Headlights Staying On

[AN007]

Great stuff.

Do you have your fan control on auto? I think that dictates it but I can't quite remember.

If not, try lowering the temperature slightly next time it faults and see if it lets you then.

I've changed it to every option but nothing.. Its not a major problem so i'll see how goes..

thanks

[therealrem]

I've just had this type of problem on my V-plate IS200 SE. Symptoms as follows:

- Front lights staying on regardless of ignition switch, light stalk or door switch

- Sometimes buzzing headlight relay in engine bay fuse box

- Instrumentation backlights turning on/off from time to time

- Fuel gauge going down to zero and the lamp flashing

- Alarm set itself off once too

I've spent two nights with wiring diagrams and a multimeter and have found the following:

- The headlamp relay works fine (not broken)

- The problem is still there when the alarm ECU is disconnected (so the ECU is fine too)

- The alarm ECU feeds through the rear fog light switch to the relay. I've disconnected this too

- The relay is also fed from the column stalk. If this is disconnected the problem is still there

- The fuse board and wiring behing the drivers side kick plate is dry and not damaged

- The windscreen is the original as far as I can tell

After all this there is still a path to ground on the wire going to the relay coil which shouldn't be there (there is nothing else on that wire - It's completely disconnected). I think that there is a short circuit to ground somewhere on that wire or more likely in the junction box behind the steering column. As far as I can tell this looks like a nice place for water to collect. I've run out of patience so it's going to a local garage tomorrow for the guys to look at. I'llet you know what happens...

Rich

[aaronabbott]

I've just had this type of problem on my V-plate IS200 SE. Symptoms as follows:

- Front lights staying on regardless of ignition switch, light stalk or door switch

- Sometimes buzzing headlight relay in engine bay fuse box

- Instrumentation backlights turning on/off from time to time

- Fuel gauge going down to zero and the lamp flashing

- Alarm set itself off once too

I've spent two nights with wiring diagrams and a multimeter and have found the following:

- The headlamp relay works fine (not broken)

- The problem is still there when the alarm ECU is disconnected (so the ECU is fine too)

- The alarm ECU feeds through the rear fog light switch to the relay. I've disconnected this too

- The relay is also fed from the column stalk. If this is disconnected the problem is still there

- The fuse board and wiring behing the drivers side kick plate is dry and not damaged

- The windscreen is the original as far as I can tell

After all this there is still a path to ground on the wire going to the relay coil which shouldn't be there (there is nothing else on that wire - It's completely disconnected). I think that there is a short circuit to ground somewhere on that wire or more likely in the junction box behind the steering column. As far as I can tell this looks like a nice place for water to collect. I've run out of patience so it's going to a local garage tomorrow for the guys to look at. I'llet you know what happens...

Rich

i had my fuse board and theft ecu replaced and it was fine for a few days then came back,so i hope you find a solution

[therealrem]

i had my fuse board and theft ecu replaced and it was fine for a few days then came back,so i hope you find a solution

I've had the fuse board out and inspected it. I found a bit of corrosion on the '1A' connector which is the one that goes to the engine bay and the light relay. The fuse board looked pretty well sealed and I didn't fancy breaking it open so I scratched off as much of the corrosion as I could with a tiny screwdriver and plugged everything back together. So far everything seems well but I'm not holding my breath!

[aaronabbott]

i had my fuse board and theft ecu replaced and it was fine for a few days then came back,so i hope you find a solution

I've had the fuse board out and inspected it. I found a bit of corrosion on the '1A' connector which is the one that goes to the engine bay and the light relay. The fuse board looked pretty well sealed and I didn't fancy breaking it open so I scratched off as much of the corrosion as I could with a tiny screwdriver and plugged everything back together. So far everything seems well but I'm not holding my breath!

which one is the a1 connector and have you got a pic

[marknewcastle]

hello guys! im having a nightmare with my headlights staying on, As soon as i take my key out of the ignition the lights come on!!!!

It carnt be the relay under the bonnrt as it works fine when the ignition lights are on. Spoke to some guy who said the lights are getting a constant feed when ignition is off....

Ive looked at diagrams and found no dampness in kick panel fuse box..

im lost but just dont want some cowboy auto electrician to charge me a fortune for sorting this out..

any other ideas? Thanks guys

[aaronabbott]

have you tried all the solutions that other people have first

[marknewcastle]

have you tried all the solutions that other people have first

Yep had a good read through all the info, a guy just said to me that the automatic light control relay may be the problem, does this sound right?

[aaronabbott]

have you tried all the solutions that other people have first

Yep had a good read through all the info, a guy just said to me that the automatic light control relay may be the problem, does this sound right?

not to me it dont,have you tried cleaning up all the contacts on the fuse board

[marknewcastle]

Yeah ive had kick panel off and NO moisture at all and contacts are fine, i read 1 post saying there must be a short somewhere which sounds right even though im no car expert by any means.

sooooo im stuck and look like im guna have to pay a auto eletrician stupid money on monday

[aaronabbott]

Yeah ive had kick panel off and NO moisture at all and contacts are fine, i read 1 post saying there must be a short somewhere which sounds right even though im no car expert by any means.

sooooo im stuck and look like im guna have to pay a auto eletrician stupid money on monday

pm sent

[marknewcastle]

thanks for pm mate checked all the pins again and seem fine, still happening!

soooo still lost

[ruairibray]

Had alarm/light ecu replaced and nothing - no water gettin in fuseboard had it checked out..still lost...Lexus garage it looks like!!

[Geoffers]

There is obviously something putting a negative trigger on that line. If you unplug the ECU do the lights stay on?

[aaronabbott]

There is obviously something putting a negative trigger on that line. If you unplug the ECU do the lights stay on?

just had a look and the answers yes

[Geoffers]

I think the only option now is to physically trace were the cable goes and its actual connection points in between. This has to be something silly.

Because the relay only needs a few mA to activate, damp could still be doing this if it is pooled.

If I get to the Midlands meet and the weather is ok we should take a good look. (And a million photo's of possibles for other people with slightly different causes, but the same fault)

[aaronabbott]

cheers geoffers :winky:

[aaronabbott]

been messing around today with it and found my problem is coming from this bottom connector

but cant find what it does

[Steviewevie]

but cant find what it does

Is that on the driver's side ?

[aaronabbott]

but cant find what it does

Is that on the driver's side ?

yeah,every where ive looked shows the fuse box and not the bit that cilps onto it which is holding this plug

[Steviewevie]

yeah,every where ive looked shows the fuse box and not the bit that cilps onto it which is holding this plug

That's what I'm finding too :duh:

[Steviewevie]

How many wires does that grey connector have going into it ?

[aido]

Have you unplugged the connector to see what stops working?

[aaronabbott]

How many wires does that grey connector have going into it ?

10 i think,heres a pic of the actual connector

if i wiggle it the lights go off (ign off) instead of being on

@aido,when unplugged theres a beeping sound

[Steviewevie]

ok I am pretty sure that connector is called IH3. Still trying to find exactly what goes into it.

Edit - see this diagram