First Generation Headlight Door Motors

Warning: Always unplug the headlight motors or disconnect the battery before doing any work on this system! The First Generation motors are energized at all times.

As noted in the Gen 2 HL motor article, I would never recommend people fix the First Generation system unless it is the only choice or required for showing in factory classes. The purpose of this article is to give you a general idea of how the Gen 1 system works and why it breaks down. It isn't meant to be a complete guide.

How does it work?

If you want pictures of the motor, have a read of this forum thread: Generation I headlight motor disassembly and Version 2.0. That thread will show you how much stuff is inside one of these motors.

The electrical diagram only tells part of the tail and many people make the assumption that all problems in the system are because one or more relays have failed. The relays are only a small part of what goes wrong with the old system.

As you look at the diagram, notice the switches in the motors. Those are mechanical torque operated limit switches and are what cause many of the mechanical and electrical problems in the systems. If these switches don't work perfectly every time, and they often don't, you can burn up the motors and/or relays, kill the battery, and a few other things. Problems with the torque switches are also part of what makes the gears break. Even when the limit switches work, their response time is lower and load spikes on the gears correspondingly higher.

How do the limit switches work?

There is a "cam" (Two actually) for lack of a better term that is connected directly to the armature shaft inside the motor. When the armature loads up beyond a certain point, one of the cams will shift and open the switch for whichever direction the motor was spinning.

But the armature is spinning and the cam moves up or down. How does that work?

The armature is tipped with a worm gear that drives the lift gears in the "bottom" of the motor. (Could be the top of the motor in some cars with this system.) When the lift gears bind up, the worm gear climbs up/down the lift gear. That action will force one of the cams to against its switch spring and when load is high enough to over come the switch, the motor shuts off.

This bit is very important... These limit switches are the only things that kill power in the system. The headlight switch always leaves either the open or close section of the circuit energized. This is a significant safety problem and why you need to unplug the motors or disconnect the battery when working on or around them, especially when clearing jams.

It Broke...

Well of course it did. This system wasn't all that reliable when it was built. 20 odd years later it is bound to screw itself up. There are various notes about this in the forums but I'll give you an overview of the potential breakage points.

The motors won't shut off.

They twitch/kick every few seconds to a couple minutes...

This likely is caused by one of thee things or it could be all these things at once.

The limit switches cut off but there isn't enough lockup friction in the gearing to hold them. The armature slips and each time it does, the motor kicks on.
The motor never activates the limit switch. When that happens, the motor won't cut out until a thermal circuit breaker inside the thing trips. When the breaker cools, the motor turns on and cooks until the breaker trips again.
A relay is sticking and tripping the thermal breaker in the motor. Same result as #2.

They keep spinning...

The gears are stripped.

The gears broke.

They are going to do this eventually even if the system works perfectly. Replacing them with metal gears may prevent broken gears but you still have to make sure the rest of the system is working right. The gears often don't break just from simple age. They are under high load at all times. They are actually under more strain when the system is "off" than when the motors are moving due to how the limit switch mechanism works.

The relay died.

That's fine but make sure the motors are shutting off properly or you'll probably fry the new one. The relay will fail from simple aging but a motor with a problem will accelerate burning up.

They won't run in one or both directions.

Could be a relay or broken headlight switch. If only one side, look at the motor and relays that affect that side.

Can the Gen 1 system ever be reliable?

To a point but it depends how much effort and money you want to throw at it. The hardest part will be getting the motors to trip the limit switches reliably. This is almost certainly going to require a very careful overhaul of the motors.

The problem is that there are so many parts in the system. The more parts you have, especially moving parts, the more likely it is you will have trouble. If you are patient and careful, the Gen 1 system can be made fairly stable. If you are going to show the car in a factory class, you will need to fix this system or you could lose points.

How does Gen 1 compare to Gen 2?

The Gen 2 motor is much more durable and simple to work on if it does break. The moving part count in the motors is significantly reduced and the motor controls eliminate mechanical torque switches. Also this system will shut down a motor completely if the doors/lifts jam anywhere between open and shut. Once the Gen 2 controller shuts a motor off, it stays off until the HL switch is cycled.

The Gen 1 system may shut down or not when jammed... Even if it shuts down, it can move without warning if the load on them changes. It can move regardless of HL switch position as the old system's relays and switches are never de-energized. For example: If you have an Ice jam, this system will move the second the ice shifts for any reason. If your hand is in the way, it will try to shut on you. The Gen 2 system won't even try to move until you operate the HL switch on the dash.

People who have had both systems indicate that the Gen 2 system is a little faster and noticeably quieter than the Gen 1 system. (I've dealt with both systems but haven't had them side-by-side.)

Upgrade Note are in Gen 2 HL motors.

Is converting really worth it?

Yes. It is the first alteration I'd make to any car that has this nasty mess, especially if there is the smallest thing wrong with it. Why? Depending what is wrong, fixing the Gen 1 system can cost as much or more than buying all the Gen 2 parts brand new. It can take way more time than converting. As you can often find used Gen 2 parts fairly cheap, it doesn't make sense to fix the Gen 1 system if you don't have to.