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Discussion Starter #1
Hello all,

I recently purchased a 1970 GT. Most everything on the car is in good working order, but I have some issues with the dash and wondering if there's a common denominator.

Let's begin with what works on the dash:

Dash lights
Battery gauge
Clock

What doesn't work:
Speedo (mechanical so not too big of a deal)
Tach
Oel gauge
Temp Gauge
Fuel Gauge
Blinkers or any other lights that are in the cluster above the steering wheel

Any insight would be greatly appreciated.

Thank you!

-Luke
 

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Can Opeler
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https://www.dropbox.com/s/3kh2bak2okmvpo5/17OpelGTElectricalSystemNotes.pdf?dl=0

You should review this entire document and check all the brown wires (grounds). It’s most likely a grounding issue, so start with finding and cleaning all the grounds.

Also if your clock is working you are a very lucky person. Most of us have never seen a working Opel Gt clock. I’ve fixed two Opel clocks, but I’ve never seen one that was working without repair.
 

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Discussion Starter #3
https://www.dropbox.com/s/3kh2bak2okmvpo5/17OpelGTElectricalSystemNotes.pdf?dl=0

You should review this entire document and check all the brown wires (grounds). It’s most likely a grounding issue, so start with finding and cleaning all the grounds.

Also if your clock is working you are a very lucky person. Most of us have never seen a working Opel Gt clock. I’ve fixed two Opel clocks, but I’ve never seen one that was working without repair.
Thank you for the reference doc. That's hilarious. The time on the clock was incorrect when I bought it so I figured it wasn't working. It wasn't until I was enjoying a late night beer sitting in the car in the garage that I wondered what the ticking noise was. Low and behold, the damn thing was working.
 

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Opeler
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If the dash lights are working, your ground is likely OK.

However, there is common supply of power to the dash, so you should check the fuse #2 from the left side. It is common fuse for brake lights as well, so if your brake lights are not working, you will know it is the fuse. In many cases it has just lost contact, so turn the fuse few times back and forth and you might regain contact.

If the fuse is OK, check for the lost contact at the black plug (black/red wire). Note, this is not black plug on the steering column but the one on the fuse box (located all the way to the left side).
 

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Check all of the fuses before you do anything else. There is a ground wire (brown) that attaches to one of the bolts that holds the steering column up. IfI remember correctly it is the ground to the speedometer casing. That is critical to all the other dash grounds. everything else is grounded to the speedometer casing.
 

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Just Some Dude in Jersey
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I did some extensive perusing of the electrical schematics, but could not find a common denominator. If your instrument panel lights work, that takes care of a whole lots of wires and grounds. I think pretty much the entire dash grounds at a wire to be found at the bottom of the steering column. I think it's black with a loop terminal on it and it gets attached to a bolt down there. It appears that your live-all-the-time(unswitched) power is there, but devices turned on my the ignition switch(switched power) are not.

Test every single dash and steering column switched device. Headlights - Hi and Lo, Park lights-do all of them light?, wipers, heater fan, stereo, flashers/turn signals, horn, lighter, etc.

Does the car start and run?


As a general rule on GT's, you always start at the fuse box. Obviously, check that none are blown, start the car and turn every single thing on, and spin the fuses in their holders to see if your non-working stuff comes to life. If that doesn't work, start pressing on the 6 colored multi-wire connectors plugged into the sides of the box. Carefull! Our 50 year old fuse boxes and the connectors are fragile as egg shells! Don't push too hard or the connectors will dislodge from the box and push inwards. Keep looking to see if any of your dead devices have come back to life. I've been able to fix most glitches this way.
 

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Discussion Starter #7
I did some extensive perusing of the electrical schematics, but could not find a common denominator. If your instrument panel lights work, that takes care of a whole lots of wires and grounds. I think pretty much the entire dash grounds at a wire to be found at the bottom of the steering column. I think it's black with a loop terminal on it and it gets attached to a bolt down there. It appears that your live-all-the-time(unswitched) power is there, but devices turned on my the ignition switch(switched power) are not.

Test every single dash and steering column switched device. Headlights - Hi and Lo, Park lights-do all of them light?, wipers, heater fan, stereo, flashers/turn signals, horn, lighter, etc.

Does the car start and run?


As a general rule on GT's, you always start at the fuse box. Obviously, check that none are blown, start the car and turn every single thing on, and spin the fuses in their holders to see if your non-working stuff comes to life. If that doesn't work, start pressing on the 6 colored multi-wire connectors plugged into the sides of the box. Carefull! Our 50 year old fuse boxes and the connectors are fragile as egg shells! Don't push too hard or the connectors will dislodge from the box and push inwards. Keep looking to see if any of your dead devices have come back to life. I've been able to fix most glitches this way.
Thank you. This is a wealth of information. I guess I should have mentioned that the wipers (including foot switch), hazard flashers, running lights, brake lights, headlights, heater fan and lighter all function. Horn does not. I was happy to see the hazards work so I know the run for them is good, but blinkers do not work from the column switch. The engine starts and runs just fine.

I'll dive in deeper and take your recommendations.

Greatly appreciated!
 

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Just Some Dude in Jersey
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This wiring breakdown page from the FSM appears to be specifically about your problems:

IMG_0582.jpg

Follow the path of the "BLK/RED" wire, it appears to supply power to all of the devices you're having problems with. Notice that it originates at the black connector on the side of the fuse box. Farther back, it comes from the second fuse from the right on the box and it appears to get it's power from the headlight relay. Check for loose wires. Kind of weird that the power doesn't originate at the fuse box, but, rather, it just uses the fuse box as a junction.

:veryhappy
 

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Discussion Starter #9
This wiring breakdown page from the FSM appears to be specifically about your problems:

View attachment 375369

Follow the path of the "BLK/RED" wire, it appears to supply power to all of the devices you're having problems with. Notice that it originates at the black connector on the side of the fuse box. It then goes to the second fuse from the right on the box and it appears to get it's power from the headlight relay. Check for loose wires.

:veryhappy
You're the man! I will update once I get under there and check it out!
 

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Discussion Starter #10
This wiring breakdown page from the FSM appears to be specifically about your problems:

View attachment 375369

Follow the path of the "BLK/RED" wire, it appears to supply power to all of the devices you're having problems with. Notice that it originates at the black connector on the side of the fuse box. Farther back, it comes from the second fuse from the right on the box and it appears to get it's power from the headlight relay. Check for loose wires. Kind of weird that the power doesn't originate at the fuse box, but, rather, it just uses the fuse box as a junction.

:veryhappy
There is a grey connector from the steerin column to the fuse block. Once I reseated that, everything came alive! All gauges and brights work, but the blinkers are still dead. So I assume that may be the relay.

Thank you so much!
 

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Just Some Dude in Jersey
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Great!

Okay, here's the page for your next problem:

IMG_0588.jpg

Sorry it's blurry. The turn signals and the flashers use the same relay, so if your flashers work, but your turn signals don't, then at least you know that the flasher relay is working. I think the turn signals, possibly the relay too, ground through the steering column somewhere. I don't have the time to dig through the schematic to help you out right now. Maybe others could suggest what to check.

Opel turn signals are very confusing because there's a German law thing that allows a turn signal lamp to stay lit but not flash when you are parked overnight.
 

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Can Opeler
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Great!

Okay, here's the page for your next problem:

View attachment 375407

Sorry it's blurry. The turn signals and the flashers use the same relay, so if your flashers work, but your turn signals don't, then at least you know that the flasher relay is working. I think the turn signals, possibly the relay too, ground through the steering column somewhere. I don't have the time to dig through the schematic to help you out right now. Maybe others could suggest what to check.

Opel turn signals are very confusing because there's a German law thing that allows a turn signal lamp to stay lit but not flash when you are parked overnight.
All of these pictures are scanned in that link I posted in the first reply if you have trouble reading this one.


Sent from my iPhone using Tapatalk
 

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Had similar issues with my 1972 GT rebuild - make sure the ignition switch is good

Hello all,



I recently purchased a 1970 GT. Most everything on the car is in good working order, but I have some issues with the dash and wondering if there's a common denominator.

Let's begin with what works on the dash:

Dash lights
Battery gauge
Clock

What doesn't work:
Speedo (mechanical so not too big of a deal)
Tach
Oel gauge
Temp Gauge
Fuel Gauge
Blinkers or any other lights that are in the cluster above the steering wheel

Any insight would be greatly appreciated.

Thank you!

-Luke
Hi There, just a quick note. If the fuse block is the heart of the GT electrical system which I agree with, the ignition switch is the jugular. I had similar issues with my rebuild, and when I replaced the ignition switch which is a very common failure area, it all started working. good luck. Andy
 
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