Can anyone give me the location of the backup light switch on a 78 F100 with a 302/C6 combo? My backup lights have mysteriously quit working (changed bulbs). Also, I have a large unattached white wire that goes out of the firewall and down the frame towards the transmission, not sure of where it ends, but any suggestions as to where it should be reattached? I think the previous owner some how used it when they changed the radio.

 

My '79 C6 has a Neutral Start Switch that controls the backup lights. It's on the driver's side of the transmission.

Didn't figure a 302 would mate with a big bellhousing C6...interesting!

 

I assume (and I hope that the old assume saying will not be true for this) it is a C6, the pan is "L" shape and not square.

 

Sounds like it...wasn't implying it ain't a C6. I'm still very much a and am learning something new every day!

 

I only had Chevy's when I was a teenager, my first Ford was in 1994. So I know absolutely jack squat about a Ford. I have looked through the Repair Manual but never imagined that the neutral switch could be the location (mine works so maybe it is something else).

 

I'm "passively" trying to figure out why my reverse lights ain't working, too. Replaced bulbs...fuses look good. Multimeter says I'm not getting any juice back to the bulb. The "Neutral Start" part of the NSS works as intended, however. She won't turn over unless its in Park or Neutral. So I don't know if the reverse light part of the NSS is busted, or if I've got a short somewhere in the wiring going back. Haven't figured that part out.

Good luck!

 

Each turn signal has a ground wire attached to the body, you might check them to see if they are broken or corroded.

 

Saw that on the wiring diagram...is gonna be my next check. Thanks!

 

I found this posted by numberdummy on a similar topic:

"On 1978/79's the NSS (C6: D8TZ7A247A Motorcraft SW1489) is located on the transmission.
Before I'd buy that 100 dollar (!) NSS for the '76, I'd check that lever. I'll betcha the end has broken off, or it has lost tensile strength, and popped out of the shift tube."

That "lever" he mentions is apparently what moves the switch and it's common for it to break off.

My back up lights didnt work either. It's a 77 so the NSS is on the column instead of the trans. I replaced it and that fixed the problem.

 

I have a 78 and I think my NSS is located on the steering column.

 

The Bellhousing for a 302 with C6 is different than the bellhousing with a 390 with a c6 as example. The flexplates are different too...


The NSS mounted on the tranny are notorious for going out due to oil contamination. Check to see they are clean and free of oil.

The wire colors for the NSS are...

White/Purple: Main power to NSS for Backup lamps. Fuse-11 Make sure this fuse isn't burnt. Replace if in doubt. Hot in run.
Black/Red: Switched backup lamp power to illuminate the bulbs.
Red/Lt. Blue: Starter Solenoid wire from ignition switch. Hot in start.

A good test would be to jump the white/purple and black/red wires together at the NSS connector. with the ignition switch in run. If the backup lamps light, it's the NSS switch at fault.

Make sure you disconnect the red/blue wire and the brown wire at the starter solenoid before you do your tests to make sure the truck doesn't start on you when you are under the truck. Don't forget to hook them back up when done.

 

This is the column monted one: Up to 77 mounted on the bottom of the steering column




And this is the transmission mounted one: After 77 located on driver's side of transmission.

 

Unless the steering column has been swapped with an earlier model, this is incorrect.

1967-1977 and older if equipped: NSS is mounted on the steering column.

1978 and newer the NSS is located on the transmission itself.

 

Does anyone have a pic of what their C6-mounted (78/79) NSS looks like all hooked-up?

 

Not mine but heres a pic