85SE 2.8 Izusu 5 Speed. The car was an auto - converted to the stick. I modified the auto engine harness to the new reverse switch location, and the VSS. So the wiring of the car doesn't extend the reverse switch wires to the console like a 4 speed. There were different wiring harnesses for the stick vs auto I assume. So my autodimming compass mirror ($5.00 ebay) needs a lead from the reverse lights to make it not autodim in reverse. (Yeah I didn't realize that they turned it off either but it does make sense) I also need to replace the reverse switch in the tranny but that's a different thread.

Anyways here is the question - What is the best way to extend the wires to the interior? I like things that look factorish. This is a driver so it doesn't have to be pretty but I do like to do things right. Can I add wires to the factory bulkhead? Would I just be better to drill a new hole? (not how I would like to do it) I did a search but didn't see an easy answer.

I have already modified the interior wiring harness to add the clutch safety starter switch, and the cruise control clutch switch. I pulled the wiring harness from the donor car but after seeing how difficult that was I decided that swapping the harness wasn't worth it and modifing it would be a better choice.


Thanks for the replys

Oh also I didn't see any need for that stupid idiot shift light if you're wondering!

adding wires to the factory passthrough is not hard to do, it does take a bit of prying to separate the two halve once the clips are released.

So the glue looking stuff in there isn't too nasty to get through?

Its possible on my car to thread wire from the engine bay into the cab by going through the area above and behind the seats (around where the top seat belt anchors are and behind the plastic trim. The wire comes our in the engine bay by the front of the engine vent bracket.
It may be that you cant do it on a standard Fiero , im not sure (my car has a fino body kit).

Failing that it is easy enough to drill a discreet hole in the firewall to thread a wire through.
But if you want it to look really neet and 'factory' then you could always remove the main harness add the wire in then feed it all back through the factory orifice, personaly i'd say that is far to much trouble just for a couple of small wires.

Well I am thinking factory bulkhead but I just wasn't sure how hard it would be to get through the glob of whatever that seals it. Not sure if that makes me kinda anal but I just hate looking at my loved one and seeing something that just isn't right.

You could probably sneak a few wires through the shifter cable grommets. It won't look factory, but is simple and easy.

I just ran several wires for my electronic guage cluster. I removed the center console, and drilled holes, and ran the wires through a grommet. I have small grommets that fit tightly into a 3/16" hole. I drilled the hole just above the computer, between the connecters. I drilled mine about 1 1/2" above the computer. Double check yours. Maybe you have something that would be in the way? Mine did not. I also use a magnet to catch any metal shavings coming off of the drill.

When I did the run down the console, through the shifter, and up to the guage pod, I removed the factory tape on the console skeleton, ran the wires through the valleys, then retaped them with black duct tape. A few zip ties, and the job is complete, hidden, and quiet. I might add, that I wrapped the wires like a harness. No future chafing.

I ran my amp wire the same way. Just with a much bigger grommet.

[This message has been edited by Tony Kania (edited 03-31-2010).]

Try to use the bulkhead connector. The connector itself comes apart with some difficulty but the goo that GM used to seal mine looked like cheap glue but it came apart with a heat gun. You should be able to get a wire or three through there with no problem. I'd recommend more wires than just one for future expansion if you think you might want to install other goodies.

I am not sure I follow what you are after...

If you converted an auto Fiero to a manual (isuzu), then the reverse light switch is still tranny mounted and all you need to do is cut the wires from the flat black connector on the automatic transmission and splice in the needed connector for the switch on the isuzu.

If you want to tap into the back up circuit inside the car, the easiest way is probably to use the TCC wire that is no longer used (and is right by the reverse switch on the isuzu). Splice it into the "light" side of the switch so it sees 12 volts when in reverse. This wire will need to be removed from the ecm in the console, but with a manual it is not needed anyway.

quote Originally posted by fieroguru: I am not sure I follow what you are after... If you converted an auto Fiero to a manual (isuzu), then the reverse light switch is still tranny mounted and all you need to do is cut the wires from the flat black connector on the automatic transmission and splice in the needed connector for the switch on the isuzu. If you want to tap into the back up circuit inside the car, the easiest way is probably to use the TCC wire that is no longer used (and is right by the reverse switch on the isuzu). Splice it into the "light" side of the switch so it sees 12 volts when in reverse. This wire will need to be removed from the ecm in the console, but with a manual it is not needed anyway.

That! is what I am looking for! Thanks. Now I have to dig that wire out of where I cut it off the harness and splice it to the light switch. (and do the inside too)

A big drill.



That's what I do.

Just drill it. Start with a ~1/8" pilot hole directly between the two wire harnesses above the computer behind the console--there's nothing here for you to worry about drilling through. I reamed mine at least big enough for a pair of RCAs to fit, so probably ~5/8". Use some wire wrap and follow the factory wiring--it'll match perfectly with the OEM wiring.