Hey guys, I've been trying to figure out why my headlights don't work for quite some time now. There is no high beam,no lo beam or day time running lights, dimmer switch does not work either. I've checked all the lights, fuses and relays, my parts truck's headlight work fine so I test everything in there. I have taken apart the steering column to test the switches, checked all fuses and pretty sure I have checked all the grounds..The one under dash on left side of vehicle, and the one on both sides of front inner fenders. I checked all the relays I could find, the obvious one under the hood for the dimmer and headlight, and founds one under the dash/steering wheel, and behind the glove box, they were all fine. Unsure If there's another one I'm missing.. Id assume there's only one for the headlights and one for dimmer.. I have the circuit box with the fuses and relays under the hood flipped over to expose the wiring and found when I poked the thin red and green wire with my test light, (clipped to the negative terminal on battery) the one that leads into the headlights relay the lights will go on. I have taken apart most of the panneling so I could inspect the wires and gain access to all fuses and relay. Still no luck... I'm out of ideas... Any help would be greatly appreciated.. Thanks

Just realized there's a seperate thread for electrical issues, sorry about that..

 

Have you tryed replacing the head light switch ?, they can and do go bad.

 

the switch on the steering column? I swapped it with a good working one from parts truck and it didn't solve the issue.. The signal lights work, but nothing else on the switch

 

[QUOTE=dillbike;51095615]found when I poked the thin red and green wire with my test light, (clipped to the negative terminal on battery) the one that leads into the headlights relay the lights will go on. QUOTE]

I'd be suspicous of a poor ground somewhere, because from your description you grounded the relay directly and your lights came on.

I'm guessing that you have a Canadian truck since you mention DRL and 1990.

If so, based on the wiring diagram, you may have grounded the coil for the dimmer relay, which interconnects to the primary headlight relay (22RE motor).

all of the above is pretty speculative. What you need to do is look at the schematic for your headlights. Have you looked at those? There are some links in the sticky notes at the top of the forum.

 

I'm having the EXACT same issue on my '91 4Runner.

I swapped the Headlight relay out with a known good one, no good, also hooked my relay up to the battery and it energized and closed, so not a relay problem.

Swapped out my combo switch with a know good one...no good.

When I take a little jumper wire, and jump out the large contacts of the HL relay socket, my lights and high beams work fine. Which is how I have been driving at night for 2 months now, with a jumper wire in the relay socket.

So something is causing a bad ground from the HL switch to the relay and not letting the relay energize. The relay has a constant 12V on one side of it, when you turn your switch on, you provide the ground to the relay (and the headlight circuit), so it will energize and close the contacts, passing 12V through the other side of it to the headlights.

I cannot for the life of me figure out why or where I have a bad ground to my HL relay.

When I measure the relay socket with a meter with my HL switch turned on, I get a good ground, and battery voltage at the realy socket. I get almost 13V to it, so how can that not energize the relay????

Also the flash function of the high beams must us the same ground to energize the HL relay, because the flash function doesn't work either, with either switch.

 

I agree it does not make much sense.

I've found that voltmeter readings can sometimes be a bit misleading as the voltmeter draws no real power. I've seen dead batteries still give "good" voltage. Does a test light across the same junction you tested light up? If it lights up weak you might still have a poor ground. You'd think that if it lights up a bulb it should have enough current to pull in a relay.

 

You should try a voltage drop test on the relay ground side. An Ohmmeter will give a low resistance reading even if one strand of wire is left, but the voltage drop across that same single strand will reveal a problem. A maximum of .2 volts loss over any wire, switch, fuse, connector, etc is allowable by almost all manufacturers.

Just in case you or somebody reading this doesn't know what I'm talking about, connect one lead of your voltmeter to the relay ground terminal, probably from the underside of the fuse block as you need the relay to be installed, and the other to the battery negative post, or a good body ground. Turn the headlights or whatever you are testing on. If your meter reads less than 0.2 volts then the circuit is good. Above that reading indicates there is unwanted resistance in the circuit. If it reads battery voltage then there is a break in the wire or a bad ground or a bad DRL relay if you have daytime running lights.

The wiring diagram with and without DRL and troubleshooting can be found here.
http://personal.utulsa.edu/~nathan-b.../4lighting.pdf

 

I found this request for help but cannot find the solution. Was there a solution? Is there a solution?Hey guys, I've been trying to figure out why my headlights don't work for quite some time now. There is no high beam,no lo beam or day time running lights, dimmer switch does not work either. I've checked all the lights, fuses and relays, my parts truck's headlight work fine so I test everything in there. I have taken apart the steering column to test the switches, checked all fuses and pretty sure I have checked all the grounds..The one under dash on left side of vehicle, and the one on both sides of front inner fenders. I checked all the relays I could find, the obvious one under the hood for the dimmer and headlight, and founds one under the dash/steering wheel, and behind the glove box, they were all fine. Unsure If there's another one I'm missing.. Id assume there's only one for the headlights and one for dimmer.. I have the circuit box with the fuses and relays under the hood flipped over to expose the wiring and found when I poked the thin red and green wire with my test light, (clipped to the negative terminal on battery) the one that leads into the headlights relay the lights will go on. I have taken apart most of the panneling so I could inspect the wires and gain access to all fuses and relay. Still no luck... I'm out of ideas... Any help would be greatly appreciated.. Thanks

 

Hey guys im new to this site. But here is the problem i swapped cabs and its runs and everything now it didnt befor and now i cant get my headlights to turn on or my running lights. I have LED taillights so i had to get the trailer adapter my turn signals work and so do my break lights but when i hit my breaks my front turn signals turn on as well not sure of what the problems is. I have a 88 toyota pickup carb. If that helps.