for obd2.
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Old Aug 31, 2011 | 09:46 PM
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I started into the harness swap, pretty easy, some tight quarters around where the PCM would normally sit, prying the harness hold downs off,...from the uninstalled harness I can see that the plug ins IN car must be close to the front pass door/under dash area.

I've got three scrawny(small) wires which were cut on the in-car side that I will have to find/splice together. Otherwise the OBD1 harness looks perfect,...I rewrapped the loom protectors/cleaned all the contacts etc.,...
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Old Sep 19, 2011 | 12:34 AM
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Super easy swap,...all the connectors are right under the passenger side glove box.
You need to take off the plastic panel that covers under the passenger side dash and the plugs are right here.
I have a tuner cable for the 95/OBD1 Z28 that uses the OBDII style plug in under the steering wheel/dash,...I'm thinking I should be able to tune the OBD1 computer with my 95 cable in the 97 Z28,....?!?!?!?!?!?!?!?!
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Old May 29, 2012 | 02:21 AM
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Well to actually get the motor to RUN it took a bit of work,...the 95 harness/motor I am running in a 1997 F body arn't plug and play.

Again thanks to Shbox.com for connector faces diagram and another thanks to LT1Swap.com for other info on the PCM pinouts.

It took a lot of studying and a couple trials to get it working. I came very close to rebuilding the hacked 1997 harness after putting a couple days into changing/swapping pins on the 1995 harness.

It turned out my main problem was with getting power and grounds to the OBD1 PCM.

Once I got that figured and tested with a digital multimeter the motor fired right up.
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