Willtrax

Hey everyone, I've got a headache on my hands at the moment. My 1979 F-150 Super cab is starting to show the fun of having a older truck, but you know what I wouldn't get reed of it for anything in this world.

I've been trying to find out what is going on with my brake lights and
hazard lights, neither one comes on. Turn siginals work tho. I've checked all the fuses, checked the grounds behind both lights in the rear of the truck, checked the brake pedal switch and replaced but don't think that was a problem. It seems as tho the problem started after I started pulling a trailer behind the truck. I had a local trailer dealer install a light harness for the trailer. I don't know if it had screwed my brake lights up, they had been working great for roughly a month until today.

There was a guy behind me on the interstate and I was coming up to a accident and had to hit the brakes to slow down and this idiot behind me kept coming, later realizing that I had no brake lights I couldn't be pissed at the dude.

If anyone knows older F Series trucks and could point in the right direction that'd be great. Because the interstate situation was spooky. And no I don't mean Busch Gardens / Hall-O-Scream spooky. HAHAHAHA

Willtrax

Forgot to mention that the reverse lights never have worked since I had the truck. Had the truck from 2008.

eagle1978

there's several causes this is happening. Get a helper and check for voltage at the bulb sockets using a test light. Also, you said you checked your grounds, what kind or readings did you get when you did this?

Willtrax

I didn't test them with a meter. Just cleaned the connections and made sure the frame where it meet was clean as will.

I can't say I know the correct way of really using a meter. I know to set it to DC power not AC. I guess from there I just put the red probe in the socket of the light and black probe to the frame for the ground correct?

Or take a light bulb, because I don't have a test light, and stick a wire around the outside of the light bulb, would be the ground and the point at the end would be the load wire?

FOMOCO466

I'd bet to say that the issue is right up next to your power booster...there is a connection there where two wires run into one..I had a issue where I wa smelling a hot wire and ended up tacking it down to that.. it's a power wire that goes to the rear lights. I don't have the truck anymore, but if you follow the thick RED wire from the back of the IGN switch it runs up forward, then goes to the back of the truck..the connector on mine was getting melted!..I cut out the plug and spliced them together after I fixed the issue (issue was the trailer place installed my new tounge jack and the bolts going over and under the tounge of the trailer were pinching the power wires, so everytime the trailer was hooked up and I turned the lights on or hit the brakes it caused a short)

Willtrax

That makes sence. I don't have a power booster for the trailer tho. It's just a 8 way to a 4 way to the lights on the trailer, no brake-away.

FOMOCO466

no no no...the connector that deals with the lights is next to the power brake booster on the truck...

81F150

Also, when those guys splice into your wires they use those cheap little piggy-back crimp on things...these can cut your wire in half. They will work for a while but as the insulation stretches where it is crimped the wire inside will seperate and they wont work anymore. Hard to explain in text, but check your connections for the trailer harness.

Willtrax

True indeed. They used a couple of those crimp style connectors. I know what you mean in regards to the stretching of the wires. The crimp goes thru and around the wire, tectonically. But sometimes cuts the wire in half depending on how many wires are in the wire itself.

Willtrax

I took the truck up to a local mecanic and he looked it over for two days. After checking it from the fuse box, thru the wires to the socket. He said the only thing that was wrong was the clip in the fuse block was almost broken off for the inside of the block. That was the only thing. So now the truck is legal again.


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Thanks for the help ya'll