hello, my 79 F100 has no reverse lights... any thoughts?

 

A couple of questions:
1) did your backup lights ever work?
2) can we assume you checked your light bulbs (both sides, present, replaced with new/confirmed working bulbs)?
3) do you have voltage at the backup light socket (put a multi-meter feed or "dumb" test lamp feed on each the ground and 12V socket leads)?

Can continue to walk you through troubleshooting once I know the answers to these questions (really #3 is the only one that truly counts, but the others help).

 

bad neutral safety switch? like i jammed a screw in mine so itll start but the only difference between before and now is i dont have reverse lights

 

Well, first I would check the bulbs. Then I'd probably check the sockets at the same time. One of mine was bad.

Not sure which fuse handles the back-up light circuit, but I'd check those.

Then I'd check the switch. If it's a three-on-the-tree, the back-up light switch will be down at the end of the steering column, visible from under the hood. Put the transmission in reverse and observe the levers coming out of the column, and you'll see where the switch needs to be. There are pics on site. Mine had had the switch's bracket bent so that the switch was out of the way of those column levers. That sure was an easy fix...

 

Ck bulbs, #11 fuse, power back there when in reverse?

Standard trans? You have a jumper in the engine compartment. Read below. And yes is can be on the steering column in the engine compartment if 2wd.

Auto trans? Switch is down on the side of the trans where the safety neutral switch is.

"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. 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.

 

No Reverse lights?

My two cents on the subject is to agree with meangreen92 as far as start your troubleshooting with things that are free to check
if you don't have a multimeter GO get one!
Now comes the fun part of owning your truck
1, check your fuse, (77&79F250 gave you diagrams)
2, check your bulbs
3, check the sockets and the connections at the sockets
4, check the ground wire to the tail lamp assembly
5, check the connection at the reverse lamp switch
still no reverse lights?
6,time to trace your wires under your truck, look for PO (previous Owners) handy work..
while your tracing the wires be sure to check and test the OEM connectors,
speaking from experience, just because it looks good doesn't mean it is. after time the wires inside can or will break away from the pin that is molded into the plastic/rubber connector.
if still no luck then I would start with replacing the reverse lamp switch.

this is the three on the tree set up that meangreen92 was describing

 

NSS only used with A/T. 1978/79...it's located on the transmission. C4 used a different NSS than C6.

3 M/T backup lamp switch located on the steering column adjacent to the 1st/reverse selector lever.

Warner T-18/T19 & New Process 435 4 speeds: Backup lamp switch threads into the shift tower.

 

idaho highboy, sorry for the late response. i don't ever recall them working since purchase in 2013... i have replaced the bulbs and nothing seems to be working. a friend of mine helped me test the voltage and i also don't recall that working either...

 

sturm -

that is what i anticipated after researching last month but i have no idea what it does or where it is located on the truck. ��

 

77&79F250, i have a 302 with a C4... or C6, not sure because there was a 347 stroker swap a few years back but that engine died on me. now just a stock 302 but the trans doesn't feel right... probably has a shift kit. anyways i know for sure it is a 3 speed auto

 

dads1977, oh boy lol. well i have looked underneath at the shift linkage and there's a wire coming down connected to something i can't see, it has a white prong with a red. black, and i believe white wire attached to it.

 

In.........

 

3 M/T: Backup lamp switch located on the steering column, adjacent to the 1st/reverse selector lever.

4 M/T: Backup lamp switch threads into the shift tower.

 

so i have to clean it...? how do i remove it??

 

so turns out the neutral safety switch was bad. was the original and after 38 years of service i'd say it did it's job... i ordered one online for $20 and after a 20 minute job of crawling around underneath i now have reverse lights!!