Chasing Down Electical Issues? (1 Viewer)

[TEXASgirl]

I have zero experince tracking down electrical problems. My headlights and blinkers do not work currently. I'm looking for recomendations on how/where to start and what equipment is recomended. Do I start at the headlights and work backwards or.....? Please keep in mind that outside of hooking up a battery and a few odds and ends I am a complete novice.

Thanks!!

 

[FJforty]

Find a post or a tutorial on how to use a multimeter or volt/ohm meter. You can buy one these days for a few dollars. Then you can test stuff, measure voltages and learn a little. The basics are easy with a meter.
Oh! Check your fuses.

 

[tequila4x4]

do a search on electrical diagram for your truck, then follow the wiring. it takes time, but the fj40 wiring is not hard to do. a tester will help

 

[Makinhole]

What has changed since they last worked? A test light is also an easy way to see where the system has current. Good luck.

 

[Pin_Head]

The headlights and turn signals are on separate fused circuits. If everything else works, I would start by checking the fuses and cleaning the fuse block. Disconnect the battery first before you wire brush the fuse block.

 

[TEXASgirl]

Thanks for the feedback. Keep it coming please.

The challenges:

Lights and blinkers have not worked since I purchased the vehicle so, unfortunatley I dont have a "they worked before I did this" situation to compare to.

It has a V8 conversion and some obvious rewiring under the hood so I don't think I'l be able to follow a standard Landcruiser Wiring diagram

Custom glove box door with lock and no key . LOL. I am assuming the fuse block is in there....is that correct?

 

[SD_rdcruzer]

Fuse block "should be" just forward of the drivers door below the dash. With the V8 conversion, who knows.
That's where I would start.

 

[GarageRat]

Check stock location first for a fuse block (under dash, above the kick vent IIRC) and see if the fuses are blown just to make sure it's not an easy fix. If you have to rewire that section I would rerun a wire from the switch to the lights at a minimum using good sized wiring (I used 12 gauge), possibly rewire that entire circuit depending on the PO. The blinkers may not be grounding, hacked wiring, or just a turnsignal switch with nothing connected to it.

Luckily for you these vehicles are relatively simple to wire, I just did a ground up rewire using a Northwestern block on my '63 in a couple days using MUD to figure out terminals on the factory switches. Not very tough, just have to make sure you think your routing through so that you don't become the dreaded PO. I would definitely invest in a good multimeter tool as they can be invaluable when wiring which you may have quite a bit of in the future.

As for the glovebox, locksmith or drill the lock out. Good Luck!

 

[Rambrush]

As posted locate the fuse block. Using a test light check each side of each fuse for power coming and going. If all is well locate the light switch is there power there? If not track it back towards the fuse block to see where it got lost.
If there is power heading out of the light switch then you can make a quick check and verify by unplugging the headlights and checking for power. Maybe you have blown bulbs? If no power at the headlight socket but power at the switch you now know there is a problem between the two points.
This will be time intensive but tracking it down is the only way.
Write down what color wire is on the headlight switch include the tracer color if it has one and that will help during the process to locate the right fuse. If you have the battery disconnected you could utilize a toner/Ohm meter to track wires but we won't go there as that is not a common practice first step idea.

 

[edwjmcgrath]

On this vehicle, almost everything is wired with just one wire (power). They count on screws and metal-metal contact to provide the ground return. Ground problems are right up there with fuses and corrosion as the cause of electrical issues.

To eliminate that as a cause, I always start by running a jumper cable from the negative terminal of the battery and connecting my test probe ground to it. That way, if there is power on the single wire, the light will illuminate. If the light illuminates and the fixture (headlight/taillight) doesn't, you've probably got a ground problem.

 

[Copenhagen1]

..... I would start by checking the fuses and cleaning the fuse block.

Best advice I ever got on MUD was to clean my fuse block. IF yours is still in the stock location and is still a stock fuse block, disconnect the battery, take out a couple bolts, unhook harness from back and take out fuses. Then I took a small round file and filed the fuse holders back to a shiny brass so that I knew there was good contact. You can do this with emory cloth or sand paper at every connection to make sure that it is not 30 years of corrosion keeping life out of your headlights.

 

[Rambrush]

The trick here what was rewired? Did they go away from stock? That will be the question today.

On this vehicle, almost everything is wired with just one wire (power). They count on screws and metal-metal contact to provide the ground return. Ground problems are right up there with fuses and corrosion as the cause of electrical issues.

To eliminate that as a cause, I always start by running a jumper cable from the negative terminal of the battery and connecting my test probe ground to it. That way, if there is power on the single wire, the light will illuminate. If the light illuminates and the fixture (headlight/taillight) doesn't, you've probably got a ground problem.

 

[Pin_Head]

Chances are the headlight and turn signal wiring is still stock, even with a V8 conversion. No need to change them.

Start with the headlight circuit first, since it is simpler. It is just the fuse, the on/off switch, the hi/lo beam switch and the lamps. Turn the switch on and use your volt meter to measure the votage between the wire and ground at the lamp. It is probably close to 0V, since they don't work. Follow the wire back to the dimmer switch and check again. Then check the on/off switch and the fuse block. Look for where you see 12V on the wire. When you find it, the part that the wire is attached to is probably bad.

 

[Unoman]

Are they grounded properly and are the grounds clean?

 

[Deni]

OMG you guys "Please keep in mind that outside of hooking up a battery and a few odds and ends I am a complete novice. " You are asking things that may not be known... like what was rewired. Someone go help out!! I am in SC and can't and if I did it would be like the blind leading the blind.

 

[Dedtruk]

Pin Head is right, but if you don't want to invest in the multimeter, clean everything up (small wire brushes, emery cloth, spray contact cleaner) first. After cleaning, dielectric compound on contacts to keep 'em clean. Sometimes fuses look good but aren't. Try a couple or replace the set with new. Grounds are also a common problem. Clean off rust and other corrosion, sand down to clean metal if necessary, and run a temporary jumper wire/ground just to test the rest of the circuit. Eliminate fuses, fuse block, and grounds as likely culprits and you'll at least have a baseline from which to do more diagnosis as needed. It's cheap, easy, and solves many, perhaps most problems.

 

[Copenhagen1]

OMG you guys "Please keep in mind that outside of hooking up a battery and a few odds and ends I am a complete novice. " You are asking things that may not be known... like what was rewired. Someone go help out!! I am in SC and can't and if I did it would be like the blind leading the blind.

She has a husband that owns a hardcore Bronco. I am sure he can help her with implementing the suggestions found here on Mud. I think she bought a 40 because she wants to learn.

 

[K2KK]

In my '70 I had a fuse in the light switch itself. I didn't realize this until I changed out my headlights for some halogen lights and it kept blowing(to much current going through it). I had to switch it out(pardon the pun) to a lager amp switch.
I would check that too...

 

[FishNinJay]

On this vehicle, almost everything is wired with just one wire (power). They count on screws and metal-metal contact to provide the ground return. Ground problems are right up there with fuses and corrosion as the cause of electrical issues.

To eliminate that as a cause, I always start by running a jumper cable from the negative terminal of the battery and connecting my test probe ground to it. That way, if there is power on the single wire, the light will illuminate. If the light illuminates and the fixture (headlight/taillight) doesn't, you've probably got a ground problem.

Similar issues on my converted '71 rig. Bunch of cut wires, but I think the fusebox and most wiring is probably original. Why would they necessarily change everything just for the conversion? My reverse light and horn does not work, never did. Brake lights don't work, but that might be the mechanical brake light switch in the floor, not the wiring (turn signals all work fine).

RE: jump cable fr neg batt to test probe ground
wow... best lightbulb moment I've had in awhile here on Mud!!

Seriously.. can't believe I didn't think of this before. I've got my 5ft-11in, 230lbs folded and squeezed under my dash testing a bird's nest of cut wires, touching my probe ground to every nearby bolt!

Thanks for the tip..


On a related note.. any tips on figuring out horn circuitry? Never had one working, and aftermarket Grant steering wheel on GM column. Where are the standard locations for the actual horn in the engine bay? horn relay? fuse?
Thx

 

[myfirstlc]

Good luck Texasgirl. Hope it works out. My headlights don't work as well, on a 1970. Does anyone know where the ground to the headlights is located?? I have traced all the wires and can't seem to locate it.