New Member. Electrical Fault Question

[miklic]

Hello

Second post with other question: When I purchased the Toyota Previa (1993 2.4 L GL), the vendor acknowledged an electrical fault which I shall try to describe:

The sidelights (parking lights) and rear lights stay on even when the key is removed from the ignition and external lights turned off at stalk. A temporary fix has been to remove the fuse for the internal dome light (which also serves the radio, central lock, clock etc. and provides permanent current to these). When this is done, the side lights still work normally when the external lights are switched on at the stalk. When the external lights are switched on, the dome, radio and central lock then get current as well, so I can then operate them. To summarise:

1. Sidelights and rear lights are permanently on.

2. Fuse for domelight removed. Most internal stuff do not work

3. Sidelights and rear lights operate normally when switched on (without dome fuse).

4. When this is done, power is available to domelight, radio, clock , central lock etc.

I suspect that there is some kind of short circuit (or poor earthing?) but do not have a clue where to start looking.

Any suggestions on how to cure the problem will be much appreciated.

Thank you in advance.

Miklic

[T600]

Welcome Miklic.

That's certainly an interesting problem. I think you're on the right lines with short circuit or bad earth, but where indeed?

One thought I have is that there's probably a wire from the lighting circuit to the headunit that tells the headunit when the lights are on (as many dim their displays when the lights are on). I think if that were connected to the radio power feed then that could possibly cause your problem. If the head unit has been upgraded then I'd say this is a likely possibility, but otherwise probably not.

And that's just a guess - as you've already realised, finding the actual cause could take quite a bit of trial and error.

PS have you got a circuit diagram - that might help you to figure out the possible cause. If you haven't someone here can probably point you in the right direction to find one somewhere on t'internet.

Good luck. Let us know how you get on.

[miklic]

T600

Thank you for your response. I think that it is not the wires to the stereo as I changed the stereo myself yesterday (thanks to another post seen in this forum). The original Toyota loom is still there and the stereo was a straightforward replacement. So the fault is probably not due to a previous aftermarket installation. BTW the fault was there before and after I swapped the stereo - not my doing :).

I should probably get a Haynes manual but I am not sure whether wiring diagrams will help me at all.

Thanks again

Miklic

[T600]

Agreed - if it has the original head unit wiring then that's not likely to be the cause.

Wiring diagram might help you work out with what should be earthed, and whether there are any other likely connections between the lighting circuit and the dome items. But they're not usually very specific about where the actual connections are, so may still be a case of trial and error.

I don't think you need to buy a manual to get them though; many Toyota manuals are available on-line. I know where to find them for my cars, but not for the Previa unfortunately. Hopefully another Previa owner will know.

That said, if the Hayes manual was available for any of our cars I'd buy it anyway as they're certain to be helpful at some point if you work on your car yourself.