Several headlight questions
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Melting Slicks
Joined: Sep 2000
Posts: 2,683
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Several headlight questions
'84 - '87 headlight motors are different than '88 - '96 motors, but what's the difference?
'88+ motors require an '88+ headlight actuator, correct?
Can '88+ motors be directly swapped onto '87- brackets?
I'm selling a pair of '88 motors but the member I'm selling to wants to put them on an '86 and I don't want to sell him something that he cannot use.
'88+ motors require an '88+ headlight actuator, correct?
Can '88+ motors be directly swapped onto '87- brackets?
I'm selling a pair of '88 motors but the member I'm selling to wants to put them on an '86 and I don't want to sell him something that he cannot use.
Pro
Joined: Jul 2002
Posts: 729
Likes: 4
From: Yukon OK
Re: Several headlight questions (A)
Pre 88 motors had some limit switches inside the motor housing that stopped the motor at the up and down positions. These motors had 3 wires coming out of them because they had to have a "up" signal and a "down" signal to drive the motor in each direction. Three relays controled the motors.
88 and up had a solid state module to control the motors. There were no limit switches in the motor so they only had 2 wires going directly to the brushes. The module detected the motor stall by a current sensor and shut the motor down.
To do a full conversion requires changing both headlight motors, replacing the relays with the electronic module and upgrading the wiring harness for all the new connections. The headlight assembly will fit without modification. It is the electrical system that changed.
88 and up had a solid state module to control the motors. There were no limit switches in the motor so they only had 2 wires going directly to the brushes. The module detected the motor stall by a current sensor and shut the motor down.
To do a full conversion requires changing both headlight motors, replacing the relays with the electronic module and upgrading the wiring harness for all the new connections. The headlight assembly will fit without modification. It is the electrical system that changed.
Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17
wiring kit
Pre 88 motors had some limit switches inside the motor housing that stopped the motor at the up and down positions. These motors had 3 wires coming out of them because they had to have a "up" signal and a "down" signal to drive the motor in each direction. Three relays controled the motors.
88 and up had a solid state module to control the motors. There were no limit switches in the motor so they only had 2 wires going directly to the brushes. The module detected the motor stall by a current sensor and shut the motor down.
To do a full conversion requires changing both headlight motors, replacing the relays with the electronic module and upgrading the wiring harness for all the new connections. The headlight assembly will fit without modification. It is the electrical system that changed.
88 and up had a solid state module to control the motors. There were no limit switches in the motor so they only had 2 wires going directly to the brushes. The module detected the motor stall by a current sensor and shut the motor down.
To do a full conversion requires changing both headlight motors, replacing the relays with the electronic module and upgrading the wiring harness for all the new connections. The headlight assembly will fit without modification. It is the electrical system that changed.
Pro
Joined: Jul 2002
Posts: 729
Likes: 4
From: Yukon OK
Feels weird to see one of my old posts pop back up. Yes there are kits available but if you want to do it on the cheap just pick up the head light assemblies used on ebay or at a Vette salvage yard. The module can be found at salvage yards. GM used the same module on all cars with headlights that lift up. I picked up a module for $5 at Pull-a-Part (also got a spare). The wiring is not all that difficult.
I have the wiring diagrams as .jpg files somewhere. Let me check and see if I can dig them up.
I have the wiring diagrams as .jpg files somewhere. Let me check and see if I can dig them up.
Pro
Joined: Jul 2002
Posts: 729
Likes: 4
From: Yukon OK
Found the info over in my Flickr account. I made a couple of drawings to simply things so you can see the difference between the two systems and also figure out how to convert to the newer headlights.
There are also some photos if you want to see the inside of the early C4 headlights.
http://www.flickr.com/photos/1757654...7602882678033/
BTW; in my old post I said you had to replace the motors and I should have said replace the entire motor and headlight frame assy.
Cheers
There are also some photos if you want to see the inside of the early C4 headlights.
http://www.flickr.com/photos/1757654...7602882678033/
BTW; in my old post I said you had to replace the motors and I should have said replace the entire motor and headlight frame assy.
Cheers
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Instructor
Joined: Jun 2010
Posts: 116
Likes: 2
From: Webster Florida
I picked up a set of headlight assy... Before I bought them I wanted to make sure they worked so the seller and I used a battery charger which allowed both to function.
Removing the old ones from my 85 corvette I noted that the ones on the car had 2 wires and the new ones had three wires. I can get them to work if I hit them with power from a external battery but not if I wire them to the car. I've got an 86 service manual so I looked up the wiring diagram. It shows relays... I looked everywhere... I have no relays and it's apparent that someone has done some homemade wiring. Might my car been converted to the newer headlight motors? how can I tell for sure and what do you think I need to do to get these new motors to work wired up to the car?
thanks in advance,
Robert
Removing the old ones from my 85 corvette I noted that the ones on the car had 2 wires and the new ones had three wires. I can get them to work if I hit them with power from a external battery but not if I wire them to the car. I've got an 86 service manual so I looked up the wiring diagram. It shows relays... I looked everywhere... I have no relays and it's apparent that someone has done some homemade wiring. Might my car been converted to the newer headlight motors? how can I tell for sure and what do you think I need to do to get these new motors to work wired up to the car?
thanks in advance,
Robert
Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17
I picked up a set of headlight assy... Before I bought them I wanted to make sure they worked so the seller and I used a battery charger which allowed both to function.
Removing the old ones from my 85 corvette I noted that the ones on the car had 2 wires and the new ones had three wires. I can get them to work if I hit them with power from a external battery but not if I wire them to the car. I've got an 86 service manual so I looked up the wiring diagram. It shows relays... I looked everywhere... I have no relays and it's apparent that someone has done some homemade wiring. Might my car been converted to the newer headlight motors? how can I tell for sure and what do you think I need to do to get these new motors to work wired up to the car?
thanks in advance,
Robert
Removing the old ones from my 85 corvette I noted that the ones on the car had 2 wires and the new ones had three wires. I can get them to work if I hit them with power from a external battery but not if I wire them to the car. I've got an 86 service manual so I looked up the wiring diagram. It shows relays... I looked everywhere... I have no relays and it's apparent that someone has done some homemade wiring. Might my car been converted to the newer headlight motors? how can I tell for sure and what do you think I need to do to get these new motors to work wired up to the car?
thanks in advance,
Robert
Instructor
Joined: Jun 2010
Posts: 116
Likes: 2
From: Webster Florida
so... if the motors have only two wires going to them they are 88 or newer motors and if three wire they are older... correct? My 86 Corvette headlight motors are two wire motors also... and they work perfect!
Pro
Joined: Jul 2002
Posts: 729
Likes: 4
From: Yukon OK
Is it possible your 86 was converted to the solid state control module rather than using the 3 relays?
Pro
Joined: Jul 2002
Posts: 729
Likes: 4
From: Yukon OK
Team Owner
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From: Fort Knox, KY
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