66 GTO Backup Light Switch Wiring Harness - How to Route

[jasonjuul]

(I accidentally posted this in the full-size Pontiacs category - sorry)
Hi,

I'm a proud new owner of a 66 GTO with 4spd manual transmission. I'm trying to install a backup light switch but not sure how the wire harness should be routed. I have the switch hooked up and I temporarily fed the harness up through the hole in the floor where the shifter is so that I could connect the switch's wiring harness up to its mating connector. I did this so I could test the switch out. Now that I have it working, I want to properly route/dress the wiring harness from the switch to the under dash mating end. I'm assuming the harness needs to go through the firewall somewhere. The speedo cable goes from transmission to a grommet in the firewall where it passes through the firewall and makes its connection under the dash to the speedometer/odometer. I'm thinking the backup light switch harness has to take a similar path.

Does anyone have any pictures of how the backup light switch wiring harness routes to under the dash or perhaps you could describe it to me.

Thanks a lot, really appreciate the assistance.

-John M.

[Larry]

We have a 1966 Service Manual posted on-line in our On-Line Reference Library.

I did a quick check in the electrical section and there is minimal information (as is often the case). They show mounting, but probably never really considered showing how to assembly something from scratch. However, there may be more info shown in other sections if you snoop around. Many of the sections are quite large, so be patient as they download to your computer.

Sometimes it takes a Body Manual to find exact routing of wiring and we do not have one yet for the '66.

Did you purchase the harness from a reproduction company? If so, could they help?

[jasonjuul]

Hi Larry,

Thanks for replying to my post, really appreciate it. I have the shop manual for 66 Tempest/GTO and wasn't able to find anything useful for performing this task. I bought the backup light switch from Ames Performance and did ask one of their employees but he didn't have experience with this particular issue.

Last night I was under the vehicle and was able to find a small plugged hole in the transmission hump portion of the body (sorry, don't know the technical term for the hump). I sat in the drivers seat and put my hand under the carpet and was able to feel around until I found this plugged hole. It was just a few inches from the gas peddle along the side of the hump. The hole diameter looks too small for the harness connector to be able to penetrate but this hole is in a perfect location for a backup light switch harness. Maybe I'll have to cut the connector off the harness, feed it through the hole, and crimp the connector portion of the harness back on.

I'll do some more research to see if I can confirm I've found the correct entry point. Again, thanks for your help and I will reply to this thread with the information I learn.

Kindest Regards,
John M.