Conversions & Swaps LSX Engines in Non-LSX Vehicles
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Transmission wiring 4L80E

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Old Jan 6, 2012 | 03:12 PM
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Default Transmission wiring 4L80E

I am swapping an LSx into a 93 Camaro with a 4L80E. I decided to do the harness myself but have run into a bit of a snag. I posted in the automatic section of the site but didn't get a response, hopefully someone will chime in here to help.

The tranny I got had the wires cut off at the safety/neutral or MLPS as some people call it. I bought a new switch as the pins were welded in and replaced the connectors but in the process I started figuring out the wiring and wonder if I really need these plugs wired up.

Here is my post from the Automatic section, if any moderators or admin want to delete the other post in that section, go ahead, thanks.

Originally Posted by PSI GUY
Okay, I have overcome that hurdle in the build. I destroyed the range/neutral switch to save the connectors, but I have one small issue. The transmission came from a 2001, but my wire harness is out of a 99 as well as my pcm. Now, I have the two diagrams, but my question is do I need to have the second 7 pin connector hooked up running it as a standalone? There are no connections to the ecu, i believe it is only for starting and apparently reverse lights. Here are the two connectors, I already traced the four pin connector wires to the ecu, just wondering what to do with the second connector?



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Old Jan 6, 2012 | 07:20 PM
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As far as I know, the PCM does not need those circuits to run the car properly. It's really just the backup lamps and the Neutral Safety Switch (NSS). The NSS keeps the car from starting while in gear and would have to be bypassed to start the vehicle.

However, I would recommend running at least the NSS portion for your safety and especially the safety of others. Just sayin - I'd hate to accidentally run over one of my buddies, or have one of my buddies accidentally run over someone else. That's a negligence lawsuit waiting to happen.

I had my NSS bypassed for a month or two and had a couple close calls. My car started in gear and nothing happened. Then after a second or two of idle it would lunge... no... it would dart forward. I guess if your NSS was in the shifter or something, that would work, too.
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Old Jan 6, 2012 | 07:34 PM
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I do have the schematics, and I will be driving the car on the street, so I guess I'll wire up both connectors, at least it gives a failsafe for the starter circuit and also I will need reverse lights to pass inspection. I sold all my original harness with the LT1 so I'll have to do some grafting to the car to get everything going again.
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Old May 20, 2016 | 02:51 PM
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The back up lamp supply voltage wire (24) according to that diagram...

is that a pin out on the PCM?
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