door switch problems!! Help...
door switch problems!! Help... Okay guys heres the problem I'm having with my 2000 trans am and I'm not sure if it will be the bcm causing it or what it is. So sometimes when I get in my car in the mornings the interior lights come on when I open the door. Then when I shut the door the interior lights do not go out no matter how long I drive my car. So I thought no big deal its a door switch but before buying the whole locking mechanism, I would like to know a few things where does the voltage come from, what turns the courtesy lights on, and can I buy just the door pin switch instead of the whole mechanism? I should add I did a voltage test on both doors on what I thought was the switch any how on the drivers side i got B+ voltage but on the passenger side I got 2 volts. If you have any idea of what this could be please fill me in.
Joined: Nov 2003
Posts: 11,334
Likes: 347
From: Jacksonville, FL (originally from Toronto Canada)
Well, to start with, you can't replace the pin switch because there isn't one. The door switch is incorporated in the lock mechanism. It's a grounding switch that provides ground as an input signal to the BCM that the door is open. The input wires are grey/black on the left side and black/white on the right side. The ground wire is black on both sides.
The courtesy light system is a closed circuit with the BCM. Power is provided to all interior lamps via a dark blue/white wire at all times except when the BCM goes into sleep or battery saver mode. The variable ground is controlled by the BCM via the white wire. It varies the ground to provide the theater dimming effect when the lights go off. The map light switches simply provide an alternate path direct to ground to turn on the lights when the courtesy lights aren't on.
Before buying the locks, it is usually worthwhile to try cleaning them. Over time the switches get gummed up with grime that can prevent them from functioning correctly. Something like WD-40 can be used to remove the grime and that is often enough to get the switches working again. Also, there is a small amount of adjustment that can be made by loosening the lock fasteners. That sometimes helps as well.
Finally, if nothing else works, try disconnecting each switch individually to determine which one is causing the problem or if a switch is even the problem at all.
The courtesy light system is a closed circuit with the BCM. Power is provided to all interior lamps via a dark blue/white wire at all times except when the BCM goes into sleep or battery saver mode. The variable ground is controlled by the BCM via the white wire. It varies the ground to provide the theater dimming effect when the lights go off. The map light switches simply provide an alternate path direct to ground to turn on the lights when the courtesy lights aren't on.
Before buying the locks, it is usually worthwhile to try cleaning them. Over time the switches get gummed up with grime that can prevent them from functioning correctly. Something like WD-40 can be used to remove the grime and that is often enough to get the switches working again. Also, there is a small amount of adjustment that can be made by loosening the lock fasteners. That sometimes helps as well.
Finally, if nothing else works, try disconnecting each switch individually to determine which one is causing the problem or if a switch is even the problem at all.
Okay thank you so on the drivers door I unplugged the top plug on the mechanism I got to it without removing the door panel the hole that slides over the door pin and anyhow I read the voltage on the drivers side and it read B+. I then went to the passenger side same plug location the voltage was only 2 volts. I will say that I do not know if the lock mechanism has more than one connector so it could be something else. But I'm leaning towards the bcm being bad. Because not only are the courtesy lights being weird but the radio lcd screen that displays time and station and what not it sometimes is dim to where it doesn't look like its on but it will still pickup stations and play music and other times its bright and working like it should. And today I got home from work and then I left in my wifes car and my car was parked lights were not on when we got back maybe 2 hours later the lights were on. So I go out open and shut the doors no affect so I start the car turn it off and get out come inside take a shower come back out the lights are off. Then 15 min later my wife comes to me and says my lights in my car just came back on nobody touched the car its not been a windy day in indiana so I am at my wits end with my car. The one thing I have not done is take the door apart and diagnose it that way because I am scared of breaking the door panel.
Joined: Nov 2003
Posts: 11,334
Likes: 347
From: Jacksonville, FL (originally from Toronto Canada)
The door switch wires are ground switching so any voltage reading you get is basically meaningless. They are used only to provide a ground signal (0V potential) to the BCM to indicate when a door is open.
As I suggested, you should unplug the door switches to see if the problem disappears. That will tell you if one or both of the switches are at fault. If so, reconnect one side and see if the problem comes back. Then do the same with the other side. That will determine which switch (or possibly both) is the source.
If unplugging the two switches doesn't make the problem go away then it is either the BCM or the wiring from the BCM to the switches. If the insulation on the wires is damaged somewhere and grounding out then the system would see that as a door open.
The radio problem you describe is completely unrelated to the BCM. The only relation the BCM has to the radio is the Retained Accessory Power (RAP) circuit - the power that keeps it on after the ignition is switched off until a door is open. That power is either on or off. It does not affect the radio display or the dimming.
Basically, the BCM is the last thing you should suspect - only after eliminating other more likely possibilities.
As I suggested, you should unplug the door switches to see if the problem disappears. That will tell you if one or both of the switches are at fault. If so, reconnect one side and see if the problem comes back. Then do the same with the other side. That will determine which switch (or possibly both) is the source.
If unplugging the two switches doesn't make the problem go away then it is either the BCM or the wiring from the BCM to the switches. If the insulation on the wires is damaged somewhere and grounding out then the system would see that as a door open.
The radio problem you describe is completely unrelated to the BCM. The only relation the BCM has to the radio is the Retained Accessory Power (RAP) circuit - the power that keeps it on after the ignition is switched off until a door is open. That power is either on or off. It does not affect the radio display or the dimming.
Basically, the BCM is the last thing you should suspect - only after eliminating other more likely possibilities.
Okay thanks again so the last question I have, Is there only one connector on the lock mechanism if not which one is the door switch. I'm trying to diagnose this without taking the door panel off but I guess I might as well since I still need to do the staple removal fix so my door panels don't crack
Joined: Nov 2003
Posts: 11,334
Likes: 347
From: Jacksonville, FL (originally from Toronto Canada)
There are two connectors on the lock mechanism. The upper one is for the switch and the lower one is for the power lock actuator. Just check for the wire colors mentioned earlier.
Were you able to get this figured out? My 2002 TA is have the same if not a very similar issue.
My map and dome light goes to a dimmed state but never off. The only way to get them to turn off is to pull the fuse. Once I pull the fuse and reinstall it the lights will stay off until I open the doors or use the key fob. I've pulled the plug on both door switches and the rear hatch and the lights stay on at a dimmed level. If I place a jumper wire in connector when it's not connected to the door switch the light go to their normal brightness. Also like yours mine lights have been turning all all by themselves.
I'm hoping a mouse didn't chew on something because this car sits in the garage 99% of the time. Only has 30k miles but for the last 6 years I have a hard time even putting 200 miles a year on it.
My map and dome light goes to a dimmed state but never off. The only way to get them to turn off is to pull the fuse. Once I pull the fuse and reinstall it the lights will stay off until I open the doors or use the key fob. I've pulled the plug on both door switches and the rear hatch and the lights stay on at a dimmed level. If I place a jumper wire in connector when it's not connected to the door switch the light go to their normal brightness. Also like yours mine lights have been turning all all by themselves.
I'm hoping a mouse didn't chew on something because this car sits in the garage 99% of the time. Only has 30k miles but for the last 6 years I have a hard time even putting 200 miles a year on it.
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