- Thread starter
- #21
Ground PIn -> (-) = 3.1
Positive PIn -> (-) = OL (tried high and low beam pins, same result)
Block -> (-) = 1.1
Lights turn off when engine is running??? (6 Viewers)
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Positive PIn -> (-) = OL (tried high and low beam pins, same result)
Block -> (-) = 1.1
3ohms is not continuity.
That is more like a cold light bulb filament.
Were the headlights not connected? You would expect to see the resistance of the filaments rather than overload. Even so, you should see the resistance of the high beam indicator light on the dash.
Maybe add a couple of photos to give a flavour of what you have?
Block is more like it but still not good. You have the earth strap fitted from the battery?
- Thread starter
- #23
Oh my bad. I disconnected the bulbs, trying to remove variables.
Corrected values:
Ground PIn -> (-) = 0.00
Positive PIn -> (-) = 0.5 (tried high and low beam pins, same result)
Block -> (-) = 1.1
(Thank you for your help, btw.. I owe you a coffee!)
And if you remove one headlight bulb then those values double?
I assume you're on a 200 ohm range or something like that. 1k maybe
I assume you're on a 200 ohm range or something like that. 1k maybe
- Thread starter
- #25
Yes, Positive PIn -> (-) doubles. Ground Pin -> (-) stays at 00.00
So if you set the meter back to measure volts, and put the black probe on the battery -ve and the red probe on the headlight connector ground pin, you measure zero volts.
You turn on the ignition and it increases to 12v?
Do you have a "ring tag" grounding wire on your harness - maybe with a few ground wires going to it, bolted to the body somewhere?
Maybe under the fuse box for example?
You turn on the ignition and it increases to 12v?
Do you have a "ring tag" grounding wire on your harness - maybe with a few ground wires going to it, bolted to the body somewhere?
Maybe under the fuse box for example?
- Thread starter
- #27
With the engine off it measures .36v and with the engine on it’s 0.0v. I’ll look for a ring but I havent seen one
How come you read 12V at it earlier then?
- Thread starter
- #29
That is with the engine off testing from the battery negative to the powered headlight connector, with the lights turned on.
I just tested that again to verify.
The same test with the engine running gives me 0 V
fjwagon
SILVER Star
Sounds like you may a bad connection, sometimes reseating a connector may fix it. Or it could have broken strands on a wire except only one strand still attached at connector, giving you a false sense of a good connection. You could also have a bad solder joint in your wire harness. Basically it will pass a continuity test but as soon as you put a load it dies because it(wire/connector)cannot handle the current(load) t run the headlights. The ohms readings you are getting makes think the above. Also don't think you have short. Just got find it. Anyhow, this would be my first guess.
Yea bad connection somewhere.
Possibly a poorly crimped connection.
Sounds like your lights should be working now though if you have 12v on one side and 0v on the other then all good.
As I said, some pictures always help give an idea of what we're taking about. Maybe try that otherwise.
Possibly a poorly crimped connection.
Sounds like your lights should be working now though if you have 12v on one side and 0v on the other then all good.
As I said, some pictures always help give an idea of what we're taking about. Maybe try that otherwise.
- Thread starter
- #32
Yeah, could be. This has been an issue since I got the truck, so I've replaced the ignition switch, and all wires from that ignition switch plug to the headlights, as well as replaced headlight plugs. All solder joints were using the solder melt heat shrink tubs, with twisted wires inside. None of those changes did anything.
I also just removed, disassembled and cleaned the headlight switch.. It turns smoother now, but no change in behavior.
There aren't many other joints on that circuit, but I guess I'll need to start looking from the ignition switch backwards toward the fuseblock.
Thanks for the help everyone, I'm really grateful!
I also just removed, disassembled and cleaned the headlight switch.. It turns smoother now, but no change in behavior.
There aren't many other joints on that circuit, but I guess I'll need to start looking from the ignition switch backwards toward the fuseblock.
Thanks for the help everyone, I'm really grateful!
You previously had an issue where you measured 10v on the ground.
Earlier today you were measuring 12v on the headlight ground.
You also had issues with blowing the engine fuse when starting.
It sounds like you have a simple but fairly fundamental issue causing all of these problems and that sounds like an intermittent short circuit between a positive wire and ground, and possibly a poor connection between battery ground and chassis.
Id start by following the positive feed under the dash that leads to the regulator - lots of places that can chafe through under there with all the metal tags.
Then I'd double check the heavy ground cable between the engine and battery and chassis - remove and clean.
Earlier today you were measuring 12v on the headlight ground.
You also had issues with blowing the engine fuse when starting.
It sounds like you have a simple but fairly fundamental issue causing all of these problems and that sounds like an intermittent short circuit between a positive wire and ground, and possibly a poor connection between battery ground and chassis.
Id start by following the positive feed under the dash that leads to the regulator - lots of places that can chafe through under there with all the metal tags.
Then I'd double check the heavy ground cable between the engine and battery and chassis - remove and clean.
Got a good ground strap from the starter to the fame? Those tend to disappear over the years.
Besides that and the "battery-frame" ground wire, I’ve added a third ground wire "battery-alternator bracket" where the alternator bracket meets the engine block on Coolerman’s recommendation. Alternator ground issues can do wonky things.
Besides that and the "battery-frame" ground wire, I’ve added a third ground wire "battery-alternator bracket" where the alternator bracket meets the engine block on Coolerman’s recommendation. Alternator ground issues can do wonky things.
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fjwagon
SILVER Star
I think at this point if you have not already done it is ohm out the wires from the headlight switch to the connector at the headlight. I don't have a schematic and I don't assume they are a straight shot. Just pick one wire follow it until confirm it's a solid connection and move on to the next. Pull the wire harness partially out so you can start checking it. I would not ping it. Something else you can try while you are thereis wiggle the harness and see if you can the headlights to come on while you have the switch in the on position. There definitely soldered joints in the harness. You may need to get some harness tape for lack if a better word.
- Thread starter
- #36
I'll try this, although I have replaced all of the wiring from the headlights to the connector under the dash (that connects the ignition/headlight switch etc)
I also went back and cleaned/tightened the ground straps at the battery, alt., starter. All fairly new and solid.
I don't have a strap from the block directly to the frame, which seems like it'd be a good idea, but I'm not sure where to attach on the block. I don't want to go unscrewing things just to add a wire. Any suggestions of a location on the block?
There should be a ground wire that goes from a starter bolt to the frame. Since that bolt goes into the block, that is your “block to frame” ground wire. It functions well in that role assuming the connections are clean. No need I’ve heard of to reinvent that wheel.
The problem a few people run into is the alternator grounds thru its bracket to the block (then thru the starter to frame ground). That worked great from the factory, but over the years it can get a bit krusty between the alternator bracket and the block. It can cause some issues with the alternator if that happens. Not super common, but not unheard of either. The solution to that is to clean up the alternator bracket and block connection. Probably overkill, but I run a battery negative wire to the alternator bracket thru one of the bolts that go into the engine block. That creates a circular grounding loop (battery-frame, frame-block, block/alt bracket-battery). You can lose any ground wire and suffer no ill effects, plus it reinforces a good alternator ground. I got the suggestion from Coolerman…
The problem a few people run into is the alternator grounds thru its bracket to the block (then thru the starter to frame ground). That worked great from the factory, but over the years it can get a bit krusty between the alternator bracket and the block. It can cause some issues with the alternator if that happens. Not super common, but not unheard of either. The solution to that is to clean up the alternator bracket and block connection. Probably overkill, but I run a battery negative wire to the alternator bracket thru one of the bolts that go into the engine block. That creates a circular grounding loop (battery-frame, frame-block, block/alt bracket-battery). You can lose any ground wire and suffer no ill effects, plus it reinforces a good alternator ground. I got the suggestion from Coolerman…
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fjwagon
SILVER Star
You can sometimes tell you have a bad groundswhen you instrument cluster lamps are dim. But if you swapped them out to LED's, that idea goes out the window. None of 40's had a ground from the frame to starter. However, a lot of fj60's have them from the factory. I installed them and it does help. But I have to clean ( wire bruch) the oxidation off on the one coming from the battery to the frame everyone once in while. I use dielectric grease and that helps too. I think should be good on your grounds. Those problems are hardest to find.
I do not believe that is a correct statement. See P/N 90980-07003. Labeled as 82001 below.
fjwagon
SILVER Star
I currently have a cold joint in the wire harness on the 45 diesel. It would not start so I trouble shot every component and cleaned/ reseated connectors, did a visual check looking for the obvious and found nothing. The wire harness had never been tampered with so basically that was all that was left to look at. I proceeded to disconnect everything under the hood and snaked it out into the cab. I did the same in cab. So at end everything was disconnected and I went ahead and peeled back the harness and found a cold solder joint. It does happened. This may not be your fix, just be patient and it's broke you will find it. You have to think outside the box my friend.
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