Lights coming on all on there own

[Steve440]

I just got home and soon as I opened the door the headlights came on. They have now gone off after about a minuite.

This happened the other day when I was at the petrol station and also when I was at the supermarket Tuesday.

I know there is a way of getting them to come on so I can get to the front door in the dark but as I dont know how this is done I am sure it must be something going wrong.

Its a 2002 Aero Estate

Any ideas?

Steve

[sean treacy]

i know this wont be much help to you but mine do this also from time to time.mine is also a my2002 aero with bi xenons.i dont worry too much as they do go off after a couple of minutes or so.

[Max Headroom]

Getting the lights to stay on is, I think, set up on the SID, and known as 'Follow Me Home'.
Although I know very little about this, it did occur to me it might be worth 'tickling' the system and setting it to "On", then setting it to "Off" after a week or so, and see if that settles it down.

[wrighar]

Something to do with flashing the headlights just before you remove the key from the ignition , but after you have turned off the car...

[sgould]

That's it.  You must be inadvertently touching the headlamp flasher after the ignition has been turned off.  30 secs is the default time time for the "follow me home" lights.

[Steve440]

Nope I am 100% sure I am not touching anything. I reverse into my drive, switch the engine off and take the key out. As I pull the key the lights come on.

At the petrol station the other night I drove in, selected reverse and pulled the key. Same again as I pulled the key the lights came on.

Would the tech 2 store how it has been operated?

Steve

[sgould]

Sounds a bit odd.

Just brainstorming the things that cause oddities.....

Does the barrel of the ignition key come up when you take the key out?

Is the lighting stalk at all loose?

Broken wire?  Do all the steering wheel switches do what they should? And the cruise?

Anyone played with the SID?

Maybe a DICE/TWICE fault?

[sgould]

I've just had a look at the wiring diagram.

I wonder if it's just a faulty dipswitch or the associated relay (8a) being loose inside. If it's operating on its own regardless of the switch?

Otherwise everything seems to be controlled by the DICE.

The only fuse seems to be No.7 in the engine bay.

[Steve440]

Everything seems to work as it should with no loose switches.

I suppose as long as it switches itself off after a few minutes it wont be a problem.

Can get an I get that function switched off if it does cause problems?

What is involved with changing or reprogramming the DICE?

Will look at that fuse at the weekend.

Steve

[sgould]

I was thinking along the lines of a bad connection somewhere.   That's because the "follow me home" is triggered by a quick flash of the lights.  So I suppose that it's possible that a loose connection could mimic a "quick flash" and confuse things.  The fuse is the only item in the circuit apart from the dipswitch, the relay and the DICE.

Unless.....

.... the bulb failure warning "relay" under the bonnet is notorious for failing.  It's downstream of the bits mentioned above, but I wonder if it's failed and is back feeding current.  It fails so often, I'd be tempted to check that first.

[Steve440]

OK great

How do I check the bulb failure warning relay?

Steve

[sgould]

It's the orange "relay" in the fusebox by the battery.  It can really only be checked by substitution.  But the usual fault is cracked solder joints on the base where the connection pins fit.  The red top can be prised off and you can have a look for cracks or corrosion.  But if you know someone with a Saab of the same era, try a swap?  Or just try giving it a wiggle and tap and see what happens?

[Steve440]

I borrowed an orange relay, the car still does this sometimes like before so I doubt its the relay unless that one is faulty as well. Any more ideas?

The odd thing is I did it on purpose last night when I got home, the lights only stayed on for about 30 seconds. When it does it on its own they stay on for about 2 or 3 minutes.

Will Tech 2 be able to know what has triggered it?

Thanks

Steve

[sgould]

Clutching at straws here, but do the sidelights or headlights come on when you hit the brakes?

If so you may have a badly fitted brake light bulb.  The twin filament bulbs can be pushed in too far.  Then they will appear to be OK but they will actually be rotated too far and the base contacts connect between the tail light and brake light circuit.  This can cause all sorts of odd problems with ignition and lighting.  On some cars the engine won't switch off with the ignition if you have your foot on the brake. 

Bit of a long shot, but something fairly simple to check and eliminate.

[Steve440]

Nope just been out with SWMBO and just the brake lights come on. Did a complete light check and all bulbs do as they are supposed too.

As she got out it did the 2 or 3 minute light thing, she had not touched anything. You dont even need to lock it or have had the lights on. Just getting out of the car triggers it, it might have been doing it for ages just only recently noticed it.

If you put the key back in and switch the ignition on and off it stops it straight away.

The odd thing if it was the ''get you to the front door lights'' why is it staying on for 4 x longer than it should?

As they come on they do the up down thing as if I have done it on purpose, is that supposed to happen?

All very odd, if it did it every time I would presume it was an ECU programming thing but something must be getting a false signal I presume but why the long staying on period or is that adjustable by what you do with the stalk?

Steve