Head Light Help!

[kournflake]

Hey I just picked up a 83 SX-4 and Im having a issue with the headlights. When I turn them on the rear defrost switch buzzes like crazy and just the taillight/rear running lights turn on but no lights up front work. I replaced all the fuses and relays I could find but nothing helped. Please tell me some one has dealt with this before.

[mudkicker715]

I agree with mernsy. had a nearly identical issue.

[BenM]

There is supposed to be a engine/body ground strap down by one of the engine mounts to bridge the rubber mount. Those are commonly lost or broken.

For some reason all the grounds from the headlights take a torturous path through the wiring harness and back to a ring terminal that I believe is on the firewall somewhere.

Also, the headlight switch itself needs to be grounded (but I don't suspect that's the problem).

What I like to do is find someone who put an amp in their car and bought some insane wiring kit and get a few leftover pieces of heavy gauge wire, put some ring terminals on 'em, and put a wire from the negative terminal of the battery to the body, another in a convenient place from the block to the intake manifold and a third from there to the firewall.

I also find it good to run an extra ground for the front lights from any light ground up front to the body (the back harness has one built in by the plate light).

This is all in addition to the stock ground strap that should be there.

It really does sound like your lights are trying to ground through the switch. I've heard tale of overheated transmission cooling lines where they've been the best ground between the engine and the body.

[kournflake]

so i checked all the grounds and all seems good. i did track the headlight ground back to a fuse or maby a relay right above and to the rear of the batt. what does that little box do and could it be my issue? im kinda broke and cant just buy and replace every thing it could be so im trying to narrow the field. i also upgraded my dis to a hei so the icm is unhooked. its the "relay"? on the right.

[doc65]

In mine that is an A/C relay, the other one (on the the left) is the horn, that's on my 82 SX/4...

[eagle503]

His has the a/c deleted.

[BenM]

so i checked all the grounds and all seems good. i did track the headlight ground back to a fuse or maby a relay right above and to the rear of the batt. what does that little box do and could it be my issue? im kinda broke and cant just buy and replace every thing it could be so im trying to narrow the field. i also upgraded my dis to a hei so the icm is unhooked. its the "relay"? on the right.

Did you end up going through the diode assembly to get there? The headlights and the A/C both trigger the Sol-Vac through there, and would be connected.

Check The Diagram on the EaglePedia to see what I mean.

[kournflake]

No I didn't follow the power just the ground so there where no inline diodes. But that relay is hooked to the ac and the headlights?

[BenM]

I'm not really sure what color that wire is supposed to be from the picture, if it's black then it's the ground, and all the grounds are connected. But I'm pretty sure that's not what you're looking for.

The only relay in the light system is for fog lights if installed, everything else, head lights and parking lights, gets all its power from the switch. It's not like modern cars with relays for everything.

When you follow the ground out of the headlights, the wiring harness doesn't go toward the battery, but toward the bulkhead connector under the steering wheel.

The secondary harness going into the the car on the passenger side is only for the MCU, and there are only a few interconnects.



All the grounds should run separate from each light and meet at a big junction on or near the driver's side fender.

[Jurjen]

The left relay is the manifold heater and the right one the horn relay.
The headlights are not switched by a relay.
The ground "looking" OK is not good enough.
Find the ground connection behind the brake booster on the firewall and remove the nut, clean the contact surfaces with sandpaper and put it back together with some vaseline.

[kournflake]

Thanks for all the input guys. I've been going crazy trying to track down this ground wire behind the brake booster and there just isn't a ground there. Could some one post a few pics? If I could see where the headlight ground starts and stops I think I could fix it. I know there is one. The headlights worked fine before. I just don't get the diagrams. 

[kournflake]

Well I fixed her! Thanks again for all the input. All it needed was a extra ground. So if any one ends up reading this post because there headlights stopped working but taillights still do clean all your grounds then add a extra off the main headlight ground( black / w white stripe) and run to to the body.