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Discussion Starter · #1 ·
Long story short, I had charging problems, and managed to make things worse by doing some "testing".

Now I finally have everything working fine, except my alt./low voltage warning light does not come on when it's supposed to. I have a feeling the bulb might have blown, so I want to check that. How big of a job is it to get access to the back of the gauge cluster? I don't think it can be done just by reaching up from the back, there doesn't seem to be much room.

I'd like to get it working again, but if it's a huge pain maybe I will just add a digital volt meter to the cockpit instead?

Thanks
 

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There are five(?) screws easily visible holding the instrument panel in place, plus a pair of cap screws that are access from either side of the dash -- one below the steering column and one on the passenger side. The passenger side screw is hidden by a removable button and you will need a socket with an extension to get to it. Not sure about the "standard", but on my GT I found the screw on the driver side more accessible by removing the triangular piece of trim attached to the heater duct above the driver's feet. Then you reach up and unscrew the cable from the back of the speedometer. Also, reach in the back on the driver's side and remove the turn signal flasher. After all of that, gently pull the instrument panel back into the cockpit. I do not remember exactly, but you may also have to drop the steering column to gain clearance -- this is four bolts holding it, and this could be a problem, in that the factory installed fasteners were not made to be removed and often had to be drilled out -- you may be fortunate in that this has been previously done and whoever did it replaced it with standard headed cap screws that will take a wrench.

Once you have pulled the instrument panel a few inches into the cockpit, the instruments and the lights you are looking for will be accessible.
 

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If you choose to remove, be VERY CAREFUL! That 50 year old plastic dash is easily cracked. Be gentle!
 

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Long story short, I had charging problems, and managed to make things worse by doing some "testing".

Now I finally have everything working fine, except my alt./low voltage warning light does not come on when it's supposed to. I have a feeling the bulb might have blown, so I want to check that. How big of a job is it to get access to the back of the gauge cluster? I don't think it can be done just by reaching up from the back, there doesn't seem to be much room.

I'd like to get it working again, but if it's a huge pain maybe I will just add a digital volt meter to the cockpit instead?

Thanks
Besides the accessibility, I got hung up on these:
  • "I had charging problems"
  • "Now I finally have everything working fine"
  • "my alt./low voltage warning light does not come on"

Please be aware that if that bulb is burnt out, your alternator will NOT get the needed trigger voltage (through the light bulb) to actually start charging. Measure your voltage on the battery, is it in the 13-14 Volt range (charging) or below 12V when the engine is running?

Dieter
 

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1970 Opel Gt - Purchased July 1972 - Chartreuse - restored - 3000 miles as of 02-16, 2021 -
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There are five(?) screws easily visible holding the instrument panel in place, plus a pair of cap screws that are access from either side of the dash -- one below the steering column and one on the passenger side. The passenger side screw is hidden by a removable button and you will need a socket with an extension to get to it. Not sure about the "standard", but on my GT I found the screw on the driver side more accessible by removing the triangular piece of trim attached to the heater duct above the driver's feet. Then you reach up and unscrew the cable from the back of the speedometer. Also, reach in the back on the driver's side and remove the turn signal flasher. After all of that, gently pull the instrument panel back into the cockpit. I do not remember exactly, but you may also have to drop the steering column to gain clearance -- this is four bolts holding it, and this could be a problem, in that the factory installed fasteners were not made to be removed and often had to be drilled out -- you may be fortunate in that this has been previously done and whoever did it replaced it with standard headed cap screws that will take a wrench.

Once you have pulled the instrument panel a few inches into the cockpit, the instruments and the lights you are looking for will be accessible.
Hey Michael, I am wondering about the 5 visible screws, as I can only find two, that are visible on the face of the instrument panel. See picture of the two screws that are visible, one to the left and one to the right of the radio. Perhaps I misread your post. This pictures is a 1970 GT. I am also not sure either about having to drop the steering column but in any event you would have to remove the collar from the steering column that rests against the instrument panel. There may be just enough room to reach in there to replace the bulb but I am not sure, pretty tight and also to Paul's point be careful as that instrument panel can in fact be very brittle after 50 years especially if it sat outside most of that time. Hope it can be done without dropping the steering column as I hate that job and have done it more times than I care to remember. But it will be a lot easier if you do infact drop the steering column. One other thought - the old original electrical wiring sometimes seems to me to have a mind of it's own - when messing with that wiring it is easy to bump something loose - could be just that - a loose wire. There is a good video on the forum by Knorm 65 - much easier to just watch -
Video: How to Remove Opel GT instrument Cluster, Heater, and Dash Pad

Good Luck.
434536
 

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Discussion Starter · #7 ·
Unfortunately I am 320 miles from the car at the moment, so I was writing from memory. For one reason or another, I thought there were five philips head screws. Maybe I lost count after the first...

But based on this pic, it would appear that there are six -- three across the top, three more just below the instruments.
I think maybe WIF is talking about a GT?
 

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Discussion Starter · #8 ·
Thanks everyone for the info so far. Unfortunately getting to that bulb sounds like a bigger job than I hoped for, or that I have patience for.

I just tried to check as much of the wiring for that bulb that is easily accessible. A diagram I have shows the wire for the warning bulb coming off the voltage reg.(D+) as having a fusible link, connected to a blue & white wire going to the dash. This wire has a little spade connector right near the VR plug. Is that correct?

Anyway for that wire I get + voltage only when the car is running. The connector and fusible link are ok, because I'm still getting + up to the wire where it splits off in the wiring harness that's covered (about 2' away from the connector). I'm a little confused on the path for the power going to the warning bulb. If this is the correct wire, it's only getting power when running, but the warning bulb is supposed to light when ignition switch is on, and go out when alternator is running. I get no warning light at all, neither when ignition is on and not running, or when it's running.

Dieter you have an interesting point. But according to my voltage tests, the battery is about 12.8 not running, and goes up to 13.8 when the car is running. Even with the lights turned on. This was not the case before I started fixing things a few days ago. I have checked this a few times.
 

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1970 Opel Gt - Purchased July 1972 - Chartreuse - restored - 3000 miles as of 02-16, 2021 -
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Thanks everyone for the info so far. Unfortunately getting to that bulb sounds like a bigger job than I hoped for, or that I have patience for.

I just tried to check as much of the wiring for that bulb that is easily accessible. A diagram I have shows the wire for the warning bulb coming off the voltage reg.(D+) as having a fusible link, connected to a blue & white wire going to the dash. This wire has a little spade connector right near the VR plug. Is that correct?

Anyway for that wire I get + voltage only when the car is running. The connector and fusible link are ok, because I'm still getting + up to the wire where it splits off in the wiring harness that's covered (about 2' away from the connector). I'm a little confused on the path for the power going to the warning bulb. If this is the correct wire, it's only getting power when running, but the warning bulb is supposed to light when ignition switch is on, and go out when alternator is running. I get no warning light at all, neither when ignition is on and not running, or when it's running.

Dieter you have an interesting point. But according to my voltage tests, the battery is about 12.8 not running, and goes up to 13.8 when the car is running. Even with the lights turned on. This was not the case before I started fixing things a few days ago. I have checked this a few times.
Sorry about that did not know we were talking about a Manta, my apologies.....anyway good luck
 

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Disconnect speedo-cable and remove screws & unplug gauge connector. Two screws at the top are covered by plugs that you pry off.
HTH
 
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