Headlights won't go out!

[alexandlol]

(97 XLT 5.0 V8)
This is a strange one. No matter what I do, I can't turn off the headlights or rear lights. They stay on even with keys outs. So, every time I leave the car I have to take out 3 x fuses for left lights, right lights and dash illumination. Then put the fuses back in when I next have to drive (if it's dark, obviously)!

Fiddling with headlight switch on the dash makes no difference. Ditto stalk. Something is still alive in the headlight switch because I get the 'lights on' chime if I take the keys out with the switch in the 'on' position.

A friend suggested a fused relay - but according to the manual there is no relay for the headlights.

Any ideas???

[B33p3r]

My guess is you have auto lamps. There is a slider bar to set the level of abient light your Headlights and dashlights should come on. I've never had autolamps so I can't say how they should work with different settings. By looking at the schematics for a 98, slide the bar to the right which will make your lights come on later(when its darker) as opposed to earlier(when its still quite light out). I guess to best test the auto lamp scenario is to pull the fuse for auto lamps and see if your problem persists. Now that I rambled on, do you in fact have auto lamps?

[alexandlol]

Originally Posted by B33p3r

My guess is you have auto lamps. There is a slider bar to set the level of abient light your Headlights and dashlights should come on. I've never had autolamps so I can't say how they should work with different settings. By looking at the schematics for a 98, slide the bar to the right which will make your lights come on later(when its darker) as opposed to earlier(when its still quite light out). I guess to best test the auto lamp scenario is to pull the fuse for auto lamps and see if your problem persists. Now that I rambled on, do you in fact have auto lamps?

Thanks but I don't think it's the autolamp. I do have it, but no amount of fiddling with the slider bar (that anyway I hadn't touched) makes any difference. Plus, even with autolamp the lights should go out when the car is switched off and with the keys out? Thanks for the message though.

[srercrcr]

I think a component in that upgrade feature is defective. Either track it down yourself or have a shop track it....should be relatively straightforward.

[B33p3r]

The reason I mentioned the autolamps is because it supplies the ground for the headlamp relay. If for some reason the autolamp module was faulty, it could supply the ground circuit for the relay, even though the ignition was not on.
I'm going by the wiring diagrams for a 98 but they should be the same. The power for the auto lamps is taken from fuse 36 of the Interior fuse panel.
The headlamp relay is located in the relay module in the lower center of the dash. In the neighbor hood of beneath the radio. Fuse 11 of the power distribution box(under the hood) feeds the coil of the headlamp relay. The ground for the relay as mentioned above is supplied by the auto lamp sensor and or the RAP module during an alarm condition. Fuse 12 of the power distribution box supplies the 12 volts through the headlamp relay, when the coil is pulled in, to the headlights and park lights.
To test the relay, pull fuse 12 and see if problem goes away. If it does, then your relay is staying pulled in. At this point I'd try a new relay. post back with your results and we'll go from there.

[alexandlol]

Originally Posted by B33p3r

The reason I mentioned the autolamps is because it supplies the ground for the headlamp relay. If for some reason the autolamp module was faulty, it could supply the ground circuit for the relay, even though the ignition was not on.
I'm going by the wiring diagrams for a 98 but they should be the same. The power for the auto lamps is taken from fuse 36 of the Interior fuse panel.
The headlamp relay is located in the relay module in the lower center of the dash. In the neighbor hood of beneath the radio. Fuse 11 of the power distribution box(under the hood) feeds the coil of the headlamp relay. The ground for the relay as mentioned above is supplied by the auto lamp sensor and or the RAP module during an alarm condition. Fuse 12 of the power distribution box supplies the 12 volts through the headlamp relay, when the coil is pulled in, to the headlights and park lights.
To test the relay, pull fuse 12 and see if problem goes away. If it does, then your relay is staying pulled in. At this point I'd try a new relay. post back with your results and we'll go from there.

>>>
Thanks - this is gold dust. I found the relay box under the dash (*not* in the manual!); but can you say which is the headlamp relay? There are six relays in there. BTW I think my 97 wiring must be a bit different - fuse 12 in the PDB supplies the 'air ride relay' (and is anyway absent on my model) However pulling fuse 8, 'headlamp relay' does turn the lights off. I think replacing the relay stands a good chance of working - but which one?? I'm a bit concerned about pulling them out one by one in case I fry the PCM.
Thanks again.

[B33p3r]

Mine shows 7 relays but I'll do my best for you;
_________________________________________
/ \
/ 1 2 5 \
/ 7 \
driver l lpass
l 3 4 6 l
_________________________________________________

1=interior lamp relay
2=headlamp relay
3=one touch down relay
4=park lamps relay
5=battery saver relay
6=dimmer relay
7=Acc delay relay

This is assuming you are looking into the module. Hope it helps. You should be able to pull any of these relays and not hurt your PCM. Also, if you pull two identical relays, you can swap them to see if the problem goes with the relay. 1,2,3 and 4 are identical in my prints. Posting back the final outcome is what makes this site great!

[alexandlol]

Originally Posted by B33p3r

Mine shows 7 relays but I'll do my best for you;
_________________________________________
/ \
/ 1 2 5 \
/ 7 \
driver l lpass
l 3 4 6 l
_________________________________________________

1=interior lamp relay
2=headlamp relay
3=one touch down relay
4=park lamps relay
5=battery saver relay
6=dimmer relay
7=Acc delay relay

This is assuming you are looking into the module. Hope it helps. You should be able to pull any of these relays and not hurt your PCM. Also, if you pull two identical relays, you can swap them to see if the problem goes with the relay. 1,2,3 and 4 are identical in my prints. Posting back the final outcome is what makes this site great!

I have a final outcome! I am an idiot for not working this out sooner, but there was one obvious diagnostic check I missed. Apologies to those earlier in the thread who suggested this.
The autolamp is faulty. I pulled the autolamp fuse and, hey presto, the problem is fixed.
B33p3r - many thanks for helping me find the other relay box, and identifying which is which. This is really useful to know and will no doubt come in handy in the future - can't believe it's not in the manual. I now have a Haynes and EVTM on order!
This forum is great - thanks to all.

[B33p3r]

You may also want to check out alldata.com. You can get info specific to your vehicle. They were the prints I was using. It costs you $ 19.00
for the year and 14.00 for each year after. Or copy and paste into a word document and print yourself a hard copy.