hey guys i bought a 93 toyota 4x4 pu. the headlights wont work when you turn them on. but if you hold the lever back with your hand the brights work. i checked all of the grounds and the relays are good. i tested the plug that goes to the headlight itself and all three terminals have power. we tested my buddies toyota and only two out of the three terminals have power. do you think its the main switch thats causing this to happen?

 

Do you mean that all three wires are hot all the time.

One is low beam the other high beam and the odd wire is your ground

if you have power to your ground wire it is a wonder the fuses have not blown have you checked both sides ??

Check at the connector that comes from the headlight switch that should tell you.If you have a bad switch

 

See below:
- http://www.4crawler.com/4x4/CheapTri...eadlight_Combo

And realize the Toyota headlights are wired in switched ground mode:
- http://www.4crawler.com/4x4/CheapTri...l#HarnessTypes



And typically you do see 12 volts at 2 wires (w/ the headlights on) and the one not at 12 volts is grounded to turn that filament on. If you see 12 volts on all 3 wires, then you have no ground connection. Ground is via the combo (dimmer) switch on the steering column. The common pin have 12 volts all the time, then either the low or high beam terminal is grounded to turn that side of the light on.



Also, if a filament is blown on a given bulb, you'll typically not measure 12 volts on that pin.

 

Are you sure both low beams are not blown?

 

do you have sealed beams?

in my 85 both low beams are blown, but the high beams work

 

ya all three wires are hot all the time. i havent checked the passenger side wiring harness only the drivers side.

when you say the connector that come from the headlight switch, do you mean the harness in the steering column?

 

that first link you put sounds like the problem i'm having. i'll try that and see if it'll do the trick! thanks