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lights turn on when car is off (?) WTF?

OK. Here's one for the group.

This is my roommate's car and we're havin trouble figuring out what's going on.

Saab 9000 Turbo from 1992

So, here's how the story goes.

I came home one day and parked my car; when I got out I saw my roommate's Saab and the lights were on. In fact, the second I saw them on they turned off. My assumption was that he just gotten home and the lights stay on for a bit when he turns off the car. When I commented about this to him in the house, he responded that he had been home for a while. Weird. Why were his lights on?

Nothing was really thought about it.

Now, we're about 3 months later and the car is spending a lot of time at the curb, as my roommate has been biking to work lately.

All of a sudden, his car's battery is dead.

The ususal assumptions are made; did you leave the lights on? Is it time to replace the battery?

So, the battery was charged; car started. Turned it off for a bit; car started. Didn't seem like there was something wrong with the battery.

A few days later (with the battery having died again), my friend mentions that he saw his headlights go on as he was walking to his car earlier. This reminded me of the earlier situation I mentioned, and we came to the conclusion that the lights are turning on when the car is off (for short periods of time we think).

But why? This is my question.

He thinks it might be a couple of wires that are making contact, but this just doesn't seem to make any sense to me.

Initially, he was leaving the headlights on all the time (as they turn off when you turn off the car). He has since stopped doing this and it has made no difference. The car's lights still come on intermittantly without reason or warning (he tells me he has seen this a couple of times now and they're on for about 10 seconds or so).

Has anyone heard of such a thing, or is the car just haunted?

He has resorted to unhooking the terminals from the battery every time he parks it; this works; however, not an ideal solution.

your opinions and advice are much appreciated.

Andrew

Reply to
Ferney
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I'd look for any system in the car that can turn on the headlights independently of the switch. Maybe a "follow me home" feature or an alarm or something. A fault in one of those can cause this problem.

Colin.

Reply to
Colin Stamp

[...]

I once had the headlights come on when braking. In very general terms, such problems is often due to a poor ground (chassis) connection somewhere.

Reply to
Johannes H Andersen

"Johannes H Andersen" skrev i melding news:40937D6A.EA4A4DA6@sizefitter_n_o_s_p_a_m_.com...

Not related to this, but in 80's Audis, the ignition is somehow connected to the reverse lights. I could put my car in reverse, take out the key and it would run perfectly. When I changed out of reverse, it died. Another had the opposite problem, whenever he put his car in reverse, it would die.

Kristian

Reply to
Kristian Steve Jensen

I think it may well be related. Firstly, it must also be electrical. When you switch something on (reversing lights), something else with poor ground now gets the ground (of sorts) through the object that was switched.

Reply to
Johannes H Andersen

in article Xns94DBEC98AE758Fern@64.59.144.76, Ferney at mferneyNOF' snipped-for-privacy@hotmail.com wrote on 01/05/2004 07:15:

Lights come on when the car is off

I have an oddity on my '89 900 T8 whereby if I leave the fog light switch depressed and the rear defrosted depressed, with the engine off and the headlights off the headlights will flash intermittently.

Have a check and make sure there is nothing left on that could be turned off. Old tired wiring can do all sorts of odd things.

Happy hunting,

Paul

Reply to
Paul Halliday

FWIW I've seen a similar problem - once - on my '97 900, in which the lights are configured (don't know if this is significant) to let me douse the headlights even if the engine is running. Getting out of the car at the office one day I closed the door and the headlights came on (fortunately, reflected in the bumper of the car in front of me; I would never have noticed them otherwise).

Got back into the car, found that the headlight switch (always left in the "ON" position) had no effect. Turned the car on and off with the key and the lights went off; slamming the car door repeatedly didn't cause them to come back on, and I've not seen the problem since then.

You may have discovered a back circuit in the design of the car's controls. Or, as mentioned in the thread, you might have a wiring/grounding problem.

In the same '97 900 described above, you can turn the radio on and off by simultaneously pressing three specific buttons (um...lessee if I can remember: Dolby, tape reverse, and whatever it is that's next to them). Either there's a back circuit, or the logic in the controller chip didn't consider that possibility...or maybe it's deliberate as some type of diagnostic or maintenance function.

Joe Morris

Reply to
Joe Morris

Andrew, It is the light relay, red one I think, in the relay box right in front of the battery. Tap it,clean or replace it. Pull it out for shutting the lights out if necessary. I had the same condition with my 1992

9000CD. I replaced it with a used one and is working right ever since. Good Luck, Bob
Reply to
Robert Johnson

I had the same problem with my 9000. It is the relay. To resolve the problem, flash the lights as you get out of the car to reset the relay. Best fix though is the new relay.

Bob

Reply to
The Brown & Ollis-Brown Family

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