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Pedal Smasher
1973 Opel GT
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Discussion Starter · #1 ·
I've been working on the wiring diagrams from the '71, '72, and '73 FSM, as I try to do some long term planning for my electrical system. I'll eventually make my own wiring harness, so I need to know where every wire goes. I'm pretty sure I found some mistakes in the diagrams and I tried searching to see if this has been discussed before but I didn't find anything.

The mistakes have to do with the turn signal wires and what they connect to. The first mistake I found was when I looked at the color schematic and compared it to the turn signal and hazard flasher diagram, where the wires are located in the black steering column connector didn't match. The mistake here is the black / green and black / white wires got switched between the two diagrams. This happened in each of the FSMs I have for 71-73.
Schematic Rectangle Font Engineering Parallel
Product Schematic Rectangle Font Material property


Related to this mistake, I believe the diagrams are incorrect on where the wires connect for the dash indicator lights. The right blinkers / indicators use a black / green wire and the left blinkers / indicators use a black / white wire. But when I look at the dash indicators, the black / green wire connects to the bulb for the left turn signal indicator and the black / white wire connects to the bulb for the right turn signal indicator. That doesn't make sense to me, so I'm pretty sure they mixed that up.
White Product Schematic Font Line
Schematic Rectangle Font Engineering Parallel
 

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I've been doing some work in this area and failed to notice this discrepancy, but you are correct, at least with respect to the 1973 FSM. Not only is the color schematic wrong, but the error carries over to the breakout schematic on page 1J-78. I think the problem is nothing more than the trapezoid for the indicator lamps is mislabeled. The wire colors are consistent from the lamps through the triple connections on the fuse box labeled "R" and "L", up to the connections on the turn signal switch.
 

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GT Owner
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I've been working on the wiring diagrams from the '71, '72, and '73 FSM, as I try to do some long term planning for my electrical system. I'll eventually make my own wiring harness, so I need to know where every wire goes. I'm pretty sure I found some mistakes in the diagrams and I tried searching to see if this has been discussed before but I didn't find anything.

The mistakes have to do with the turn signal wires and what they connect to. The first mistake I found was when I looked at the color schematic and compared it to the turn signal and hazard flasher diagram, where the wires are located in the black steering column connector didn't match. The mistake here is the black / green and black / white wires got switched between the two diagrams. This happened in each of the FSMs I have for 71-73.
View attachment 446364 View attachment 446363

Related to this mistake, I believe the diagrams are incorrect on where the wires connect for the dash indicator lights. The right blinkers / indicators use a black / green wire and the left blinkers / indicators use a black / white wire. But when I look at the dash indicators, the black / green wire connects to the bulb for the left turn signal indicator and the black / white wire connects to the bulb for the right turn signal indicator. That doesn't make sense to me, so I'm pretty sure they mixed that up.
View attachment 446368 View attachment 446369
You need to use the Destec wiring drawings which have many corrections to the FSM.
 

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Pedal Smasher
1973 Opel GT
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3,350 Posts
Discussion Starter · #4 ·
You need to use the Destec wiring drawings which have many corrections to the FSM.
I might have them, but the computer that has my entire digital Opel GT library is down until September sadly. I know I have several PDFs with electrical diagrams. I have a laminated one from eBay, says classiccarwiring.com on it but it's not as good as the FSM one. I have a feeling I have a PDF that shows everything very well, but I can't access it and I'm not sure where I found it online either. There are a handful of things I'll be posting online when I get my computer running again, info too valuable to lose.
 

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GT Owner
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I might have them, but the computer that has my entire digital Opel GT library is down until September sadly. I know I have several PDFs with electrical diagrams. I have a laminated one from eBay, says classiccarwiring.com on it but it's not as good as the FSM one. I have a feeling I have a PDF that shows everything very well, but I can't access it and I'm not sure where I found it online either. There are a handful of things I'll be posting online when I get my computer running again, info too valuable to lose.
I can ship one to you on Friday. When September arrives ; you can ship it back to me.
 

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Pedal Smasher
1973 Opel GT
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Discussion Starter · #6 · (Edited)
I doubt this wiring diagram can be purchased anymore. I'd like to scan it and upload a copy for others, but it was made by a former Opeler. I found his email, supposedly, so I'm going to reach out to him.

edit Gmail kicked back a delivery failure notice, so the email I found for him is no longer active. Does anyone know how to contact him?
 

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I doubt this wiring diagram can be purchased anymore. I'd like to scan it and upload a copy for others, but it was made by a former Opeler. I found his email, supposedly, so I'm going to reach out to him.
I hope I’m wrong but I think he passed.
 
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I doubt this wiring diagram can be purchased anymore. I'd like to scan it and upload a copy for others, but it was made by a former Opeler. I found his email, supposedly, so I'm going to reach out to him.

edit Gmail kicked back a delivery failure notice, so the email I found for him is no longer active. Does anyone know how to contact him?
I hope I’m wrong but I think he passed.
If you mean JJ Wheatly, aka DESTEC Engineering who created the very excellent wiring diagrams, he passed away May 8, 2017

(Forum members we have lost (RIP))
 
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Pedal Smasher
1973 Opel GT
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Discussion Starter · #10 ·
Then we should be okay to share his work online now. Can't exactly get his permission anymore and if his wiring diagrams are that amazing, it's only right to keep his work living on in the community. I know that's what I would want if I produced anything that was immediately helpful to everyone who used it. Come to think of it, I do have at least one file I need to revise, share again and sticky.
 

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Opel Key Master
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I don't know the legalities of making blatant copies of his diagram. I have discussed this with several people, actually asked JJ fro the rights, but never a response (and he was still active). Gil told me he wanted in the neighborhood of $10,000 for the rights, and he wasn't interested. I many times want to copy it and just give it away with a harness and such. But again, I'm no lawyer, and yes if I made a copy I'm not selling it, so I do not profit from it. But the copyright laws may say even making a copy and distributing it is unlawful. I have some copyright with my air conditioning kits, and would like to keep it that way. I would say his family still owns the rights to that material, but don't know how to track it further
 

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1970 Opel Gt - Purchased July 1972 - Chartreuse - restored - 3000 miles as of 02-16, 2021 -
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Just a comment - I have no legal knowledge, but if he never pursued it and his family never pursued it most likely will never be pursued. However what I would love to see is a wiring diagram for the 1970 GT model year, in color and accurate. Unfortunately when I replaced my front headlight harness it turned out to be a later harness and the colors did not match up - and there were a few unused wires, not a good situation for a novice who hates electrical work.
 

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Opel Key Master
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The wiring diagrams are usually based on the 71-73 GT I have found. Truth be known, the 69 had some wiring differences and different components like the ignition switch had a power wire separate of the connector, the headlight wiring and marker lights are slightly different. Heater switch could have just one wire to the blower and controlled by a switch mounted resistor. If I recall I was having trouble years ago with a 70 that the ignition was slightly different, and I had to study the differences in the manual. The 70 manual diagram is terrible, but the 69 manual is even worse if you need a diagram for a Kadett Rallye, you will find it’s for a GT if I Recall
 

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I have mentioned this elsewhere, but the 1970 FSM has two diagrams for the GT, one purporting to be for an automatic-transmission car. It is dramatically different from the other diagram, particularly with respect to the headlamps. My guess is that the one indicating it to be for the automatic transmission is actually for European versions of the car
 

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Opel Key Master
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Not only that, it is horrible to read.
now Joe, on a separate note. JJ Wheatleys information isn’t the copyright, but his style and drawing is. What I mean is that he in many ways just copied the service manual and made it into full color, the artistic approach is copyrighted material, but the facts are not his. So I often thought of finding someone that could draw in a program for wiring harness diagrams to draw it upfor me. I’m not sure the program, maybe STEP or an advanced CAD flow(something). Been a while and not my forte.
 

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Pedal Smasher
1973 Opel GT
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3,350 Posts
Discussion Starter · #17 ·
Ya what program to use is the issue. I know it’s possible to do this in Microsoft Paint, but that would be a challenge. If there was money to be made, it wouldn’t be that bad.
 

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Ya what program to use is the issue. I know it’s possible to do this in Microsoft Paint, but that would be a challenge. If there was money to be made, it wouldn’t be that bad.
Visio? When building our house I installed lots of low voltage wiring and used Visio to create the as built diagrams. Pretty straightforward to use but if you need pictures of objects it would be a bit more work. It can import pictures IIRC.
 
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Would be pretty easy on AutoCad too. You can print different line widths based on color.
 
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