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One lazy headlight...

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Old Sep 20, 2017 | 04:51 PM
  #1  
gta_knight's Avatar
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From: England
Car: 1987 GTA
Engine: 350 TPI w/ extras !
Transmission: 700R4
One lazy headlight...

84 Trans Am, i thought it was possibly the motor at first so swapped in a replacement headlight unit which i knew 100% was working fine but it still acted the same.

turn the headlights on and the RH one comes up nicely, the LH comes up just behind it, no big deal, however if i turn the lights off, the RH one comes down no problem but 9 times out of 10 the LH stays up.

it takes a few goes of switching them on and off and it will at some point go back down. i took the switch out and cleaned it but it made no difference, i didnt think it would as it would be both lights acting up if it were the switch.

does each light have its own relay ? im wonder if theres a fault there perhaps
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Old Sep 20, 2017 | 06:12 PM
  #2  
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From: Modesto, California
Car: 88 Firebird Formula
Engine: LO5 5.7 TBI/Ebl Flash
Transmission: 700R4
Axle/Gears: 2.73 stock rear end
Re: One lazy headlight...

Originally Posted by gta_knight
84 Trans Am, i thought it was possibly the motor at first so swapped in a replacement headlight unit which i knew 100% was working fine but it still acted the same.

turn the headlights on and the RH one comes up nicely, the LH comes up just behind it, no big deal, however if i turn the lights off, the RH one comes down no problem but 9 times out of 10 the LH stays up.

it takes a few goes of switching them on and off and it will at some point go back down. i took the switch out and cleaned it but it made no difference, i didnt think it would as it would be both lights acting up if it were the switch.

does each light have its own relay ? im wonder if theres a fault there perhaps
Could just be the actual mechanical 'lever' getting stuck in the up position.
With hood open by hand you should be able to lock and unlock the lights in their up and down positions.
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Old Sep 20, 2017 | 06:41 PM
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From: PNW
Car: 91 Black Formula KR
Engine: 305 TPI R69/G92
Transmission: Astro A5-Pro 5.0-McCleod
Axle/Gears: US Gear 3.42 Eaton True Trac
Re: One lazy headlight...

There is a relay box on the firewall (under hood) near middle / driver's side that controls the pop up headlights... TDS sells refurbished boxes with warranties... also sells rebuild kits (I've used both from them and happy with both)...

Rafael
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Old Sep 20, 2017 | 08:49 PM
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Re: One lazy headlight...

Originally Posted by luvofjah
There is a relay box on the firewall (under hood) near middle / driver's side that controls the pop up headlights... TDS sells refurbished boxes with warranties... also sells rebuild kits (I've used both from them and happy with both)...

Rafael

The original poster's car is a 1984 , which did not use the electronic box on the firewall and instead had 3 relays and 4 limit switches controlling the motors (mounted in the general area of the headlights) . The relays are one "Isolation" relay and two "actuator" relays (one for each motor) and my wild azzed guess would be that either the actuator relay or the limit switch(es) on the affected light have bad (dirty) contacts that aren't making up electrically when they're supposed to .
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Old Sep 20, 2017 | 10:06 PM
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Re: One lazy headlight...

Check the relays first. Swap them left/right see if the problem follows the relay or the headlight assembly. The other issue I've seen is the internal connection of the headlight motors being weak. If you pop the side cover off the early motors, there's a connection between a brass tab and a wire. The tab is just crimped around the wire, and sometimes the connection breaks down over time. Cleaning the contact areas, and applying a dab of solder or even wrapping with a bit of stripped speaker wire is often enough to make the motors run 100% again.
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Old Sep 21, 2017 | 11:58 AM
  #6  
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From: PNW
Car: 91 Black Formula KR
Engine: 305 TPI R69/G92
Transmission: Astro A5-Pro 5.0-McCleod
Axle/Gears: US Gear 3.42 Eaton True Trac
Re: One lazy headlight...

My bad... I'll be the first to tell you I don't know everything
I have a 91... but thanks to the good resources and kind people (most of them) here on ThirdGen.org

Rafael
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Old Sep 23, 2017 | 07:19 AM
  #7  
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From: England
Car: 1987 GTA
Engine: 350 TPI w/ extras !
Transmission: 700R4
Re: One lazy headlight...

Thanks guys. There's similar shaped relays by the side of each fender so I assume they are for the lights. I will try swapping them over.

I don't think it will be the motor as I swapped the entire unit for a good spare one I had and it behaves exactly the same.

Where abouts is this isolation relay though?
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Old Sep 26, 2017 | 10:22 PM
  #8  
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From: Hacienda Heights, CA
Car: 90 RS 'Vert, 88 IROC-Z, 88 Firebird
Engine: 305 ci tbi, 305 ci tpi, 350 ci tpi
Transmission: WC-T5, WC-T5, 700R4
Axle/Gears: 3.45, 3.27, 3.27
Re: One lazy headlight...

Originally Posted by luvofjah
There is a relay box on the firewall (under hood) near middle / driver's side that controls the pop up headlights... TDS sells refurbished boxes with warranties... also sells rebuild kits (I've used both from them and happy with both)...

Rafael
He has a 1984 which used the 3-wire motors, headlight relays and isolation relays. You are referring to the headlight control module which was used starting in 1987 on the 2-wire headlight motors.

Lon
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Old Sep 26, 2017 | 10:23 PM
  #9  
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From: Hacienda Heights, CA
Car: 90 RS 'Vert, 88 IROC-Z, 88 Firebird
Engine: 305 ci tbi, 305 ci tpi, 350 ci tpi
Transmission: WC-T5, WC-T5, 700R4
Axle/Gears: 3.45, 3.27, 3.27
Re: One lazy headlight...

Originally Posted by OrangeBird
The original poster's car is a 1984 , which did not use the electronic box on the firewall and instead had 3 relays and 4 limit switches controlling the motors (mounted in the general area of the headlights) . The relays are one "Isolation" relay and two "actuator" relays (one for each motor) and my wild azzed guess would be that either the actuator relay or the limit switch(es) on the affected light have bad (dirty) contacts that aren't making up electrically when they're supposed to .
Agreed.

Lon
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