Can someone point me in the right direction to start looking. I have searched but have only found kind of opposite of my problem. I have brake lights that work, but no turn signals or park/running lights. Also while brake lights are on if I turn on signal the light goes out. Would the turn signal switch cause this? It is both sides with no turn signals or tail lights working and only brake lights work. Thanks for any help

 

The parking lights are powered separately from the brake/turn lights. That is just a wiring issue in of itself. Do your front parking lights work? (with no headlights on). If it is only the rear lights you need to make sure you have power and the bulbs are actually good.

The lack of blinking of turn signals could just be the flasher unit. Might need a new one.

 

It's definitely normal for the stop lamp to go out on the side that the turn signal switch is turned to. That's how it lets the signals work when you're also on the brakes. Otherwise when you have your blinker on to broadcast your intention to turn, it would just go solid when you hit the brake pedal.

Now, why it goes out instead of lights, that's another issue. Very possibly it's your flasher unit like Freightrain said. But power is simply not getting to the switch from that circuit.
Could be a grounding issue, but that's not what it sounds like to me.
Can't be the bulbs because the brake and turn lamps work on the same filament.
Can't be the wiring between the turn signal switch and rear light sockets for the same reason. All the same.

Find the two flasher units (one for hazards, one for turn signals) and swap them to see if that fixes the turn signals (unless neither works?) and while you're at it check for 12v on one of the wires to the turn signal flasher.
What about headlights? Are they working?
What about hazards/4-ways? They working?

Paul

 

Head lights work. The hazard lights have never worked since owning the truck, about 20 years. Lol I think it maybe the flasher itself. Had time to look a little under dash yesterday after work before dark and found flasher hanging down and only one wire connected to it. Would that also keep the park/tail lights from working also? Will try and find other wire and hook it back up and see what happens. thanks for all info.

 

The turn signal switch disconnects the brake light to make it flash on the side you choose. I would suspect that inop flasher might be part of the problem. Nothing to do with parking lights though.

Do the front parking lights work(without the headlights on--the front parking lights turn off when headlights are on)? No? I would suggest maybe the headlight switch is faulty or at least the wiring for the parking lights is faulty.

 

Yes the front park lights work. Only thing not working is the rear park lights and turn signals. Reason I am puzzled the brake lights work but not the rear turn signal or park lights on either side. Haven't had time to check anything today. Was just hoping to get idea where to start and any idea it could be. Automotive wiring is my down fall and intimidates me for some reason. Also thanks for the help so far.

 

Yeah, it's most people's downfall I think. Not sure when the light bulb went on for me, but it was all Greek Voodoo for me for a long time.

Because your brake lights work, that means that without a doubt your wires and sockets and bulbs are at least partially good from after the steering column back to the lights. But because the rear frame mounted wiring is subject to lots of abuse during their normal lifetime, I would be looking along the frame first for why the tail and running lights don't work.
Look for any point at which a wire might have been kinked, cut, corroded or melted by exhaust. Unwrap the tape if there is any doubt as to a certain part.
Then re-check the bulbs (you did say you checked those, right?) again to make sure that you're not just chasing your tail for burned out bulbs.

Check the sockets with a test lamp or volt-meter on BOTH contact points to be sure power is getting to the sockets for the tail lamps.

Side marker lights are very often not lit up because the socket itself is buggered. Or half-way buggered.
They are just plastic on most of them, with a tendency to become finicky. Sometimes it's as simple as the bulb burning out, sometimes it's inconsistent and when you hit them the light comes on. On every one of my old Fords (and many others that I've come in contact with) the side marker lights don't work at first. Sometimes a quick slap with the hand will get them to come on for weeks, or even months. Sometimes it takes reaching up behind and jiggling the socket. Then again, as often as not, the bulb just needs to be replaced.

What year is your truck? Are you sure you have sidemarker lights and not just reflectors? Not being snide, just being thorough. Lots of people don't know how their old vehicles work in every detail.

Good luck. If checking out the rear end stuff doesn't work, we'll work our way back, up under the dash. But for now, save your back and neck and work outside!

Paul

 

I don't have side markers. Only reflectors. It's a 69. I have changed bulbs in both tail lights and wiggled around wires at the sockets with no change. Hoping to get time to mess with it tonight or tomorrow after work.

 

There is a plug in the Left Rear corner, 4 wires, that run EVERYTHING in the back.
One is R turn/brake (you know this works)
One is L turn/brake (you know this works)
One is Reverse lights (??)
One is parking lights/license plate (Not working right now)

Unplug and confirm you get power there for each function> If not, then you need to investigate up front. It could be the headlight switch itself? Since it turns the front parking lights OFF with headlights, that means the rear parking lights are on their own contacts. Thus it could be faulty and not turning them on at all?