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Discussion Starter · #1 ·
I used the car a couple of nights ago and saw the headlights and side lights where on on the car when I was outside it but I could see nothing. I have identified it was only running on side lights. How do I get the main lights and main beam to work? Are they on a separate bulb??
Also are there any lights on the dashboard to light up the switches and/ or the heater controls?

Gary
 

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Just Some Dude in Jersey
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Hoo-boy, you've got lots of problems. The headlights will only come on when they are flipped up. There are microswitches in the mechanisms that close a circuit and make them come on. It is an unfused circuit and messing around with it can set your car on fire unless you do one thing: ALL new GT owners MUST verify that the wires going to the headlights have been replaced from where they split right/left at the radiator wall. Opel used vinyl wrapped wires JUST during the last 3 feet, thinking that the new fangled vinyl would last forever. It did not and the vinyl insulation turned literally to dust after only 10-15 years. This causes a massive short circuit that can melt your entire fuse box and catch the car on fire.

Before you do anything further you MUST unwrap those wires, WITH THE BATTERY DISCONNECTED, and verify that those wires going to the headlights have been replaced.

Here is the electrical schematic for the headlights:

Schematic Handwriting Font Engineering Parallel


Now, I do a mod where I make the headlights come on along with the Parking lights. Flick the Parking lights switch and both the Headlights and the Park lights come on at the same time. This way I can drive with the headlights up, but not on. You still need to check your headlight wiring and you should install a 30A inline fuse in both the high and low beam wires coming from the fuse box to the headlights. This mod is handy if you have faulty microswitches and don't have the time or skills to take the headlights all apart and go nuclear fixing everything. Here's a schematic showing how to do that:

Handwriting Font Schematic Parallel Engineering


Now, a number of folks here don't like that I do this mod and you should always go nuclear and repair everything. I did it because for decades I had GTs that had headlights that you couldn't flip, so I needed to do something to make them work. You may or may not have that same problem, I'm just showing you this mod as a quick fix.

The instrument lights and lame illumination lights are on a separate dimmer switch in the dash. Most of your bulbs are probably burned out or dim. The dimmer is called the "panel light rheostat" and is in the center of the first pick above. The gray/green wire that powers it runs through the yellow connector on the fuse box. Herein lies where many of your potential electrical problem are. The plastic of those connectors has shrunk and they don't plug in securely, plus the terminals have corroded. If you try pressing them in to make better contact the connector on the fuse box gets dislodged and pushes inwards. BE CAREFUL. You can try unplugging the connectors and spraying electrical contact cleaner at the terminals. But first try flicking the instrument light dimmer switch down and jiggling/pressing at that yellow connector to see if the lights flicker.

Electrical problems on our now 50+ year old GT's are a major problem. Many, many, GT's have been jury rigged by previous owners. Unfortunately, before you can start enjoying your car you're going to have to fix a lot of those things.
 

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The Young One
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Hoo-boy, you've got lots of problems. The headlights will only come on when they are flipped up. There are microswitches in the mechanisms that close a circuit and make them come on. It is an unfused circuit and messing around with it can set your car on fire unless you do one thing: ALL new GT owners MUST verify that the wires going to the headlights have been replaced from where they split right/left at the radiator wall. Opel used vinyl wrapped wires JUST during the last 3 feet, thinking that the new fangled vinyl would last forever. It did not and the vinyl insulation turned literally to dust after only 10-15 years. This causes a massive short circuit that can melt your entire fuse box and catch the car on fire.

Before you do anything further you MUST unwrap those wires, WITH THE BATTERY DISCONNECTED, and verify that those wires going to the headlights have been replaced.

Here is the electrical schematic for the headlights:

View attachment 440994

Now, I do a mod where I make the headlights come on along with the Parking lights. Flick the Parking lights switch and both the Headlights and the Park lights come on at the same time. This way I can drive with the headlights up, but not on. You still need to check your headlight wiring and you should install a 30A inline fuse in both the high and low beam wires coming from the fuse box to the headlights. This mod is handy if you have faulty microswitches and don't have the time or skills to take the headlights all apart and go nuclear fixing everything. Here's a schematic showing how to do that:

View attachment 440995

Now, a number of folks here don't like that I do this mod and you should always go nuclear and repair everything. I did it because for decades I had GTs that had headlights that you couldn't flip, so I needed to do something to make them work. You may or may not have that same problem, I'm just showing you this mod as a quick fix.

The instrument lights and lame illumination lights are on a separate dimmer switch in the dash. Most of your bulbs are probably burned out or dim. The dimmer is called the "panel light rheostat" and is in the center of the first pick above. The gray/green wire that powers it runs through the yellow connector on the fuse box. Herein lies where many of your potential electrical problem are. The plastic of those connectors has shrunk and they don't plug in securely, plus the terminals have corroded. If you try pressing them in to make better contact the connector on the fuse box gets dislodged and pushes inwards. BE CAREFUL. You can try unplugging the connectors and spraying electrical contact cleaner at the terminals. But first try flicking the instrument light dimmer switch down and jiggling/pressing at that yellow connector to see if the lights flicker.

Electrical problems on our now 50+ year old GT's are a major problem. Many, many, GT's have been jury rigged by previous owners. Unfortunately, before you can start enjoying your car you're going to have to fix a lot of those things.
I will have to use this info for my GT too. This is great info. Thanks a lot!
 

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Take this one slow. As explained above, first ascertain that the headlamp wiring is in good condition.

What year is your car. It gets complicated if 1969-70 because the circuitry for the headlamps and the white indicator lamp on the dash changed after 1970.

It gets even more complicated if 1969-70 because the two available wiring diagrams in the 1970 Factory Shop Manual do not "tie" (accounting term). That is, the circuitry shown for the GT with manual transmission is different than that shown for automatic (I found this out for myself helping Carl Hook with his headlamp problems).

By all means, get wring diagrams. My car, a 1971 GT, has quite a bit of 1969 internals and wiring, but was re-wired by a previous owner using post-1970 circuitry (except for the heater blower).

Yes, the headlamps only go on when the headlamp doors are opened, using that knife-like lever inside the car. When the doors lock into place, the headlamps should illuminate. When the doors are not locked, either fully open or fully closed, the white indicator lamp between the speedometer and tachometer should illuminate.

Looking at the instrument panel, you have six rocker switches. On the far left, there should be one with the European symbol for a lamp -- that will turn on the parking and side marker lamps. Tot the right of that is a blank, and to the right of that, next to the cigar lighter, is another rocker switch that dims and brightens the instrument panel lamps.

The headlamps operate with two special relays. One controls power to the headlamps while the other operates the high-low beam function.

The headlamps only operate with the ignition key in the "on" position.

Keep posting what you find or do not find.
 

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Your Noble Friend ;-)
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Hoo-boy, you've got lots of problems. The headlights will only come on when they are flipped up. There are microswitches in the mechanisms that close a circuit and make them come on. It is an unfused circuit and messing around with it can set your car on fire unless you do one thing: ALL new GT owners MUST verify that the wires going to the headlights have been replaced from where they split right/left at the radiator wall. Opel used vinyl wrapped wires JUST during the last 3 feet, thinking that the new fangled vinyl would last forever. It did not and the vinyl insulation turned literally to dust after only 10-15 years. This causes a massive short circuit that can melt your entire fuse box and catch the car on fire.
I don't know where "Gary GT" is located, but he has a Union Jack flag in his profile. If this is an European GT, it actually has a light switch in the interior. The lights don't come on automatically when you flip them up.

Dieter
 

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Discussion Starter · #6 ·
I don't know where "Gary GT" is located, but he has a Union Jack flag in his profile. If this is an European GT, it actually has a light switch in the interior. The lights don't come on automatically when you flip them up.

Dieter
Yes I am in the UK. I have a 1971 allegedly UK supplied 69,000 Miles from new which is a lovely car that is with the Automatic gearbox. My aim is to get all niggles fixed (that's my thing and what I get pleasure from doing). My lights where working prior to the other day (although that car hasn't been used for a few months). It does have a side light switch as well as a main light switch.

Gary
 

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Your Noble Friend ;-)
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Speedometer Vehicle Tachometer Gauge Car


Dieter
 
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I used the car a couple of nights ago and saw the headlights and side lights where on on the car when I was outside it but I could see nothing. I have identified it was only running on side lights. How do I get the main lights and main beam to work? Are they on a separate bulb??
Also are there any lights on the dashboard to light up the switches and/ or the heater controls?

Gary
So far, I perceive that you haven't been provided much for useful suggestions. Gordon (The SciFi Guy) has a pathological hatred of GT headlamps that is not shared by the general ownership.

Ir could be a bad terminal connection, or even bad wiring. The microswitch in the rotator is possibly at fault. If the running ("side") lights come on when the headlights are opened, then it seems the microswitch is working and energizing the relay. If so, it is likely simply a malfunctioning headlight relay. But the specific wiring in your GT may be different than what we are familiar with.

There were never any "UK" Opel GT's. So let us know if yours is a Euro GT (no rear side markers and a few other variances) or a North American GT. The serial # should also tell us. If it starts with a "77" , then it is a North American GT. A "79" would make it a Euro GT. The dash switches as Dieter has shown may also tell.

HTH
 
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