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Old 01-21-2004, 04:46 PM   #1
JAKE
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Default How to Test Headlight Door Motor?

1986 with a three wire plug to the headlight doors.

The passenger side won't raise but will close fine. I can open it by turning the **** manually and when I push the headlight switch to "off" the door closes. But it will not open on its own. So since the motor is reversible, it works in one direction but not the other.

I changed the isolation relay; didn't fix the problem.

I then disconnected the power connector to the passenger side headlight at the passenger side and tried connecting 12V directly to the plug leading to the motor, but could not get the motor to move no matter which combination of hot and ground I tried.

I've got three wires leading to the motor, dark green/white stripe, RED and the third one is black /white stripe.

Remember, the door will close but just won't open.

Can someone tell me how to connect 12 volts to the motor to check?

Any other options to check before I have to buy another headlight motor?

Thanks,

Jake
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Old 01-21-2004, 05:02 PM   #2
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Default Re: How to Test Headlight Door Motor? (JAKE)

Jake,
I want you to try something I did some years back.Make 2 jumper wires and cross them between the plug ins for the headlight motor at the harness.Dont apply an outside source of 12 volts to it,use the switch on the dash.
See if it switches the polarity when turning the lights on or off.

It also sounds like you may have a bad magnet in the motor.Mine were doing this years back and at the time,there wasnt any replacements available so I upgraded to the 88 and later headlights for a super cheap steal a friend at a GM parts place gave me it for.But anyways,I remember having the same symptoms but unsure if thats what it is for you though.

You may need to take the motor apart and see if the magnetic halves have shifted or broke loose from the sleeve.Some forum members got lucky and were able to glue or epoxy the magnet back inside the sleeve and that fixed the problem.
Mine broke apart and into alot of magnetic dust and I couldnt save them.
Besides,youll see if the gears or gear drive is stripped in any direction too.
HTH some.Its been a while but what I can remember.
:)

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Old 01-22-2004, 04:07 PM   #3
JAKE
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Default Re: How to Test Headlight Door Motor? (Bill's86Coupe)

Well, I tried all the things I could think of and still no results, so I took it off.

On the workbench, I was about to get it to run in the "close: direction, but only intermittently in the "open" direction.

There are three sets of contacts inside that are supposed to open or close depending on whether the headlight door is to open or close.

I fooled around with the motor for about 4 hours and finally realized the problem was something I didn't know how to (or luck up on) fix.

The gears and brushes are fine. Since electrical repairs are not really my cup of tea, this turns out to be one of those things best left to someone who knows what they're doing.

I'm going to send the motor to CorvetteCentral for a repair. $99.00 is the best price I could find; 1 year warranty.

Jake
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Old 01-22-2004, 04:36 PM   #4
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Default Re: How to Test Headlight Door Motor? (JAKE)

Hi Jake,
Thats not a bad idea or price either,not to mention the 1 year warranty either.
Were you able to determine if the magnets were good or cracked?Im just wondering since you didnt mention it.
Keep us posted how the new motor comes out.Im betting its an exchange service right?
:)
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Old 01-22-2004, 04:53 PM   #5
AimHi
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Default Re: How to Test Headlight Door Motor? (JAKE)

Jake,

The right headlight on my 95 had the exact same symptoms. It was getting old having to open the hood and open the headlamp by hand everytime I wanted to drive at night. I was ready to send it out for repair. Instead of doing that I opted to buy the bushings from Eclkers and put them in first to see if they would solve the problem. They did the trick.

Do a search of the archives for "bushing replacement" or "headlamp motor" and you'll get all the tips you need to be successful.

Good luck!

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Old 01-22-2004, 05:24 PM   #6
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Default Re: How to Test Headlight Door Motor? (AimHi)

Aim,
The 84-87 C4's have a different headlight motor system.They cant be fixed with bushings like the 88 and up C4s.
Just letting ya know.

:cheers:
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Old 01-22-2004, 06:29 PM   #7
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Default Re: How to Test Headlight Door Motor? (Bill's86Coupe)

Wow, thanks I had no idea! Learning as I go....
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Old 01-22-2004, 07:10 PM   #8
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Default Re: How to Test Headlight Door Motor? (JAKE)

Jake, i think you muffed something along the way

When a headlight goes one way but not the other, the relay is to blame
The odds of it being something other than the relay are about as good as that of winning the lottery.... maybe this is your lucky day? :lol:

Triple check everything before you send away for motor repair (actually, you can do it yourself... it's easy! i repaired mine without any instruction or special tools)

Take the relay from the right side and put it on the left side connection, and vice versa. See what happens. Maybe the new relay is faulty? :confused:


[Modified by Bilyk, 6:16 PM 1/22/2004]
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Old 01-22-2004, 07:16 PM   #9
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Default Re: How to Test Headlight Door Motor? (Bill's86Coupe)

Quote:
Aim,
The 84-87 C4's have a different headlight motor system.They cant be fixed with bushings like the 88 and up C4s.
There are no replacement bushings because the early motors don't havy any bushings to wear. I am not sure what corvette central charges 99 dollars for, but all the contact points are metal and don't wear out; the magnets can be reglued with JB weld; white grease and silicone is all you need to seal the case. The only item that wears or can break are the geras - replacements are available in both plastic and metal sets for less than $99
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Old 01-22-2004, 08:43 PM   #10
JAKE
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Default Re: How to Test Headlight Door Motor? (AimHi)

[QUOTE]Jake,

The right headlight on my 95 had the exact same symptoms. It was getting old having to open the hood and open the headlamp by hand everytime I wanted to drive at night. I was ready to send it out for repair. Instead of doing that I opted to buy the bushings from Eclkers and put them in first to see if they would solve the problem. They did the trick. [/SNIP]

Thanks, but the 86 doesn't have those bushings; I believe they began with the 88 model year. I checked that possibility out right away.

I had first thought of just buying two new gears, thinking those were probably the cause. Good thing I didn't because my gears are fine and the rebuild comes with new gears anyway.

My problem has to do with the contacts inside. If I manually close one of the three contacts, the motor runs in both directions, but a lot slower in the open direction.

Just call me "Blinky" for the time being.

Jake


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Old 01-22-2004, 09:01 PM   #11
JAKE
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Default Re: How to Test Headlight Door Motor? (Bilyk)

Quote:
Jake, i think you muffed something along the way

When a headlight goes one way but not the other, the relay is to blame
The odds of it being something other than the relay are about as good as that of winning the lottery.... maybe this is your lucky day? :lol:

Triple check everything before you send away for motor repair (actually, you can do it yourself... it's easy! i repaired mine without any instruction or special tools)

Take the relay from the right side and put it on the left side connection, and vice versa. See what happens. Maybe the new relay is faulty? :confused:


[Modified by Bilyk, 6:16 PM 1/22/2004]
I tried that first. I switched door relays from one side to the other. Same result. Driver's side would open, but passenger side wouldn't.

I ran the diagnostic tests shown in the GM Shop Manual and all the relay voltages checked as they should. I then ran the tests on the motor connector itself and all the voltages checked good there too.

If I manually open the passenger side by turning the **** (takes forever too), then push the headlight dash switch to "off" they both close normally.

I tried a new isolation relay; made no difference. Since closing of the passenger side door receives it's battery voltage through the Isolation Relay, I figured the new one is okay.

I'll try throwing two new door relays at the problem to see if that makes any difference.

If not, I'll send it off for repair. If repairing the headlight doesn't solve it, then I guess I'll just confine my driving to daylight hours.

Thanks,

Jake

T
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Old 01-22-2004, 11:17 PM   #12
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Default Re: How to Test Headlight Door Motor? (JAKE)

which contacts are we talking about here? inside the relay or inside the motor?

i really don't think it's the motor
there is nothing inside it that can cause it to spin one way and not the other... it's just a fancy DC motor... no electronics inside whatshowever

the only other thing i can think of is that something is catching maybe? any buzzing sounds from the right motor? any twitching? any gridning when you turn it manually?

this is REALLY bizarre

how about swapping the left/right motors themselves? the connector is the same on both sides so it should work
that way you know there is something wrong with the motor for sure before you send it off

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Old 01-23-2004, 01:50 PM   #13
JAKE
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Default Re: How to Test Headlight Door Motor? (Bilyk)

The contacts I was referring to are the three inside the motor housing. To of them were closed and the third open.

If I close the third one, the motor runs fine in closing direction, but in "fits and starts" in the opening direction.

There are a few solder points inside and they all seem to be solid.

The magnet, however, is in two pieces. Strange too is that seems like about 1/3rd of the space is empty. Let my try to explain: The magnet fits inside a round, metal sleeve (360 degrees), but the magnet doesn't cover the entire circumference of the sleeve. About 1/3rd is empty; no magnet. Picture a clock: there is magnet from 12:00 until 8:00, but NO magnet from 8:00 to 12:00.

I found No evidence that it ever contained magnet material - no filings, etc., so I'm assuming that's they way the motor is built.

When I energize the motor, tiny sparks come from the brushes, which I suppose is normal too. The brushes are about !/4" high.

I've never worked on electrical motors (other than to change one out and put in another one), so I'm pretty much lost. All the internals checks I've made (and I've had that sucka apart several times) were made in the hope of finding something obvious, like a loose wire, etc.

Jake
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Old 01-23-2004, 01:50 PM
 
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1986, 2001, close, corvette, door, exploded, headlamp, headlight, isolation, manually, motor, open, problem, relay, view


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