Tail light issues (electricity problems?) (1 Viewer)

[Paraglider]

I've got an HJ47. It was owned by a farmer before and he didn't care what worked as long as the thing ran and could haul and hold equipment, so I've got a few issues to resolve. One is my rear lights. The hazards work, the blinkers work, one brake light works. No lights turn on when I turn on my headlights. So I'm trying to figure out why the other brake light doesn't work and why the tail lights don't go on when I turn on my headlights.

I went under, looked at the connections at the rear, took them apart, and see nothing amiss on the side the brake light works but a red wire has apparently become disconnected on the other (is that the brake light?). Here are some pics.

These are the connections where everything except the tail light part works.

What is the grease about and what are the two metal tips for? They were covered by a piece of tape. I recovered them after putting more grease and cleaning it up.

This is the one with the red wire disconnected. Other wires are brown, black and white on both tail light fixtures. Not sure what the black wire going into that black box is about.

 

[ToyotaDon]

You'd probably be better off posting in the 40/55 section. Someone else may know or have access to the wire color codes, but I'll offer a little advice.

Those appear to be aftermarket lights, possible LED, since there's a resistor/diode box inline. If so, and you want to keep them, spend a little more time cleaning them fully, cut off those bullet connectors, and put everything back together with heat shrink connectors.

If they are LED, there are no bulbs to replace, so the complete assembly might have to be replaced anyway. You'll want to check each wire with a test light or voltmeter before sealing it all up. Remember you need a good ground supply for the lights as well.

My guess about the spot with the grease is that it is a connector for the backup lights. The grease should be dielectric grease to keep water off the terminals and wires to prevent corrosion.

 

[Paraglider]

You'd probably be better off posting in the 40/55 section. Someone else may know or have access to the wire color codes, but I'll offer a little advice.

Those appear to be aftermarket lights, possible LED, since there's a resistor/diode box inline. If so, and you want to keep them, spend a little more time cleaning them fully, cut off those bullet connectors, and put everything back together with heat shrink connectors.

If they are LED, there are no bulbs to replace, so the complete assembly might have to be replaced anyway. You'll want to check each wire with a test light or voltmeter before sealing it all up. Remember you need a good ground supply for the lights as well.

My guess about the spot with the grease is that it is a connector for the backup lights. The grease should be dielectric grease to keep water off the terminals and wires to prevent corrosion.

Thanks for the info. That's helpful. How do you test a ground to know if it's good (I hardly know anything about electricity.) I'll go ahead and post in the 40s section and see if anyone knows those lights specifically. I don't see how there would be any room for light bulbs inside so you're probably right about the LED. On the other hand, I get the impression the PO would have only replaced something if he absolutely had to--but maybe in 34 years . . . .

 

[ToyotaDon]

The best check of a ground is with a voltmeter. The circuit has to be "live" and you connect the meter from the ground side of the light bulb (load) to the negative terminal of the battery. Any voltage measured is your amount of "voltage drop". There should be less than 1 Volt reading on the meter.

If you're not comfortable with a meter, you can do some checks with a test light. Basically, as you check for power at each wire with the switch turned on, you would connect the other end of your test light to the ground wire at the same connector. The light should be bright; any dimness means there is resistance somewhere in the circuit. Using a different ground for your test light would tell you if it's on the ground or power side.

Hope that helps. You might check out these articles as well:
Toyota Trails - May/June 2016 Issue
Toyota Trails - September/October 2016 Issue

 

[Paraglider]

Thanks for the additional info. It looks like I'm going to "have to" learn something about electricity! I've been avoiding it all my life, so I guess I can thank my cruiser for forcing me to get out of my comfort zone. Started reading the two articles and will continue. I also did post it in the 40s section.

I do have one question about what you wrote and that will tell you where I am with regard to electricity knowledge. You say to connect the meter from the "ground side" of the light bulb (same if it's a LED?) to the negative terminal. What does that mean--connect to the ground side? So if I connect to the negative terminal on the battery, it means I have to know where these wires are that go to the tail lights in the vicinity of the battery? Even if I don't understand the answer, I promise not to bug you a third time.

I understood the second part about the test light!

Thanks again.

 

[ToyotaDon]

The light bulb needs 2 wires going to it, or 1 wire going to it, and 1 going away from it. These are your power and ground wires (LEDs have to be connected properly to work, since they only allow current to flow one direction). The power wire to the bulb gets there through the fuse block, switches, etc. while the ground circuit finds its path back to the battery through the chassis & body of the car. Typically we connect our meter or test light to a "good ground" and check for power at the bulb or wires, but this is only half of the equation. We also need to make sure the bulb has a good ground path, so we can check that as I described earlier, connecting the black lead of the meter to the wire (or bulb socket ring) at the light or connector.

I hope that didn't confuse you more.

 

[Paraglider]

The light bulb needs 2 wires going to it, or 1 wire going to it, and 1 going away from it. These are your power and ground wires (LEDs have to be connected properly to work, since they only allow current to flow one direction). The power wire to the bulb gets there through the fuse block, switches, etc. while the ground circuit finds its path back to the battery through the chassis & body of the car. Typically we connect our meter or test light to a "good ground" and check for power at the bulb or wires, but this is only half of the equation. We also need to make sure the bulb has a good ground path, so we can check that as I described earlier, connecting the black lead of the meter to the wire (or bulb socket ring) at the light or connector.

I hope that didn't confuse you more.

Slowly but surely it's coming to me. Now I just need to get a test light or ohm meter to apply the info and see if I really understood. Thanks for the basic lessons on electricity.

 

[N22]

Does it have a tow hitch? Have had bad tow light plugs and converter take out my tail lights.

 

[Paraglider]

Does it have a tow hitch? Have had bad tow light plugs and converter take out my tail lights.

Thanks for responding. I transferred this thread to the 40s and 50s thread forum and just yesterday figured out the problem (the PO had rerouted the green wire--the tail light wire--to another place that was not even connected to anything). Once I disconnected those wires and connected green (from fuse) to green (going back to tail lights), it all worked. Now I'm working on why the speedometer and odometer and oil pressure and amp gauges don't work. Took it out of the dash just a couple hours ago and looked, cleaned, lubed but haven't had a chance to start her up to see if any difference. At least now I know how to replace the instrument cluster if it comes to that.

 

[N22]

Glad you got the lights working. Wasn't sure if you'd figured it out yet, so just thought I'd mention it.

 

[Paraglider]

Glad you got the lights working. Wasn't sure if you'd figured it out yet, so just thought I'd mention it.

The PO was the "wire whatever wherever" king so I'm kind of in the process now of going thru and eliminating all wiring that isn't connected to something (and there's a lot of it), so wouldn't surprise me if the tow wiring doesn't work or is messed up somehow. (Wish I could talk to the PO and ask him what he was doing but unfortunately, I bought my truck thru and intermediary who doesn't seem to want to cooperate and give me the contact info.)