C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1986 Pass. Headlight problem

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Old May 4, 2011 | 06:03 PM
  #1  
86speeddemon's Avatar
86speeddemon
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Default 1986 Pass. Headlight problem

Guys I love this forum you have helped me out of more tight spots than I can ever thank you for. After years of flawless functionality my pass. headlight will not open. Last night the driver side popped up fine the pass. side just sat there. Had to get home so manually rolled it up. Did not grind or bind or anything. When I got home shut her down turned the lights off both went down as pretty as you please. With lights off when you try to manually rool up the headlight the motor catches it and wants to keep it closed. Just will not open on its own checked at the plug to the motor an getting power for it to come up. just no action. Any help would be appreciated.
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Old May 5, 2011 | 01:23 AM
  #2  
Hooked on Vettes's Avatar
Hooked on Vettes
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Default

Originally Posted by 86speeddemon
With lights off when you try to manually roll up the headlight the motor catches it and wants to keep it closed.
That's normal.

Originally Posted by 86speeddemon
checked at the plug to the motor an getting power for it to come up.
What voltage readings did you measure and on what wires?

For the passenger side headlight door motor to open, with the motor
plug disconnected turn on the headlight switch to the Head position.

You should measure 12 volts with the Red meter probe on the Dark Green/White wire and the Black meter probe on the White/Black wire.

Here's the schematic and troubleshooting procedure posted by Agent 86.

http://members.shaw.ca/dankai/Headlight%20Doors.pdf
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Old May 5, 2011 | 08:05 AM
  #3  
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Default

Originally Posted by 86speeddemon
Guys I love this forum you have helped me out of more tight spots than I can ever thank you for. After years of flawless functionality my pass. headlight will not open. Last night the driver side popped up fine the pass. side just sat there. Had to get home so manually rolled it up. Did not grind or bind or anything. When I got home shut her down turned the lights off both went down as pretty as you please. With lights off when you try to manually rool up the headlight the motor catches it and wants to keep it closed. Just will not open on its own checked at the plug to the motor an getting power for it to come up. just no action. Any help would be appreciated.
I just did this dance on an 87....same motors.
If the relays are good, the cycling problem is internal with the limit switches. There are 2...for each direction. One side is worn and breaking contact not sending power to the motor, so the system thinks its supposed to stay closed and will try to close if you open it manually with the ****...
You have to unplug the motor in this case to manually open, then simply plug it in to close.

Open the motor up, look at the contact breaker points on either side of the armature, opposite side of the gear box and see which is loose or soft or just dirty & corroded or worn.. The contacts need a good amount of spring tension against them so they do not try to open too early. I fought this for over a week and must have pulled that motor apart 10 times until I finally figured out the spring tension is the key. As the motor hits the end of its travel, the armature torques up and binds, slides one way or the other to open the points, stopping the power. Loose points open the instant the motor tries to turn stopping it before it moves, or never allows it to move/open. File the points and bend the spring so its tighter. Don;t worry,...there is more than enough torque to break the points open at the end of motor travel.
Try NOT to lift the armature out of the housing. If you DO...then you have to re-insert the spring in the correct slots for it to have proper pressure on the armature. IF the motor clicks after assembly when tested...there is a set of points too loose. Or the spring is not set right. Go Back.
Note the placement BEFORE disassembly.
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Old May 9, 2011 | 08:22 PM
  #4  
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Originally Posted by leesvet

Open the motor up, look at the contact breaker points on either side of the armature, opposite side of the gear box and see which is loose or soft or just dirty & corroded or worn.. The contacts need a good amount of spring tension against them so they do not try to open too early. I fought this for over a week and must have pulled that motor apart 10 times until I finally figured out the spring tension is the key. As the motor hits the end of its travel, the armature torques up and binds, slides one way or the other to open the points, stopping the power. Loose points open the instant the motor tries to turn stopping it before it moves, or never allows it to move/open. File the points and bend the spring so its tighter. Don;t worry,...there is more than enough torque to break the points open at the end of motor travel.
Try NOT to lift the armature out of the housing. If you DO...then you have to re-insert the spring in the correct slots for it to have proper pressure on the armature. IF the motor clicks after assembly when tested...there is a set of points too loose. Or the spring is not set right. Go Back.
Note the placement BEFORE disassembly.
Firstly, thanks Hooked for the link to the schematic. That was great. Thanks.

Lee, good explanation. The big spring on the armature fits in the slot. Its almost self aligning. You just need some tension from the **** side to the other side as you press it in. That took 3 tries to get it right. It makes it so much easier to get in when the spring is compressed a little. :-) I have to take it back apart. I sanded the points, reassembled and now it doesnt work in either direction. Did you unscrew that tiny phillips head screw and pull the whole board out and file the points when they were out of the housing and you could get good access to it? Or did you sand it while the board and points were in the housing? I tried to pry the board out and it wasnt cooperating so I sanded while in the housing.

Can you let me know about pulling the board out? I probably missed a second screw.

Thanks again guys for the info.

Tim
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Old May 12, 2011 | 12:05 PM
  #5  
86speeddemon's Avatar
86speeddemon
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Default Thanks

Thanks for all the help. I adjusted the points and the motor is working fine. The spring is the key to makeing the headlight motor work correctly.
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Old Nov 22, 2014 | 04:43 PM
  #6  
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ghr4news
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Default Problem with headlight door

Lee, I too am having a problem with my passenger side door. Before I start dismantling the door, motor, etc., can I do what you describe while the door and the motor are still attached to the car, or do I have to remove the headlight door and motor?

Thanks,
George

Originally Posted by leesvet
I just did this dance on an 87....same motors.
If the relays are good, the cycling problem is internal with the limit switches. There are 2...for each direction. One side is worn and breaking contact not sending power to the motor, so the system thinks its supposed to stay closed and will try to close if you open it manually with the ****...
You have to unplug the motor in this case to manually open, then simply plug it in to close.

Open the motor up, look at the contact breaker points on either side of the armature, opposite side of the gear box and see which is loose or soft or just dirty & corroded or worn.. The contacts need a good amount of spring tension against them so they do not try to open too early. I fought this for over a week and must have pulled that motor apart 10 times until I finally figured out the spring tension is the key. As the motor hits the end of its travel, the armature torques up and binds, slides one way or the other to open the points, stopping the power. Loose points open the instant the motor tries to turn stopping it before it moves, or never allows it to move/open. File the points and bend the spring so its tighter. Don;t worry,...there is more than enough torque to break the points open at the end of motor travel.
Try NOT to lift the armature out of the housing. If you DO...then you have to re-insert the spring in the correct slots for it to have proper pressure on the armature. IF the motor clicks after assembly when tested...there is a set of points too loose. Or the spring is not set right. Go Back.
Note the placement BEFORE disassembly.
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