Headlights, no brights

[superfunk]

Hey,

Just finishing up my final little things to get this car on the road. I was checking my lights and determined that my brights werent working properly. My driver side light it burnt out. The passenger side will light up, but will not switch to brights. When I hit the switch, the light get slightly brighter, but it is just as if more current is going to the bulb and its not switching bulb circuits like it should.

Anyone have ideas how to fix this. I have the electrical diagram from chilton but its pretty much useless. I konw that on old VW vans goofy things would happen if you had a burnt lightbulb. Will this fix when we replace the lightbulb, or do I have to dig through the wiring to fix this.

Thanks,

Adam

[SteveJ]

Hey,

Just finishing up my final little things to get this car on the road. I was checking my lights and determined that my brights werent working properly. My driver side light it burnt out. The passenger side will light up, but will not switch to brights. When I hit the switch, the light get slightly brighter, but it is just as if more current is going to the bulb and its not switching bulb circuits like it should.

Anyone have ideas how to fix this. I have the electrical diagram from chilton but its pretty much useless. I konw that on old VW vans goofy things would happen if you had a burnt lightbulb. Will this fix when we replace the lightbulb, or do I have to dig through the wiring to fix this.

Thanks,

Adam

What year Z do you have? All of the S30s have basically the same circuit for their headlights, so if you have an S30, the diagram in the Chiltons isn't useless. I was able to use it to learn the headlight circuit when I was designing a relay system (since surpassed by the plug-n-play system offered by a member of this site).

Search this website for a simplified diagram of the headlight circuit that I drew. That may help.

1st - If you have a known bad headlight, replace it. Also make sure you have dual filament headlights.

2nd - If it was brighter when you used the switch, the circuit was probably working.

3rd - Check your fuses, or better yet, just replace them. It's cheap.

4th - You can always remove and clean both the headlight and dimmer switches. Be careful dismantling the headlight switch as parts will want to pop out and disappear.

5th - Check the wiring harnesses. You could have a loose plug or corroded connection somewhere.

If you have a ZX, the diagnostics differ slightly, but I don't know the details.

[Zs-ondabrain]

Both headlights have a fuse in the fusebox. 240Z headlight fuses are located in the upper right hand side of the fusebox.

I am the one that makes the headlight relay upgrade harness. SteveJ was definately right in saying "If you have a known bad headlight, replace it. Also make sure you have dual filament headlights."

Never try and diagnose a system that is incomplete. Replace the headlight with a 7" dual filament headlight and better yet, replace both at the same time. If one went out, it's just a matter of time before the other stops working as well.

SteveJ was also correct in saying "If it was brighter when you used the switch, the circuit was probably working"

Start with replacing BOTH bulbs then go from there. Replace the 2 upper right fuses with 10 amp glass fuses cause they're probably pretty damn old anyways.

Let us know what you come up with or what the diagnoses ends up being.

Dave.

[superfunk]

Thanks,

Thats was exactly the info I was looking for. I'm going to get some new lights tomorrow, I'll let you guys know how it works out.

Adam

Oh, and by the way, its a '71

[SteveJ]

Thanks, Dave. I was too tired to search myself. I forgot about the old axiom about replacing both headlights. It's relatively cheap to do that anyway.

Superfunk - I STRONGLY recommend Dave's relay conversion sight unseen. I did it the old fashion way since my wiring harness was not exactly stock anyway. His is plug & play. The difference with relays is astounding. You'll be willing to drive at night with the mod.

[superfunk]

. You'll be willing to drive at night with the mod.

Ok, that comment is kinda scaring me... How bad are these headlight circuits? Is it a problem with the switch heating up. Im not sure how stock my wiring is because looking at it, it seems to have been hacked at a few too many times.. its a real mess. Anyways, the basic operating of these relay conversion circuits? Do you take the power that would go to the lights and use that to activate the relay which will have the lights on a different high amperage circuit. This would protect the switch.

[Zs-ondabrain]

The relays are powered from directly off the battery, and yes, the relays are controlled by the headlight output plug for the right headlight. The relay upgrade harness will plug right into your existing system without modifying anythind and will reduce the amperage flow thru your fusebox and headlight switch by over 98%

they are $125 for the Harness.

The parking light upgrade harness is only $37 and will also stop the parking light fuse from melting your fusebox and destroying your combo switch.

wolfin32z@yahoo.com if you need more info.

Dave.

[SteveJ]

Ok, that comment is kinda scaring me... How bad are these headlight circuits? Is it a problem with the switch heating up. Im not sure how stock my wiring is because looking at it, it seems to have been hacked at a few too many times.. its a real mess. Anyways, the basic operating of these relay conversion circuits? Do you take the power that would go to the lights and use that to activate the relay which will have the lights on a different high amperage circuit. This would protect the switch.

Before I converted the headlight circuit to relays, I was getting 9.5 volts at the right headlight with the car off. That's a pretty significant drop.

In addition to what Dave said on the benefits of the parking light relay, it takes a BIG strain off your combo switch, especially when coupled with the headlight relays. The headlight relays also take strain off your dimmer switch.

These are old cars. Wiring and switches are subject to corrosion. It's just a matter of fact. It doesn't matter if it's a Z car, Mustang, Camaro, etc.

[superfunk]

Well I replaced both my lights today with new haolgens. Nothing has changed. A quick check with a voltmeter shows no power going to the light. Fuse is good, and I replaced it/cleaned the contacts to make sure. So I guess im chasing the wiring. Any tips?

[Zs-ondabrain]

hopefully a little Datsun 101 will help you out. If any of this confuses you, let me know.

your right headlights power wire is solid red (+)

your left headlights power wire is red/yellow (+)

lowbeams are red/black on both sides (-)

highbeams are red/white on both sides (-)

the engine harness's headlight plugs are white and square and have the tree above wires in it.

_________________________________________________________________

The combo switch has a large white/red wire on the top half of the switch that gets full time voltage. The headlights output from the combo switch is the the large red on the same switch. That wire goes to the fuse box and is split into two fuses. One for the Left headlight and one for right headlight.

The turn signal has a tall white switch located close to the steering column that controls the HI and LOW beams.

It has a center black, ground wire. The red/white is high beam and the red/yellow is the low beam. These are all ground wires or at least the switch only controls the negative side of the headlights. The red/white has a small lead wire that triggers the High beam indicator light in your speedometer that is located behind the dash.

The low beam wire goes directly form the T/S's hi/lo switch to the headlights.

The high beam circuit has a passing relay on most Automatic 240Z's.

Mind you that the wires do change colors every once in a while so you need to follow them closely. but at least knowing what the general purpose and location or direction of each wire will help in diagnosing a problem.

_______________________________________________________________

SUPERFUNK.

Now that you know that the left headlights main power wire is red/yellow, you can follow it to the fuse box. the Left headlight fuse is the upper right top fuse in a 240Z fusebox. The right headlight fuse is under that one.

I personally don't know what wire feed both of the headlight fuses under the fusebox. Some one here has a loose fusebox and can tell you. but that wire will go to the combo switch.

HERE'S WHAT I WOULD DO FIRST.................

I'd use an ohms meter to check the wires between the actual headlight plug (located in the headlight bucket) to the white plug located in front of the radiator. then move onto physically checking the wires that go into the white plugs by giving them a tug, individually. To make sure there is not a break at the plug.

Next, I'd turn on the headlights, test for power at the red/yellow wire. if there is power (+) then test for ground (-) on the red/black and red/ white. Make sure to flip the hi/lo switch for testing each of those wires.

If the right headlight works. then the (-) break can be NO FURTHER than 2 feet away. the wires go to the right headlight first, then to the left so that'll shorten your search.

If the red/yellow wire is the culprit (+), it only goes from the left headlight, to the fusebox. don't forget to check the plug located on the upper right hand side of the passenger kick panel (Inside) it'll still be red/yellow.

Don't forget to check the red/yellow as it comes out of the fuse bux. reason being is the all can look fine up top but be fried under the fuse box.

SOMETHING IN THIS SHORT BOOK OF INFO WILL SOLVE THE PROBLEM. And it takes very little effort to track a bad wire in a 240Z. Especially when it's a larger gauge wire like the headlight wires.

Hope some or even all of this helps. MAN.... I feel like Enrique when I write like this.

Dave.

[superfunk]

WOW!!

Zs Thanks for that post. You saved me a heck of alot of figuring out whats going on and which wire is doing what. I probably wont have time until saturday to tackle this, but it should be a breeze with all the info you gave me there...

Once again, thanks.

Adam

[Zs-ondabrain]

No problem Adam. Besides, how do think I learned about this stuff? My Z had a fare amount of Previous Owner problems and I went at 'em head first.

Luckily, I learned alot on the way.

I run a Datsun Based business at home. I offer a Combo switch and turn signal service and repair. If you find that your switches need servicing, I only charge $40 to almost completely rebuild them and make them as good as new. But you'd have to send them to me, I do my thing, then send them back. It's about a 1 week thing (from the time you ship them to the time you get them back = 1 week)

I also offer headlight and parking light relay upgrade harness's that'll keep you from having those problems again. The info is below. The PLH Plarking light harness is $37 and works on all 240Z's up to 3/73 and the headlight harness (HLH) is $125. It works on ALL 240Z's with the 3-pin square headlight plug.

Follow the links and let us know what you come up with on the headlight problem.

Best wishes and good luck,

Dave.