Hello everyone! I just picked up a 92 F150 XLT and I'm running into a problem with the electrical for my tow. I got a voltage meter to check the wire harness in the back and got nothing. So looking at what others had problems with I checked the fuses. This is where I'm really confused.

The fuse box under the hood I notice that slots 6 and 7 (bottom left section in the picture top 2) both do not have a fuse in them. I also noticed that the metal slots the fuse is suppose to go into is not there either. Is there a reason for this? I had to tow a trailer today, but held off until I can figure out why I can't put in any fuses there. Please help!

 

That means your truck did not come from the factory with a towing harness. You will be better just tracing the wires to find out where they tapped it. Most likely they are tapped into the tail lights.

Actually, looking at your pigtail, it is tapped into the tail light harness.

 

Is there a reason why the 4 tow connection does not work if my tail lights work? Thanks

 

Have you plugged a trailer in, or just used a tester? I had the same issue with my Flex, would not light up the test lamp, but hooking to a trailer it worked.

 

A 92 F150 doesn't have a computer that controls the trailer lighting and brakes like the newer vehicles

 

True, but neither did the Flex. The test light may not draw enough current to overcome corrosion in the harness though, and thats why my light didn't work but the trailer did. After disconnecting the trailer the test light started to work.

That tap is inline to the tail lights so if the harness was an issue then chances are the tail lights would fail too.

 

So then all I'm going to get from that harness is the tail lights? No brakes or turn signals? Well that sucks

 

You should get tail lights and brake/turn signals.

This^^ Do your truck's tail lights, brake lights, and turn signals work? If so, I would pull the trailer light pigtail and test for continuity on each wire. Look and see if there is actually a ground wire running in that tail light circuit.

Also, when testing with the voltmeter, what did you use for the ground?

 

The computer on the newer models is used for maintaining a list of your trailers and an odometer for each.
If you splice into the correct wires you will have brakes and turn signals

 

Looks like this is what is installed in your truck,

https://www.etrailer.com/Custom-Fit-...FYW6wAodte4Oaw

They are cheap, so you can always just replace it.