Rear Hatch Light Mystery
04-01-2006, 09:49 PM
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Rear Hatch Light Mystery
My rear hatch light stays on....all of the time. I disconnected it so that the rest of the lighting system works. I then replaced the plunger switch for the light in the rear hatch receiver. Plug the thong back into the harness and it still keeps everything on......ground. I push the white tipped plunger all of the way down by hand to make sure the plunger switch opens and the light still remains on. This is a mystery...any ideas guys? 86.5 928S. 
04-01-2006, 10:00 PM
#3
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The rear hatch switch controls all the light not just that one so see if its working to switch the rest of them?
Does the light work in the other switch position too? The light itself or its connections can easily be reversed. You will have the take the light out and look at it...
One position of the switch should always be on - so maybe thats the way you have it?
Alan
Does the light work in the other switch position too? The light itself or its connections can easily be reversed. You will have the take the light out and look at it...
One position of the switch should always be on - so maybe thats the way you have it?
Alan
04-01-2006, 10:18 PM
#5
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Oh and don't feel bad! I had the same problem right after I got my first 928. Dang light wouldn't go out, must have bumped it getting stuff out of the hatch and turned it on. So I tried opening and closing the hatch, tried locking it with the key to kill the light, but nothing worked. Came back later to get the owners manual out of the car, and when I opened the drivers door the alarm started going off. 
Couldn't figure out how to shut that off either, till I opened the hatch with the key.
Couldn't figure out how to shut that off either, till I opened the hatch with the key.
04-01-2006, 10:32 PM
#6
Nordschleife Master
The interesting part of the interior lights is that the 12V to each light is hot all the time. The switch control whether the other end of the bulb goes to a constant ground ("on"), the switched ground ("on" with doors/hatch) or nothing. The two door switches and the hatch all connect the same switched ground to the chassis.
04-01-2006, 10:41 PM
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Yes, I know about the light being a 3-way switch. That's not the problem me thinks. It's got more to do with GlenL's post I think. Somehow the ground is not working and the car thinks the hatch is always open. I'll try to switch the leads at the light...thaks guys.
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04-01-2006, 10:43 PM
#8
Race Director
All the lights are three postion....center is off....rock up (towards trunk on center light )is light on when a door opens...rock down is light on all the time...the doors are the same with the switch....
Whats funny is my trunk light does not work in the up position....doesn't come on when any of the doors open...but it will turn on when its rocked down? Odd?
Whats funny is my trunk light does not work in the up position....doesn't come on when any of the doors open...but it will turn on when its rocked down? Odd?
04-01-2006, 10:56 PM
#9
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Those light belong in a lawn tractor. Mine in the rear hatch caused a fire and I had to replace the harness. They often short because it has contant (oops)anode.
04-02-2006, 01:14 PM
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BlueMaxx,
If you want to solve it you have to listen & think... understand how its supposed to work... Glens post was correct - however your interpretation isn't... think about it...
All the lights are wired the same, all the switches (door/hatch) control all the lights => so they should all work the same...
Each light has 3 connections to it.
One end of bulb is always connected to Batt+ via interior light fuse.
the other end goes to the pole connection of the switch integrated into the bulb housing. This switch has 3 positions:
Middle position - is always off - bulb is unconnected
One side position is permanent Ground - bulb is on and stays on (always)
Other position is a switched ground switched by doors (via relay) & hatch (directly).
The door lights have a separate switch beside the lens, the roof & hatch switches have a rocking lens that acts as the switch. The roof style can be installed reversed so you never know which way is permanet ground vs switched ground (also these connections often get swapped after light removal anyway.
2 Options:
A) Test its operation (assuming it works correctly)
B) Take the light out of the car and determine in which direction the bulb end is connected to pemanent Ground (the brown wire).
The switched ground is connected between all lights and the hatch switch & relay outputs so if it were always grounded all the lights should be on at the same time if they are in the switched ground mode (as presumably they normally would be...)
Having a sinle light fail always off is possible based on a failed bulb, failed switch or broken connection at the light fitting.
Having a single light fail always on is impossible - the center switch positioin should always be off - regardless of anything else... (unless messed with)
A single light failing permanently on in the switched ground mode is highy uncommon - this requires the switched ground to be disconnected from the other swiitched grounds AND shorted to ground - possible but very-very unlikely (unless someone messed with it...)
To debug you will have to see what the light is doing... check the switched operations if its always off on one of the side connections that is probably whats broken....
Try all 3 switch positions and tell us what happens in each...
Alan
If you want to solve it you have to listen & think... understand how its supposed to work... Glens post was correct - however your interpretation isn't... think about it...
All the lights are wired the same, all the switches (door/hatch) control all the lights => so they should all work the same...
Each light has 3 connections to it.
One end of bulb is always connected to Batt+ via interior light fuse.
the other end goes to the pole connection of the switch integrated into the bulb housing. This switch has 3 positions:
Middle position - is always off - bulb is unconnected
One side position is permanent Ground - bulb is on and stays on (always)
Other position is a switched ground switched by doors (via relay) & hatch (directly).
The door lights have a separate switch beside the lens, the roof & hatch switches have a rocking lens that acts as the switch. The roof style can be installed reversed so you never know which way is permanet ground vs switched ground (also these connections often get swapped after light removal anyway.
2 Options:
A) Test its operation (assuming it works correctly)
B) Take the light out of the car and determine in which direction the bulb end is connected to pemanent Ground (the brown wire).
The switched ground is connected between all lights and the hatch switch & relay outputs so if it were always grounded all the lights should be on at the same time if they are in the switched ground mode (as presumably they normally would be...)
Having a sinle light fail always off is possible based on a failed bulb, failed switch or broken connection at the light fitting.
Having a single light fail always on is impossible - the center switch positioin should always be off - regardless of anything else... (unless messed with)
A single light failing permanently on in the switched ground mode is highy uncommon - this requires the switched ground to be disconnected from the other swiitched grounds AND shorted to ground - possible but very-very unlikely (unless someone messed with it...)
To debug you will have to see what the light is doing... check the switched operations if its always off on one of the side connections that is probably whats broken....
Try all 3 switch positions and tell us what happens in each...
Alan
04-02-2006, 04:14 PM
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2 threads that helped me solve my similiar problem.
"Testing light delay relay"
"Interior Lighting questions"
Do a search on those two Items and hopefully it will help.
It ended up the rear hatch was on my Delay Relay, takes about 30 seconds for light to go out once trunk lid closed. And switch wasn't get closed enough for consistent operation.
"Testing light delay relay"
"Interior Lighting questions"
Do a search on those two Items and hopefully it will help.
It ended up the rear hatch was on my Delay Relay, takes about 30 seconds for light to go out once trunk lid closed. And switch wasn't get closed enough for consistent operation.
04-02-2006, 04:22 PM
#12
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Originally Posted by BlueMaxx
Yes, I know about the light being a 3-way switch. That's not the problem me thinks.
04-02-2006, 10:44 PM
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Alan...ok...here goes. I will try to be clearer in my description. When the harness to the hatch light is unplugged all other lights in the car work as expected. All three position on all bulbs do exactly what they are suppose to. position(1) allways on, center position always off, position (3) on when door opens, delayed off with doors closed.
Connect the harness to the hatch light and all lights in the car are on and NEVER go off when all doors are closed.
The hatch light itself is always on in position (1), always off in center position, and always OFF in the third position ( this should not be). No matter what position the bulb switch is in, i.e. 1,center or 3, if the harness is connected, all other lights in the car stay ON even when all doors are closed.
The plunger switch on the rear hatch receiver grounds when the hatch is open and moves down and appears to disconnect the ground when the hatch is closed via the plunger in the rear hatch receiver.
I played with this plunger moving it up and down several times and noticed that sometimes it turns the lights out when it is pushed and sometimes it doeasn't, in other words it's function is unpredictable. I suspect that means that the contact is dirty in the rear hatch receiver switch but this switch is brand new.
I'll put a meter on it tommorow and see why it's so sporadic.
Connect the harness to the hatch light and all lights in the car are on and NEVER go off when all doors are closed.
The hatch light itself is always on in position (1), always off in center position, and always OFF in the third position ( this should not be). No matter what position the bulb switch is in, i.e. 1,center or 3, if the harness is connected, all other lights in the car stay ON even when all doors are closed.
The plunger switch on the rear hatch receiver grounds when the hatch is open and moves down and appears to disconnect the ground when the hatch is closed via the plunger in the rear hatch receiver.
I played with this plunger moving it up and down several times and noticed that sometimes it turns the lights out when it is pushed and sometimes it doeasn't, in other words it's function is unpredictable. I suspect that means that the contact is dirty in the rear hatch receiver switch but this switch is brand new.
I'll put a meter on it tommorow and see why it's so sporadic.
04-02-2006, 10:46 PM
#14
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I had a similar problem and the easy fix was to replace this small hatch switch. Mine worked sporatically as you describe as well. Solved everything and again, Alan solved it.
Rod
Rod
Originally Posted by BlueMaxx
Alan...ok...here goes. I will try to be clearer in my description. When the harness to the hatch light is unplugged all other lights in the car work as expected. All three position on all bulbs do exactly what they are suppose to. position(1) allways on, center position always off, position (3) on when door opens, delayed off with doors closed.
Connect the harness to the hatch light and all lights in the car are on and NEVER go off when all doors are closed.
The hatch light itself is always on in position (1), always off in center position, and always OFF in the third position ( this should not be). No matter what position the bulb switch is in, i.e. 1,center or 3, if the harness is connected, all other lights in the car stay ON even when all doors are closed.
The plunger switch on the rear hatch receiver grounds when the hatch is open and moves down and appears to disconnect the ground when the hatch is closed via the plunger in the rear hatch receiver.
I played with this plunger moving it up and down several times and noticed that sometimes it turns the lights out when it is pushed and sometimes it doeasn't, in other words it's function is unpredictable. I suspect that means that the contact is dirty in the rear hatch receiver switch but this switch is brand new.
I'll put a meter on it tommorow and see why it's so sporadic.
Connect the harness to the hatch light and all lights in the car are on and NEVER go off when all doors are closed.
The hatch light itself is always on in position (1), always off in center position, and always OFF in the third position ( this should not be). No matter what position the bulb switch is in, i.e. 1,center or 3, if the harness is connected, all other lights in the car stay ON even when all doors are closed.
The plunger switch on the rear hatch receiver grounds when the hatch is open and moves down and appears to disconnect the ground when the hatch is closed via the plunger in the rear hatch receiver.
I played with this plunger moving it up and down several times and noticed that sometimes it turns the lights out when it is pushed and sometimes it doeasn't, in other words it's function is unpredictable. I suspect that means that the contact is dirty in the rear hatch receiver switch but this switch is brand new.
I'll put a meter on it tommorow and see why it's so sporadic.
04-03-2006, 12:25 AM
#15
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OK this more complete picture really helps...
Rod - I don't think its quite so easy this time..
BlueMaxx - just to be sure - disconnect the quick connect contact to the hatch switch does it still always come on? Also try grounding that connection to the chassis - do all the lights come on reliably when you do that? - its possible you have another bad switch - but prob. not that likely if its new...
Seems more likely you have a short to the chassis in the rear hatch wiring on the switched ground line and maybe also a partial open on the hatch switch connection?
Look at where the flat cable enters the hatch area (hatch to roof) does it look damaged (sometimes it gets damaged when folks try to remove the trim with a trim tool (or a knife/screwdriver) or they start it and then the flexing eventually finishes the job...
To really check this out - if its not obvious at the edge - you will have to remove the hatch interior trim - awkward to do (and reinstall) unfortunately
Alan
Rod - I don't think its quite so easy this time..
BlueMaxx - just to be sure - disconnect the quick connect contact to the hatch switch does it still always come on? Also try grounding that connection to the chassis - do all the lights come on reliably when you do that? - its possible you have another bad switch - but prob. not that likely if its new...
Seems more likely you have a short to the chassis in the rear hatch wiring on the switched ground line and maybe also a partial open on the hatch switch connection?
Look at where the flat cable enters the hatch area (hatch to roof) does it look damaged (sometimes it gets damaged when folks try to remove the trim with a trim tool (or a knife/screwdriver) or they start it and then the flexing eventually finishes the job...
To really check this out - if its not obvious at the edge - you will have to remove the hatch interior trim - awkward to do (and reinstall) unfortunately
Alan