Ok, so I'm doing a 4cyl to 2.8 (bored to 3.1) conversion for my brothers 85 2M4 5spd and we're down to the final little nitty gritty details to finish up this swap. We're mating the 3.1 to the stock Isuzu transmission from the car. One of the issues I'm having to figure out is the backup lights are not working. I believe the back up switch in a 4spd is in the shift select bracket in the console and the 5spd Isuzu switch is in the transmission. Can someone confirm that and has anyone done a similar swap? What did you do to resolve this without completely rewiring the backup light?

------------------
87 Fiero GT 3.4 Pushrod with 7730 ECM & DIS
88 MERA #8013
85 Fiero SE with 3.1 pushrod
86 Fiero SE 2.8 stock
http://www.youtube.com/LostNotForgotton

You're correct about the placement of the respective switches. Easiest way would be if you had an 86 engine with it's harness. The 86 V6 was wired both ways. I've had 2 85's converted to Isuzu's and they jumpered the harness in the console but I don't know what they did to power the switch at the transmission. I assume they had to run a new wire back to the switch. I just never payed attention to what was done. I believe he powered the transmission harness off the C500 near the battery. I remember an extra black wire that had been inserted there.

One of them was an 85 with 85 harness and the other was an 87 engine into an 85. The 87 engine had an 87 engine harness, so that one was probably plug and play.

Be sure you upgrade your clutch and pressure plate to a V6 package. You'll need to use the Isuzu throwout bearing, though.

[This message has been edited by fierofool (edited 01-30-2015).]

Second what fierofool said.
The Isuzu (and Getrag) both have the switch on the tranny. The 4 speed Muncie uses a switch on the shifter.

Since the 85 2M4 came with an Isuzu tranny, your original harness should already have the the wiring for the tranny-mounted reverse light switch.
I'm guessing you're using a V6 engine harness, which may or may not have the wiring for that switch.
You can un-pin and reuse the switch wiring from C500 if you trace the wires, or you can just add a new connector and wiring to your V6 harness.
It should use the same pins for the 4 cylinder and V6 applications.

[This message has been edited by Raydar (edited 01-30-2015).]

Ironically the engine and wiring harness I'm using for the swap came from an 86 GT. Thanks for confirming the switch location. I was able to locate the connector on the harness and plug it in to the transmission. The lights still aren't working but I didn't do anything to diagnose the problem. Last weekend was spent at the Philly Auto Show so I didn't have enough time to really mess with the car other than locating the connector and plugging it in. As long as the weather holds out next weekend maybe I'll try and swing by and diagnoses the problem further.