Weird electrical problem with car - gurus needed.

[sir.b]

Hey lads,

Through the week I parked my car, walked away and noticed the headlights were on. Weird, middle of the day. I went back and the headlight switch was off! Turned the switch on and off a couple of times and the headlights stayed off.

Went home and told the wife (she drives it to work) it happened and to make sure the headlights are off when she parks it at work, went outside and the headlights were on again. Flicking the switch made them turn off again.

This morning, dead battery. They must have come on again in the middle of the night.

As far as I can tell there's no relay, and the headlights work by routing power directly through the switch. I went to pick a part today to get a new switch but they didn't have any, so I'm just going to clean it up and see how it goes.

Can anyone think of anything else other than the switch itself that could be causing the issue? It's intermittent which makes it difficult to find.

Justin.

[Humbug]

I'd be looking at the elec circuit diagram. It seems abit strange that they don't use a relay for high powered lights.

I'd check to see if it is possible for power to leak in from another circuit.

[sir.b]

I can't find a circuit diagram/workshop manual on the net. I'll have to buy one if I can't nut it out without it. The headlights are coming on full brightness though, they're not flickering or low powered, as if the switch was contacting.

I can't find a relay anywhere on the car, I can't find a replacement relay on the net, supercheap/repco/autobarn had no record of a relay for them on their system, and the switch contacts are pretty solid looking, so I'm definitely leaning towards there not being a headlight relay anywhere. There's definitely no headlight relay in the fuse box, but there are two relays in there for other things.

Justin.

[smiley_666]

whats the car?

[sir.b]

^ I'm a dick, I typed that out and then deleted it in an edit. It's a 95 Ford Laser (same as a Mazda 323).

This is the inside of the switch contacts:



The little black dots are pins that push down depending on the position of a slide on the other side to break the metal contacts. I'm guessing the pins have slightly worn and aren't making the metal break contact intermittently (temperature of the metal contacts perhaps?).

Justin.

[ASTAR]

There will be relay for that year model.

Next time it happens, pull the fuse to see if it's isolated to the loom. Then check to see if the pass light or switch is stuck.

If you really get stuck, give me a call

[Eclipze]

If you can manipulate the switch around to cause the headlights to flicker on (without properly switching it), then I'd suspect a worn switch. But at the same time, I'd hope to see some charring on the switch plates from poor switching. So I'm more suspect of a wiring problem or a faulty hidden relay.

Until solved... while not driving, pull the headlight fuse to avoid flattening the battery.

[sir.b]

Cheers guys. I've had the fuse out for the last couple of hours, what do they say about great minds? The switch *feels* fine, and there's definitely no sign of a "short". The problem behaves like a relay so after Wayne said there definitely should be one I went back down that path.

Wayne you put me onto the right track, I found a workshop manual for the Mazda 323 (basically the same car) and there IS a fucking headlight relay, however, I spent more than 2 hours stripping the car trying to find it and no luck, it's not where the 323 manual says it is

I've found and unplugged about 6 different relays, but none of them kill the headlights

When I find it, I'm going to smash the fucking shit out of it with a hammer.

Justin.

[ASTAR]

When I was working on Mazda's, most of the headlight relays were in the engine bay near the radiator support panel or close to the battery.

Also Mazda around that time had a body control unit that controlled indicators, flasher, headlights and wipers all in one unit. The headlight relay was buried within that.

When you find the relay, you need to see if it works via grounding or active power from the switch. If you disconnect it and the lights go out (whist the switch is off), then you need to see what is activating the relay.

I've seen some weird electrical things in cars and bikes, this might go down as one of them.

If shit hits the fan and you can't fix it, then pop around to my house and I'll go over it (time permitting of course)

[Humbug]

could you put up a copy of the circuit diagram please?