Opel GT Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter #1
Does anyone know a simple way to replace the main fuse block?
The original cover is missing and the block itself cracked in a rather unfortunate location.....the mounting points!
Basically I have the fuse block just hanging by the wires, and there is a tendency for some of the connections to loosen and cut out (namely the fuel pump), because it gets kicked occasionally.
I really don't want to have to cut the old wiring and splice in a new box considering the number of wires. I know it's going to be a pain, and all those splices will surely vibrate loose eventually.
Anyone have any ideas?
 

·
Super Moderator
Joined
·
13,581 Posts
You should identify what type of car you have first, since there are numerous types of Opels that could be afflicted with this problem.

Bob
 

·
Registered
Joined
·
69 Posts
I have the same problem on my '70 GT. The car came with an extra origional style fuse block, but it's just as bad as the one in the car now. I located two other potential fuse blocks, but one of them was just as bad too, and the other one was getting close to breaking any day. So, I've decided to use the origional fuse block from one of my chevette parts cars. It is going to be a pain like you said with having to cut and connect each wire to the new fuse block, but when it's all said an done, it should be a lot more reliable than the stocker. Plus the flat blade type fuses for the new block are so much easier to find than the origional GT fuses. It's just my opinion, but I'd say bite the bullet and replace the block with a newer style. I think you'll be a lot happier in the long run. :D

Best of luck,
John
 

·
Registered
Joined
·
16 Posts
Discussion Starter #4
I'm sorry i didn't list the model (i was rushing to get out of work)...It's a '71 GT. I think i'm going to have to take JOHNBRAN'S
suggestion and update it with an aftermarket fuseblock that will accept blade-type fuses. The old ceramic ones are getting extremely hard to come by. (i'm an electrical designer by trade so i kinda know that it's not going to "just" splice in...but i think it might be worth the trouble). Or...Do you guys (and girls) out there really think i should try to keep it stock? The rest of the car is far from being stock, so i don't really think this is an issue, at least not with me anyway. But, y'all know more than i, so i value your input.
 

·
Member
Joined
·
257 Posts
If it is far from being stock I would modify, customize and update everything and anything. Let me know how the fuse box goes, I may want to do the same.

Stanley
 

·
Registered
Joined
·
69 Posts
Right now I am in the process of making a wiring diagram of the two boxes first. This is so that when I actually tear into it, I should be able to pretty much just remove the wires, solder on the proper connectors and hook the wires into their appropriate holes. So far, it looks like a pretty straight forward swap. The main thing that I figure could cause a little problem is making sure that the new fuse block has the correct amperage fuses installed for the GT circuits. So far, several of them are much different on the GT than they are on the Chevette block. This isn't a really big deal to correct, but that is why I think making up a diagram before hand is a good idea so you can already have the new block fitted with the correct fuses before starting the change. I'm using a used OEM fuse block from an '83 Chevette, but it would still be a good idea to make up a diagram even if you went with a new aftermarket fuse block. It would not be fun if you went to all that trouble and fried half your wiring due to a misplaced or overamp fuse.
:(
I've got another idea for upgrading the electrics as well. Because the GT has seperate switches for the headlights, dash lights, and running lights, I am considering doing away with the flip lever switch for the headlights and installing a standard headlight switch and completely new wiring for the headlights. This could possibly prevent future problems with the GT wiring (fire?) and the origional style switch on the headlight flip lever which I have heard can be a problem on these cars. The lever would still be used to flip the lights over, but they would be turned on by the new switch. Since my car does not have the rear window defroster, I was considering using the switch for the rear defroster to turn the headlights on and off so I do not have to cut up the dash for a new headlight switch, but I do not know if the switch can handle the power load of the headlights yet. I haven't seen anything else that would really prevent this change, but if anyone out there with a good understanding of the GT wiring setup can think of any problems this might cause, please let me know so I don't risk damaging something. Also, if any of you know whether or not the rear window defrost switch would be able to handle the power load of the headlights, I'd appreciate the info as well.
I'll keep this post updated as I get more into this upgrade. Best of luck if you decide to swap yours out!!

John
 

·
Super Moderator
Joined
·
1,798 Posts
Fuse box

The fuse box from an Audi 5000 is a through the firewall design. It's wires hook up on one side, and the fuses and relays for the car on the other. It uses commonly available relays and blade type fuses, and is about the same width as the stock GT fuse block. If the (probably broken) plastic box for the relays and fuses in the GT is removed, it is very easy to fabricate a small "L" of sheet metal to hold the fuse box in it's place with the fuses and relays easy to get to.

The truely great part of using an Audi or VW fuse box is the ease of wiring. Circuits designated as "15" on the Opel need to hook-up to terminals designated "15" on the fuse box. (That's what the #'s on the lights and switches are for.) Further, the fuse box terminals are all easy to use 1/4" male plugs, available anywhere.

While it took me @2 hours to verify all the terminals on the fuse box, it only took another 2 hours to rewire an entire Kadett end to end using the Audi fuse box. That for @ $150 less than the painless wiring harness. The fuse box also had provisions for the electric fuel pump, stereo, rear window defroster, power windows, and 6-8 other functions like heated power seats I haven't used yet.
 

·
Super Moderator
Joined
·
1,798 Posts
Early to mid 80's Audi 5000's are great.

Late 80's Volvos have a neat set-up too.
 

·
Super Moderator
Joined
·
1,798 Posts
defroster switch

The defroster switch will most definatly NOT handle the power of the headlights. Even for the defroster it needed a relay to handle the amperage.
It shouldn't be too much of an issue to use the stock GT headlight relay and replace only the microswitches with the defroster switch if you wanted. I'll look through the wiring diagram and see if I can't point you in the right direction.

I'd use the fog light switch myself, since everyone trys to use it for headlights anyway, but to each his own.
 

·
Registered
Joined
·
69 Posts
I hadn't thought about using the fog light switch. I assume that since it is already being used for lights, it would probably handle the load of the headlights? I really didn't figure that the rear defroster switch would work, but I was just trying to think of something to use that wouldn't require me cutting holes in the dash. Would you happen to know what, if any, mods would have to be done to the fog light switch? Does it have it's own relays? Do you think this upgrade would be worth attempting in the first place? The biggest reason I am even considering it is due to the "horror stories" I've read about people almost bashing up their GT's due to the lights going out at really unhandy times. Doesn't sound like something I'd want to chance happening, so I'm just wanting to build in a little safety measure into this area of the car.

Thanks,
John
 

·
Super Moderator
Joined
·
1,798 Posts
swithes and relays and wires

Any switch on the dash of the Opel needs a relay to handle the power of the headlights. Period.

There is already a capable relay in place, it uses the signal from the rollover microswitches to activate it, and it then supplies power to the headlights. The easy thing to do would be to change the input signal to this already existing relay to the foglight switch instead of the microswitches.

The reason the GT uses the miroswitches is so the headlights can't come on in "down" and overheat themselves. I've personally never seen a GT have problems with failed microswitches causing the lights to go out. Then again, I don't usually work on GT's and I've probably only worked on 10-15 of them.

The reason GT's usually have problems with the headlights is due to the wires themselves. There are 3 wires going to the headlight of an Opel, white and yellow for high and low beam, and a color I can't remember for the ground (probably brown.) Because of the flexibility requirements necessary for the flip over headlights, the factory equipped the car with wires that were insulated with ruber instead of PVC like most wires on the car.

Have you ever seen a 30 year old tire that you would want to use?

EVERY GT needs to have these rubber wires replaced. Yes, all of them. It can be a real pain in the arse, but you have to do it. Once the wires are replaced, there is a couple of quick adjustments to make sure linkages all line-up, and making sure to lube the cable thoroughly, and the headlight system is relativly trouble-free. One of the downloads available here, in fact, is a pretty darn good "article" on maintaining the headlights that every GT owner should read.

About the wires. There are 2 types of wiring commonly available to the consumer these days. One is insulated with PVC, and the other with teflon. The PVC wires run on the order of 4-15 cents a foot, and the teflon for around $2 a foot. For your GT's headlights you really want the Teflon, if at all possible. Luckaly, almost every automaker switched in the early 90's to teflon insulated wires (easily identifiable by the insulation being almost 1/4 as thick) so you can save some $ wth a good pair of snips at the local junk yard. Get the headlight wiring from a Honda and you can leave the ends on the wires where they connect to the bulbs and use them too. Once the wiring is replaced, the headlight system on the GT is not any more "dangerous" than any other auto.
 

·
Super Moderator
Joined
·
5,804 Posts
Headlight Wiring and other Hot Topics

Even if you replace the headlight wiring (and it IS a MUST for ALL GT's, right back to the harness connections within the main loom!!), you should also incorporate a fuse or circuit breaker in the headlight wiring power supply (rather than the relay supply). I believe that a 30 amp fuse will do, but I have read that a 35 amp breaker is required to prevent it from tripping prematurely, especially with higher wattage aftermarket bulbs. Or even install one fuse/breaker per side, to give you a "limp-home" feature.

For wiring diagrams to use your parking light switch to activate the existing relay, and various other "must read" articles on GT headlights (including one by yours truly), surf to the Classicopels Yahoo site, specifically to

http://groups.yahoo.com/group/classicopels/files/ Technical Information/Headlights/

The article on bypassing the microswitches is the top one, by Gordane (GT light wire fix and diagrams.html ) and his wiring schematics are the bottom four .gif files

HTH.
 

·
Registered
Joined
·
69 Posts
Thanks for the link Keith!! And thanks for the info on the relays, wires, and wire differences oldopelguy!! Both of these has helped a lot! :D

John
 
1 - 14 of 14 Posts
Top