Ive have searched quite a bit however throughout 7 years and multiple engine, transmission, steering column, 2 vs 4wd options... I cant seem to find concise information.

I just cannot make heads or tails of the reverse light circuit.

Truck - 1974, 2wd, automatic, camper special, "dealer installed" AC

Things checked...

Bulbs - GOOD
Fuses - GOOD
Grounds @ sockets - GOOD
Brake lights - GOOD
Park lamps - GOOD
Turn signals - GOOD

What I've found thus far...

NO voltage @ the socket when ignition is ON with column shifter in REVERSE

I have read about and located a plug on the drivers side splash guard which has the factory installed jumper wire. No voltage present under any condition.

I have located the trailer plug style connector under the column. When unplugged there is 12v present on one pin of one side of the connector at all times. I believe this connects to the switch on the column.

I have the wiring diagrams from fordification. I am having a great deal of difficulty understanding the reverse circuit what with all the variations of the wiring on the same diagram.

The hot wire appears to somehow share or splice another hot wire that leads to / through the wiper fuse / switch...?

I am kind stumped. I am a slender man but not as flexible as I used to be. working under the dash would be a challenge for a small child.

where should I start? look next? test next?

Back up lights would be handy.

Thanks in advance...,

 

does the neutral start portion of the switch work? (crank only in park and neutral?)
if you have 12 on one black-red, do the reverse lights work when you connect a jumper to the other black-red wire in that connector? if so the switch is either bad or needs adjusted (if it cranks only in p and n, more likely a bad switch on the reverse lights portion)

 

The truck will only start in Park and Neutral

is the attached plug you are referring to trying a jumper on?

 

like so?

 

NSS location (and it is the reverse light switch also).

"When the trucks came with a manual trans, there was a dummy plug used to bypass the NSS switch. I've never been able to come up with a part number for the dummy plug. To bypass the automatic set up: Unplug the switch and discard or ignore. There are four wires in the harness plug, two each, red w/ blue trace and black w/ red trace. Run a jumper between the red/blue and red/blue, do the same for the black/red. That completely bypasses the NSS switch. Your truck will now start and the back-up lights will be permanently on.

Now on to the backup lights.
In the engine compartment is a little U shaped jumper wire. It'll be located on the drivers side splash pan, just in front of the firewall where the wiring harness comes through. Unplug the little jumper, this will shut off the back up lights. There should be a back up light switch on the trans cover. (for a manual trans) Run two wires from the switch to the two wires that were jumped. This will get your back up lights working again.
Just a note, you could make a jumper plug out of the NSS. Cut the switch off the harness and splice the two pairs of wires. I just hate to cut these switches up. New, they're getting pricey. Here's the little jumper in the engine compartment.
EDIT: If you don't care about the back up lights, just jumper the red w/ blue trace wires. This will by pass the NSS but the back up lights won't work."

 

thank you both!

So last night I wasn't able to get a good look at the switch. I had been laying down on the floor pan most of the day and was just too stiff.

Nor could I reach behind it with my test light or meter probes to check voltage.

This morning I was able to reach those little screws.

First I jumped the wires as dlburch said. Checked voltage at the sockets and all was well. Cleaned the sockets and bulbs.

I removed the switch, cleaned the contacts and operated it. Plugged in, operated and it worked! Lights as normal!

Was able to get the switch back and adjusted.

Thank you so much!

 

Make sure you did not over tighten the 2 short screws, and you can add a hose clamp around the column and across the screw heads and the L shaped part of the switch mount bracket to keep the screws tight and keep the switch in it proper position. Vibration and time can loosen the screws. Glad you got it fixed.

 

I tried to snug them down, just snug. I get nervous any time I see those coarse screws on this truck.

I that is an excellent tip on the hose clamp and I'm definitely going to throw one on today.

 

Yes once that are stripped your only option is a touch of JB weld, upsize the screw. Or you could of also put some Loctite thread locker on them (before you put them in) yea I know now I tell ya. The hose clamp might be redneck, but it beats a couple of stripped screw holes or 2 screws that loosen up and the NSS gets out of adjustment and malfunctions at the worst time.