Headlight switch issue ('92)
10-09-2009, 12:59 PM
#1
Team Owner
Pro Mechanic
Thread Starter
Headlight switch issue ('92)
Recently, my car started having an issue w/the headlight switch: When I turn the switch from "Off" to "Parking lights", the headlight doors open. I don't believe that they should.
I have determined that there is one wire that is fed power (or not) depending on the switch's position, that runs to the head light module. White wire at the Terminal C IIRC. Anyway, when the switch completes the circuit from power, to the headlight module white wire, the doors close or stay closed. When that circuit is broken or open the doors open.
The switch has continuity in the "off" position between the power terminal, and the headlight module (white wire) terminal. The doors are closed. When I move the switch to the "Parkign lights" position, the circuit between the same two pins is open; doors open. If I Jumper the power-to-white wire pins in the harness connector, the doors close. Remove the jumper, doors open.
So the problem appears to be in the switch. I disassembled the switch, and now I am more confused. Nothing looks broken, worn out, contacts look fine, and the switch looks like it's designed to work as it does NOW, not so as to keep the doors closed, in the parking lights position.
Can anyone shed some light on this? Here are some pics....
IN THIS PIC, I am pointing at one of the contacts (the main contact) that supplies POWER to the switch.
In THIS pic, I'm pointing at the contact that goes to the white headlamp door module. For the doors to stay closed, the POWER contact, and this contact need to be closed by the sliding contacts to the right. Hard to see in the pic, but the contacts aren't long enough to reach the Door module contact, by the time the slide, has moved far enough to reach the parking lights position (in the middle of it's travel).
So as I said before, the switch LOOKS like it's operating as designed. What am I missing? Is there something missing in the contacts, that I don't know is supposed to be there?
-Tom
I have determined that there is one wire that is fed power (or not) depending on the switch's position, that runs to the head light module. White wire at the Terminal C IIRC. Anyway, when the switch completes the circuit from power, to the headlight module white wire, the doors close or stay closed. When that circuit is broken or open the doors open.
The switch has continuity in the "off" position between the power terminal, and the headlight module (white wire) terminal. The doors are closed. When I move the switch to the "Parkign lights" position, the circuit between the same two pins is open; doors open. If I Jumper the power-to-white wire pins in the harness connector, the doors close. Remove the jumper, doors open.
So the problem appears to be in the switch. I disassembled the switch, and now I am more confused. Nothing looks broken, worn out, contacts look fine, and the switch looks like it's designed to work as it does NOW, not so as to keep the doors closed, in the parking lights position.
Can anyone shed some light on this? Here are some pics....
IN THIS PIC, I am pointing at one of the contacts (the main contact) that supplies POWER to the switch.
In THIS pic, I'm pointing at the contact that goes to the white headlamp door module. For the doors to stay closed, the POWER contact, and this contact need to be closed by the sliding contacts to the right. Hard to see in the pic, but the contacts aren't long enough to reach the Door module contact, by the time the slide, has moved far enough to reach the parking lights position (in the middle of it's travel).
So as I said before, the switch LOOKS like it's operating as designed. What am I missing? Is there something missing in the contacts, that I don't know is supposed to be there?
-Tom
Last edited by Tom400CFI; 10-09-2009 at 01:26 PM.
10-11-2009, 05:11 PM
#3
Team Owner
Pro Mechanic
Thread Starter
I'm pretty sure that the problem is in the Headlight Door Module.
According to the wiring diagrams that I have, the switch is functioning as designed.
That is, as I understand it:
When in the "OFF" position, the headlight switch closes a circuit between power and the "white wire" that goes to the HDM. -This closes the doors.
When in the "Parking lights" position, the headlight switch does nothing w/regard to the HDM: All circuits pertaining to the HDM are OPEN. This is how MY switch works, and also agrees w/my understanding of the diagrams.
When in the "HEADLIGHTS ON" position, the switch closes a circuit between power and a YELLOW wire, that also runs to the HDM (among other things), and I beleive is supposed to signal the HDM to opend the doors. My switch does this, and that is correct operation per my understanding of the diagram.
I had never paid much attention to the door operation before they started acting up, but studying the diagrams, it appears that when "OFF" the doors should close. When Head Lights ON, the doors should open, and when in PARKING LIGHTS, The doors should stay in what ever position they were in from the headlight switch's LAST POSITION. Yes? No?
There are no shorts to power, on either the white wire or the yellow wire (going to the HDM). So, I'm thinking that the problem is either:
1. I can't read a wiring diagram or
2. The problem is w/in the HDM.
According to the wiring diagrams that I have, the switch is functioning as designed.
That is, as I understand it:
When in the "OFF" position, the headlight switch closes a circuit between power and the "white wire" that goes to the HDM. -This closes the doors.
When in the "Parking lights" position, the headlight switch does nothing w/regard to the HDM: All circuits pertaining to the HDM are OPEN. This is how MY switch works, and also agrees w/my understanding of the diagrams.
When in the "HEADLIGHTS ON" position, the switch closes a circuit between power and a YELLOW wire, that also runs to the HDM (among other things), and I beleive is supposed to signal the HDM to opend the doors. My switch does this, and that is correct operation per my understanding of the diagram.
I had never paid much attention to the door operation before they started acting up, but studying the diagrams, it appears that when "OFF" the doors should close. When Head Lights ON, the doors should open, and when in PARKING LIGHTS, The doors should stay in what ever position they were in from the headlight switch's LAST POSITION. Yes? No?
There are no shorts to power, on either the white wire or the yellow wire (going to the HDM). So, I'm thinking that the problem is either:
1. I can't read a wiring diagram or
2. The problem is w/in the HDM.
10-11-2009, 05:26 PM
#4
Race Director
I had never paid much attention to the door operation before they started acting up, but studying the diagrams, it appears that when "OFF" the doors should close. When Head Lights ON, the doors should open, and when in PARKING LIGHTS, The doors should stay in what ever position they were in from the headlight switch's LAST POSITION. Yes? No?
At least that is how my '96 works.
Turn headlight switch to parking lights, and only parking lights come on.
Fog lights will also come on in this position if the fog light switch is on.
Turn headlight switch to headlight and doors open and headlights come on.
Turn switch back to parking lights and headlights go out, but doors will remain open.
Turn headlight switch back to off, and doors will close and parking lights go out.
