Simple question:
Why is my right headlight so much brighter than the left? The right is even a different color “white” compared to “yellow” for the left.
As I’ve stated before Electrical is my weakest skill when it comes right down to it I SUCK!
Bulbs are same brand (Wagner) sealed beams of the same age.
Working from page 58 of (Toyota Electrical Wiring Diagram 4Runner 1989 Model) that came with my FSM.
Multimeter tells me 12.23v on pin #3 from relay on both sides .
Here’s where I get lost, Without bulbs installed pin #1 R-G wire common to both, on RH side has 12.34v, LH side has 12.26v at the same time pin #2 R-Y wire common to both, shows –42 RH side and –23 LH side.
With both bulbs installed and lights on, pin #2 shows 10.92v RH side and 10.82v LH side. Both wires #1 and #2 show .7 K ohms resistance between connectors.
Simple Answer?

 

Sometimes when a head light bulb is going bad internally it will start getting dimmer until it finally goes out. Try swapping headlights (or by a new one) and see if that makes a difference.

 

If you are convinced that you have a wiring or connection problem....What you haven't checked is the right and left fuses for the headlights. It's possible that the connection on one might not be as tight as the other or one might be corroded and the other not, or one fuse element might have a higher resistance value than the other fuse element. Any of these will increase the resistance of the circuit. Increase the resistance, you lower the amperage, lower the amperage and you lower the power(watts) available in the circuit.

On the other hand it might just be the lights! The last sealed beams that I bought for my truck were GE halogen (can't remember the exact model), but they were the most expensive model that GE made. I put them in my truck, one was a bright white light similiar to a mercury vapor street light, the other was a yellowish light similiar to a high pressure sodium street light. They were the exact same model, were on the shelf together, so I assume they were from the same manufacturer's lot.
The luck of the draw I guess!

By the way what were you reading when you measured -42 and -23???? A negative sign I can see if you have the polarity of your meter leads reversed, you are after all dealing with a DC circuit. "+" and "-" , but the rest of it does not make sense to me!

 

Run a new ground to the dim light and see if that helps.

 

Head light are cheap, just buy a new one. My bet, it's fixing to go out anyways.

 

switch to the Hella H4 lenses and put in some HIDS

no more dim lights

 

Won't help as the Toyota headlights are switched ground. That is the ground for the headlights is back at the dimmer switch on the steering column.

What you could do is test the voltage at each light (while on) and see if there is a wiring issue:
- http://www.4crawler.com/4x4/CheapTri...ml#VoltageTest

 

Couldn't you jumper a ground at the headlight just to see if its the light or wiring? If the light has direct power and ground and is still dim its the light. If not its the wiring. I'm no electrical master by any means but it is usually best to start witht the simple stuff.

 

I suppose you could try that, but there are two wires to the headlight, the common power feed and the pair of H/L ground wires:



So a ground jumper would tell you if you had a poor connection back to the dimmer switch, but not if you had a bad power connection. A volt meter test would tell you if there is an issue and by testing the battery-common and ground to H or L pin voltage drops on the headlight connector you can isolate the problem to one of the other connection.

Might also try pulling and checking the L and R headlight fuses, might be one is partly melted or there might be corrosion in the fuse holder sockets.

 

do this and most problems solved. Also keeps low beams on with high beams which is a plus.

 

I had the same problem on my '94. After countless days of testing with a meter all over the lighting circuits, I happened by an old junkyard on the outskirts of town. The guy behind the counter asked my as I walked by why I didn't hook the engine ground back up on my truck? I went out and looked, and low and behold he was right. I hooked it back up, and all my gremlins were gone.

I still feel bad about this one, as I have been an electronics technician for over 15 years and didn't catch it ....

Bob