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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

Headlight: Troubleshooting

Old 10-11-2017, 12:53 PM
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How Headlight Control Works and Troubleshooting - 22RE and other early models

Voltage test points and expected voltage readings.
To the best of my knowledge, the schematic and tests here apply to USA model (no DRL) 3rd-Gen and earlier 4Runners/Trucks.

(I verified below to apply to 1986 to 1988 22R-Eliable , based my own 1986 and pdf schematic of 1988).
This will determine if your wiring and power are good. If wiring and power are good, suspect your bulbs.
Other tests may be needed but these points will cover most troubleshooting scenarios.

Headlight relay and fuses are in fuse block in the engine compartment.


PERFORM THE CHECK BELOW WITH GOOD BULBS CONNECTED. PROBE THE BACK OF CONNECTOR OR PULL IT OUT JUST ENOUGH SO YOU CAN PROBE THE PIN BETWEEN THE GAP.
Multi-meter in Volts DC mode (usually 20-V range IF not auto-ranging).
Negative (black) probe on bare, shiny metal of negative battery post or bare, shiny metal of body ground.
Probe points A through H in Off, Low-beam, and High-beam modes.
Points E,F,G and H are on the H4 connector. Probe the back of the pins or Pull terminal out slightly (LIKE THIS) to be able to probe the contact blades while lights are still operational.
EXPECT READINGS BELOW FOR NORMALLY-FUNCTIONING LIGHTS. Let us know what you see is different about your system..




H4 CONNECTOR PIN-OUTS (FEMALE SIDE ON HARNESS)
[/INDENT]

ALTERNATIVE METHOD OF VOLTAGE CHECK (across pins of the H4 connector):
NOTE: THIS SHOULD ALSO BE DONE WITH GOOD BULBS CONNECTED, otherwise you would not detect bad combo switch contacts. I ONLY PICTURE UNCONNECTED CONNECTORS TO HELP SHOW PIN-OUTS. I will update with actual, real-world pics when I get the chance.


LOW-BEAM


[/INDENT]
HOW HEADLIGHT SYSTEM WORKS.
(Schematic below)[INDENT]


When headlight switch is turned on, headlight relay in (engine compartment fuse block for first-gens 22RE) energizes, closes contact, sends +12V to both headlight fuses and to pin 3 of both bulbs.

Toyota uses switched-ground control; Dimmer-switch select which filament (high or low) of bulb to connect to ground.
When in low beam position, switch contact 6 (HL) of dimmer-combo switch connects pin1 (red with green stripes) to ground (G = zero volt, H is floating so there is 12Volt there.)

When in high-beam position, switch contact 5(FU) connects pin 2 (red with yellow stripe) of bulbs to ground (H = zero volt, G is floating so there will be 12V there. G is also connected to high-beam indicator so that 12V will turn it on.)

Last edited by RAD4Runner; 01-08-2019 at 06:50 PM.
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Old 10-12-2017, 03:31 PM
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Old 11-01-2017, 08:36 PM
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Thanks, Robb.
I added "how it works" and schematic above. That should cover general troubleshooting.
We will add/discuss details as members describe their specific issues.

Last edited by RAD4Runner; 11-27-2017 at 10:39 AM.
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Old 01-07-2018, 08:35 PM
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High beams do not work, High beam flash works AND low beams work

Symptoms: BOTH high beams do not work, High beam flash works AND low beams work.

Troubleshooting:
Turn headlights on. Make sure low beams come on.
Switch to high beam. Still no light, of course?
Find Pins 5 (Red-Yel Wire) and 13 (wht-blk) of dimmer combo switch . Jump 5 to 13. Got highs?
If you get high beam, it's bad contact between those 2 pins. You may be able to clean or fix. However, the flaw in headlight wiring of that generation where current flows on thin wire over a convoluted path (ask 4crawler) and though the dimmer-combo switch will shorten it's life again.
If you still don't get highs, jump pin 5 directly to shiny, bare metal ground. Got highs? If yes, it's bad connection between pin 13 and ground.

(I have not actually done this work hands-on, so would appreciate if anybody could share pictures of switch and test points/pins.)


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Old 04-16-2018, 04:56 PM
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I have A similar issue on my 1987 SR5 4runner. My low beams work MOST of the time, then, POOF, lights out total darkness. But, I can turn on the high beams and they would work. I can flash the high beams a time or 2, or turn the lights off and on, and then the low beams will work again BUT when the low beams come back on, the high beam indicator stays on in the instrument cluster.
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Old 04-16-2018, 05:00 PM
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Originally Posted by bendiesel76 View Post
I have A similar issue on my 1987 SR5 4runner. My low beams work MOST of the time, then, POOF, lights out total darkness. But, I can turn on the high beams and they would work. I can flash the high beams a time or 2, or turn the lights off and on, and then the low beams will work again BUT when the low beams come back on, the high beam indicator stays on in the instrument cluster.
Perform checks as described in post 4 above, and let us know what you find.
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Old 04-16-2018, 05:34 PM
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RAD4runner, I’ll check that and get back to u, taking my rig to the shop tomorrow to try to fix another issue... If you don’t mind would you check out my thread https://www.yotatech.com/forums/show...3&goto=newpost and see if anything jumps out?

Last edited by bendiesel76; 04-16-2018 at 05:36 PM.
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Old 04-16-2018, 05:37 PM
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Originally Posted by RAD4Runner View Post
Perform checks as described in post 4 above, and let us know what you find.

RAD4runner, Iíll check that and get back to u, taking my rig to the shop tomorrow to try to fix another issue... If you donít mind would you check out my thread https://www.yotatech.com/forums/show...3&goto=newpost and see if anything jumps out?
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Old 04-16-2018, 07:44 PM
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Originally Posted by bendiesel76 View Post
RAD4runner, Iíll check that and get back to u, taking my rig to the shop tomorrow to try to fix another issue... If you donít mind would you check out my thread https://www.yotatech.com/forums/show...3&goto=newpost and see if anything jumps out?
K.
Sorry. Post 4 is actually for when high-beam does NOT work but low-beams do.
Better to do first post checks. You can do them AT THE HEADLIGHT CONNECTOR ITSELF. https://www.yotatech.com/forums/f116.../#post52379293
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Old 04-16-2018, 08:14 PM
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High beam works, High beam flash works but LOW-BEAM DOES NOT WORK

Originally Posted by bendiesel76 View Post
I have A similar issue on my 1987 SR5 4runner. My low beams work MOST of the time, then, POOF, lights out total darkness. ... the low beams will work again BUT when the low beams come back on, the high beam indicator stays on...
Most likely high resistance in the low-beam contacts of dimmer combo switch.

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Old 04-17-2018, 06:15 AM
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Originally Posted by RAD4Runner View Post
Most likely high resistance in the low-beam contacts of dimmer combo switch.

thanks man. I really appreciate the info!
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Old 05-12-2018, 08:57 PM
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I just got through looking into this problem today. I actually have two headlight/blinker switches. I bought the one I'm using now years ago when the original one started having the high beam black out problem. Well the replacement started doing the same thing.

I broke both switches down. The original switch was just full of old grease. Removing the headlight toggle, the spring, and ball, and cleaning everything with electronics cleaner has everything working again after lubing with dielectric grease.

The second switch had a solder joint turn lose on there Y/R wire on the bottom of the headlight switch.

What I want to know is, what's the best way to clean rusty male pins in the PIN connector besides a tiny flathead screwdriver?

Last edited by Tims86Toy; 05-12-2018 at 08:59 PM.
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Old 05-13-2018, 07:21 AM
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Itís been while, but hereís what I have..... I tested the working at the headlights.... drivers side NOTHING on low beam but high works fine....passenger side, BOTH work correctly..... however now, I have absolutely zero low beam... I have to run my dogs or high bans all the time ...
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Old 05-13-2018, 10:36 AM
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Originally Posted by Tims86Toy View Post
...What I want to know is, what's the best way to clean rusty male pins in the PIN connector besides a tiny flathead screwdriver?
Good job!
Look closely at connector housing. There is a little tab you can push out of the way with a tiny jeweler's screw driver, then you can pull the pin out from behind. Clean with very fine sandpaper or steel wool.
OR fold very fine sandpaper over the tip of your tiny flathead screwdriver.

Now that you have fixed the switch. Help extend its life, and get brighter lights with H4 conversion harness. Google "convoluted path 4crawler".
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Old 05-13-2018, 10:37 AM
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Originally Posted by bendiesel76 View Post
... drivers side NOTHING on low beam but high works fine....passenger side, BOTH work correctly..... however now, I have absolutely zero low beam... ...
REPEAT: EXPECT READINGS BELOW ABOVE ARE FOR NORMALLY-FUNCTIONING LIGHTS. Let us know what you see is different about your system..

Nothing what? What voltage readings did you get? Where?
A picture paints a thousand words.

Last edited by RAD4Runner; 05-13-2018 at 10:41 AM.
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Old 05-13-2018, 05:05 PM
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Originally Posted by RAD4Runner View Post
REPEAT: EXPECT READINGS BELOW ABOVE ARE FOR NORMALLY-FUNCTIONING LIGHTS. Let us know what you see is different about your system..

Nothing what? What voltage readings did you get? Where?
A picture paints a thousand words.

didnt take a pic, but , I was getting 11.8v DC on the high beam for the drivers side and no reading at all on the low beam. On the passenger side I was getting 12.2v DC on the high beam and 11.8v dc on the low beam. These were taken at the plug the hooks to the headlight. But, like I said, now I have no low beam, Iím just running highs and/or my 6Ē KCs.
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Old 05-13-2018, 05:10 PM
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I had a lot of small things,to work on, I’ll jump the red/green wire to ground and see if that gives me any positive results. If nothing else, I’ll run another set of wires and add a rocker switch for the low beams.
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Old 05-26-2018, 11:25 AM
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Originally Posted by RAD4Runner View Post
Good job!
Look closely at connector housing. There is a little tab you can push out of the way with a tiny jeweler's screw driver, then you can pull the pin out from behind. Clean with very fine sandpaper or steel wool.
OR fold very fine sandpaper over the tip of your tiny flathead screwdriver.

Now that you have fixed the switch. Help extend its life, and get brighter lights with H4 conversion harness. Google "convoluted path 4crawler".
Nice! Thanks for the tip! But I gotta go back and solve the riddle of a ground problem in my gauge cluster first. I thought I fixed it but I still have no temp or fuel gauge.
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Old 05-26-2018, 06:18 PM
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Originally Posted by Tims86Toy View Post
...ground problem in my gauge cluster...
You absolutely, positively sure it's a ground problem? "Bad ground" is most people's panacea - LOL!
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Old 06-11-2018, 02:04 PM
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Oh Great and All Knowing Master Guru of all things magical and electric.

So I was about to take the voltage measurements on my lights as they are, before doing the relay thing. I removed the driver’s side 3 prong headlight connector and found that the connector was looking pretty sad (at least very dirty if not semi melted or burnt. So I figured I would replace the connector vs. screwing around trying to get it clean.

Then IIRC part of the relay deal is up sizing one of the wires. I see it on a diagram you made but have no darn clue which wire that is. Is it one of the wires that comes out of the 3 prong headlight connector?

Last edited by L5wolvesf; 06-11-2018 at 02:06 PM.
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