Stupid Electrical Problem With Headlights

[demuire]

It appears that I've got a small problem with my headlights on the Corolla. When the car is off, if I turn the headlights on, the dash highbeam light comes on, but the headlights don't. I can hear the headlight relay click, but the lights don't actually come on.

 

If I turn the engine on, then everything works as they should. If I then turn the engine off with the lights on, the lights stay on.

 

*sometimes* when I turn the lights on (with the engine off), they come on, but most of the time it just brings up the highbeam light...

 

And, if I push the stalk to highbeam, nothing happens. But if I flick it to flash the highbeam, the highbeam comes on.

 

WTF???

 

My two guesses are either:

 

1) bad earth somewhere

2) dodgy headlight relay

 

Any ideas?

[mikeys toy[RL]]

i concur....do you concur?

[demuire]

Dunno. I had a quick look to see if I could spot a loose earth, couldn't find one. Don't have any spare headlight relays to test the one that's there at the moment.

 

Too slack :P

[coln72]

Quick easy fix, just bash the relay with an end of a screwdriver to see if it is just sticking. If nothing happens then look somewhere else.

[demuire]

Bash the relay? Hmm, ok. But you can hear it go "click". It's just that not much else happens. I wonder why it works when the engine is on? Higher voltage? If so, I wonder why it stays on when you turn the engine off? Weird.

[Jason]

Replace the realy with a new one, its quiet easy.

 

Horn realys are rated about 40amps, enough for lights. IIRC they have 3 plugs. one will be common ground.

 

You can get the spade plugs from your local electronics store.

 

Spade Plugs

 

http://www1.jaycar.com.au/productView.asp?...eMax=&SUBCATID=

Edited July 6, 2005 by Jason

[demuire]

Jason: Haha, yes I know how to wire up a generic relay :P

 

I've still got the stock headlight relay in the Corolla, so in order to put in a generic relay (which would probably be a good idea anyway) I'll need to do some rewiring (ie, figure out which wire is which, cut the original plug off and connect the correct wires to the correct pins on the relays). Not very difficult, I know.

[Super Jamie]

you can swap the high beam and low beam circuits (they're just two wires each) to see if it really is the relay causing the problem

 

i had the same problem a while back in the ke25, and it was a broken join in the wire going to the low beam circuit. diagnosed by jiggling the wiring loom

[Xany]

i must say though....i could never figure out the way toyota wired their headlights.....i always became confused and gave up even trying to hook up a relay to put brighter headlights in....

[demuire]

diagnosed by jiggling the wiring loom

 

Tried that too, no difference. Ah well, when it properly stops working I might have a better look at it :P

[mikeys toy[RL]]

bubba did something like this to me; first none of the light would work, then only the left ones would work (high and low)

i wiggled both plugs on both bulbs and they've been working since.....

[Banjo]

i must say though....i could never figure out the way toyota wired their headlights.....i always became confused and gave up even trying to hook up a relay to put brighter headlights in....

 

I'm with Xany. The way Toyota wire up their headlights in the K series is wierd.

 

From what I've worked out, most of the problems seem to be in the light switch unit on the steering column. There's lots of little contacts in there, and close inspection shows that some are carrying a lot of current, which doesn't figure when there is a relay to do all that work. Appears the headlight relay is only for LOW BEAD. The HI BEAM is switched via the stork switch directly without a relay.

 

There is a seperate contact for HI BEAM indicator (blue light) & HI BEAM lights, and HI BEAM flasher, in the switch itself. All very confusing.

 

I found all this out when I lost HI BEAM altogether, but HI BEAM still worked on the HI BEAM flasher.

 

I solved problem by installing a dual relay from SuperAutoCheap and swapping around a couple of wires in the light switch so the lights work in a more conventional wiring manner. The dual light relay has fuses built in.

 

Mount the dual relay up close to the battery & run wires to fusible link & Hi & Lo beams.

 

Result: cuts down the usual voltage drops, as power lighting circuit is relatively short. Oh, my lights are brighter now !!!

 

:P

[demuire]

Banjo: That is the most interesting post I've read on any forum for a long time now. THANK YOU :P

[demuire]

The lights in the Corolla are actually very good. Much much better than the ones in my old pink one anyway. But if I can pull more light, all the better. I should drag out the old wiring diagrams and rewire the lights again :P

 

How did you go about rewiring the switch "in a more conventional manner"?

Edited July 7, 2005 by demuire

[Redwarf]

The lights in mine are pretty good too. Particularly with 100/140 globes....