[SOLVED]1998, replaced Lamp module, still park lamps on.

[emarkay]

A few months ago, I had a buzzing relay under dash and traced it to the lamp module, with and flickering parking and headlamps, with ignition and lamps off (car unattended). Shop manual said replace lamp module. Replaced that and all was fine, for a while, then it did it once again (buzzing, but this time with no flickering) for a short while and then it stopped.

Since then, it has been OK for ( a few months or so), but I came home tonight to the park lamps on all by themselves. No buzzing, or other indications, just park lamps on. No amount of moving switches, manipulating the stalk, or starting engine, or shining flashlight into light sensor, nor a few shots of vintage "tuner cleaner" on the multifunction switch and dimmer and twilight controls made any difference. I had to pull the single row power connector on the lamp module, and all is OK now, but of course no headlamps, etc.

What is causing this - I don't want to have to manually wire a bypass to make the headlamps work like a 1957 Chevy, or put a big toggle switch to kill power to lamp module when not driving car!

Anyone else had this happen? The car is in excellent condition, with 78K miles or so.

Thank you!

[Randy T.]

Did you use a new or used LCM? I would not rule out the possibility of the LCM going bad again. It could also be your multifunction switch, I know you sprayed it with cleaner, but you have to pull the boot back and use a good air compressor to blow it out. Little metal flakes build up in the electrical grease and eventually cause a short. If the compressed air does not fix it, you can repair or replace the MFS, your choice.

MFS Dissection


I have a stack of LCMs if you need another.

[emarkay]

Thanks - it was "used for 6 months"... but did seem to be pulled from a car - had the usual "junkyard sharpie" marks on it, but was only $100. (I know...) What is your experience with these - the seem pretty robust, is it thermal, grounding, surges or what that seems to be their fail mode? I have the old one here still - know anyone that has any test specs on them?

I will get my compressor out and blow hard on the switch - it does seem a bit "floppy", but then again I don't have reference to what it should be..

For now I am looking into a good toggle switch, to kill power to module - leave it off when away (also a "can't steal me at night if you can't see anything") and flip on when in the car. I am going out to investigate now.

Do you really have to disable the SIR and pull the steering wheel to get that switch out? I have been staring at the shop manual too much; is there a cheat? Maybe a "cut plastic here" or "drill hole here" so you don't have to pull all that? I am pretty good with hole plugs and epoxy...

Thank you again!!!
MRK

[emarkay]

Looks like if I use a double pole switch, and break C2-E and H, headlamp and parklamp fuse, even if there is a fault in the ignition feed C2-C, no lamps will light. Hopefully even if the module fails, there will be no current draw on the bulbs, so it seems fail safe, eh? Will look into this further. Still may need to do Multifunction switch, too.
Thanks!
MRK

[sall]

This happened on DD '98. It was the MFS. All I did was hit the holes behind the boot on the MFS with some compressed air. Been fine ever since. New MFS are hard to find. A toggle switch would be okay if it can handle the current unless it just triggers a a relay. I don't have the diagrams handy right now. IIRC the LCM has the relays on board.

[emarkay]

Great point on amperage! Forgot this is the "feed". Found a DPST rated at 25A 12VDC (screw terminals and all) to match the fuse rating, which will be in next week. What about getting the MFS out without removing the steering wheel? Can it be done?

[sall]

I'm sure it can be done w/o removing the steering wheel. It connects at the firewall and the wiring runs up the column. Column cover and likely the knee bolster will need to be removed. I may be over looking something though.

[emarkay]

Switch works - No headlamps, but no battery drain either! A temporary fix for a permanent problem. More elsewhere...