Help identifying these multi-plugs 77 GS750 - WIRING CHAOS

[Guest]

Hi folks,

This is my first post but I very much doubt it'll be my last.
I picked up my 77 GS750 here in the UK earlier this year and have slowly been restoring it.
When I started to pick apart the wiring loom I noticed a load of issues and bodges (every single wire has been cut and joined onto a different coloured wire multiple times which makes identifying anything impossible) so I made the decision to buy a replacement loom online that was un-cut.

I've been working my way through the new loom, labelling up various plugs and connectors when I came across two large multi plugs.
The first is a black 10 pin plug that sits near the headlight connectors / ignition switch etc.
The second is a grey 11 pin plug that sits down by the orange / black and white wires for the coils.

I believe the grey 11 pin plug connects to my LH switches but I have no idea where the black 10 pin goes as my old loom didn't have this plug.

The wire colours on the black plug are as follows:
Grey
Blue
Black
Orange
Yellow
Light green
Green with red tracer
Green with yellow tracer
Yellow with red tracer
Black with white tracer

Judging by the colours, I assume this plug is intended for the instrument cluster and is perhaps from a different model bike than mine. Either that or someone has butchered the wiring coming from my instrument cluster and has changed the connectors.
Looking at the wiring loom that came off the bike (the bodged one) these wires are connected to the cluster via 2 or 3 smaller connectors with 6 and 4 wires in each.
First one has Grey, Orange, Light green, Black, Green with yellow trace and black with white trace.
The second plug is a mess and has been frankensteined, joining different coloured wires to each other.


I appreciate this is a long and rambling post, I'm currently typing from my bedroom as I have to self isolate for 10 days and I cannot get to the bike to check it.
I've attached a couple of pics to help to clarify what I mean. The first three pics are the plugs in question from my new loom (1 pic of the grey one and 2 of the black one) and the last two pics will be the instrument cluster plugs from the old loom. Note that the wire colours on the last two images shouldn't be taken into consideration as they are spliced onto different coloured wires shortly after the connector under all of that lovely loom tape.

Many thanks in advance,
Tom.

 

[Guest]

Edit - I have no idea why the pics are so massive Sorry!
Might help identifying the issue I suppose.

 

[Brendan W]

These any help?
https://gsarchive.bwringer.com/storagecliff/images/750e-s-z_wiring.jpg
https://www.cmsnl.com/suzuki-gs750-1977-b-usa-e03_model34273/partslist/BLCK0078.html

 

[Rich82GS750TZ]

Welcome to the site.

I know the bike year and model are in the thread title, but please create a signature that includes that info. Go to Settings at the top of any page, you’ll figure it out from there. It’s always appreciated, and you’ll never have to write that info again, and no one will have to ask.

You can find a factory service manual on BikeCliff’s Website, linked in my signature. Top section, center column. there’s a wiring diagram near the back of the book. You want the GS 750 (8 valve)…..

On the same site, top section, right column, there are some really nice color wiring diagrams. None for your specific bike, but Suzuki was very consistent in wiring color/function between years and models, that you may find one of those to be helpful.

 

[Guest]

Thanks both,

I've edited my signature to include the bike model info.

I have a Haynes manual with wiring diagrams and I've spent a good few hours going over Bikecliff's website - however I can only see the one large multiplug for the LH switches, not the second one.
This is the same on any wiring diagram I look at. I've noticed on a couple of build threads on here that some bikes have the black connector in question so it must be on some of the diagrams, I just can't see it.

 

[Guest]

I've figured it out... I think.

I believe the existing wiring loom was from a GS750C, the loom I have bought is from a GS750B.
So I just need to find an instrument cluster from a 750B or wire it up so that it all works with the different loom.