Troubleshooting lighting system

banjoQ

banjoQ

Senior Member
I am hoping that I can get a few pointers on wiring for my 36' pickup. I have been working on this truck for the past seven months. We are now running strong, stopping as it should. I am having a problem getting the lighting system to function. As of now I have checked the grounds, the bulb and socket. Put in a new brake light sender switch on the master cylinder. It has become obvious to me that this is the weak point to this truck. It was assembled from several different trucks back in 50', and cobbled in a few places. If I could just get the brake lights to work I would be satisfied. I really don't think I will ever drive it at night. If anyone has a couple of tests I could do I would appreciate it. for now, we use good old hand signals. Thnx in advance.
 
Banjo,
Electrical can be hard to troubleshoot, but does your power come from light switch to brake light switch? I would confirm I have power at the brake switch with a test light or volt meter, then check to see if power is sent to other side of switch when pedal is depressed. This might require an assistant. Depending on what this reveals will determine next steps. Is this 6or12 volt?
 
Fred- The truck runs on a 6V system. I have a VOM and can check for current at the brake sender switch. Where the power comes from, I am not so sure. This truck does not have the original light switch. It's got steering gear out of a forties vehicle. I suspect that they wired the high beam switch on the floor as an on/off for the lights. There is no other switch to operate the lights. Again, this truck was put together as a work truck from bits scrounged at the wreckers. I have had to do a bit of detective work just to get to this point. The guys that built this truck are gone. We'll get it.
 
Typically the light will get it's ground via the frame which can be problematic. I ran ground wires to most everything on my 38. Power should come through the switch, so if you have power there you can narrow down the potential problem spot by tracing wire back to light and check for power there when pedal is depressed using meter with ground to frame. You're lucky to get the truck, hope you figure it out.
Fred
 
It appears the truck has a master cylinder and you installed a new stop light switch on the master cylinder. To one of the switch terminals is a hot wire, the other terminal gets a wire that goes back to the stop light element of the tail light bulb. When the brake pedal is depressed the brake fluid pressure makes the switch close and the "hot" will continue to the stop light element of the tail light bulb. The stop light element gets it's ground from the chassis.
To get into any more detail, would need to know battery polarity (+ to ground or - to ground??) two tail lights?, do you have a horn button? The original light switch was mounted at the bottom of the steering box and the switch would actuate both the driving and country beam. The light switch was around the horn button. The original brake light switch was mechanical and mounted very near the brake pedal on the bracket that mounts both the brake and clutch pedals.
 
Terry- Yes, the truck has been fitted with hydraulic brakes. One of the reasons I am having some difficulty figuring this out is the fact the truck was put together with parts from different years. There is no horn button or light switch on the steering wheel. Although the truck runs and drives, I have yet to get the lights to work. Not even sure how they were wired up. Seeing as there is no light switch on the wheel or in the dash, beginning to think the later model high/low floor switch might be wired as an on/off. I do know that it had a working set of lights back in the fifties. Today I will spend some time with it searching for current. I am thinking I can rig a jumper to the switch and see if I can get the tail light lit. Thanks for the input.
 
We chased a brake light problem on our '50 shoebox (6 volt/pos ground) to no avail and finally decided to mount a fuse board and take power from the hot side of the battery to it. We then took a new wire to the master cylinder switch and ran new wiring back to the stop lights. No more brake light problems, but you cannot wire turn signals, which we do not have, with this simple approach.
 
AV8- I spent a hour or so today trying to sort out the wiring and was beginning to think I could create a new circuit just for the brake light. Came down after dinner and read your post. Now I know what I am going to do. I don't even need headlights. Don't think I will ever have it out at night. Turn signals? Not as long as I have an arm to stick out the window. Thanks. I now know I am on the right track
 
What I've found working on electrical is start from the source and see what you DO have...a volt meter and test light can help with this..Also a wire frame the battery to act a a power source helps too...Just work yourself through the whole system...I'm not saying its simple ...But it is just a process of elimination....I bought a used Motorhome and I'm amazed at the things that I got operating just because of a little corrosion or loose wire or bad ground..Good luck with your project...Nice Little Truck....Carl
 
Just install a after market light switch and run new wires. Its the easiest fix you can do.
Power to switch from fuse panel to hot side. One wire from switch to center of dimmer switch and a high and low beam wire to each head light. Most of the dimmer switches are 3 terminal center power from light switch and the two terminals on either side go to high and low beam. From the light switch run a wire to the tail lights. It doesn't sound like it will be a restoration so after market is way to go. I hope this helps!!!
 
I hope you decide to get your headlights working as well, even though you don't plan on driving at night. Once you get this thing going, you're going to have so much fun driving it, eventually you'll end up away from home, and the sun will go down and you'll wish you could see to drive home! Enjoy! :)
 
I agree with Louver Lou and Klicker. It's easier and simpler to just do it all new. I would wire up the head/tail lights. Sometimes it's good to use them even in daylight.
 
Thanks to everyone who weighed in on this problem. I have been working with a VOM, checking for current from the firewall back. Creating a new circuit is the answer for this truck. Should have it done soon. This truck sat for fifty years in a shed in S.F. The fact that it now runs great is truly amazing to me. The way it was put together is an example of how our fathers did things in their time. This one was born out of a wrecking yard in the early fifties. it was worked hard during the week and run up to the country to Deer hunt on the weekend. You cannot drive these things and not think of those who went before you.
 

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The nice thing about "new" electrics is that you can put electrical problems way south on your check list. Worth the bucks and problems.
 
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