R100GS main loom versions

[robertotoole]

Does anyone know the difference between the loom for the 93 onwards GSPD and the pre-93 loom? - other than the later one costing £200 more!
I know that the indicator relay on that later loom is what seems to be a non-standard expensive BMW relay. Anything else? Can I easily adapt my wiring to work with the earlier version? My wiring is looking very bad. Yesterday one of the wires connecting the ignition switch into the loom broke. I could see that the wiring is brittle and corroded in places.

Thanks

 

[robertotoole]

I mean pre-90 loom, not 93.

 

[Gelandestrasse]

Where do we start here....? There are many differences. 3-fuse box on pre-91 models; post-91 have 4 fuses. No outlet for heated grips pre-91. Pre-91 the flasher unit has 3 cables to it; post-91 there are 10 connections. No load-shedder pre-91. Not to mention all the bespoke connectors between the 2 models.

Anything is possible, but making a pre-91 loom fit a post-91 bike you will end up with a loom so chopped about and with many new cables laid alongside existing ones it will look horrid and introduce many failure points with inline splices etc.

 

[robertotoole]

Most of the rest of my wiring has already been changed, so possibly not so bad. I have Oxford heated grips. My indicators are all non-BMW. Dash has already been replaced with an Acewell. So maybe I could just fit a new rear loom. It looks like the older loom doesn't have a front sub-loom like the later version, so that simplifies things. Simpler will be better.
No load-shedding relay - is that a problem?

 

[Gelandestrasse]

Maybe it will be cheaper if you make up your own loom, with all the modifications you have. You'll only end up buying a new one and cutting it up. As for load-shedding relays, I listed it as just another thing that is not there on the early model. My list was not exhaustive. It is up to you what relays and other electrical components you have on your bike - if you can't judge what is a problem then......

 

[robertotoole]

...then?

 

[Gelandestrasse]

Well, I'm not really sure what question you were asking when you asked about the load-shedding relay. You could be an electrical guru and were just asking rhetorically with a sort of 'shrug shoulder' emoji yeah, everyone knows about those relays...

But because you were asking basic questions, which I used my Haynes manual (I recommend you get one) for my response (and I own a post-1991 GSPD, so have some little experience), I guessed you might not have a clue, but that was a guess. But you mentioned all the other electrical mods to your bike which you seemed knowledgable about, so I again guessed you might not be clueless. With all this doubt in my mind I left my response hanging, so you could fill in your own response. It's your bike; you put on it what you want, you take off what you want.

You can get an awful lot of help on this forum and I've seen an awful lot of hate from time to time. I'm trying to be helpful.

 

[robertotoole]

Thanks.

 

[robertotoole]

I just researched the load shedding relay. I think it must have been added to cope with US bikes having to have headlights on all the time. As I don't start the bike with the headlight or any accessories on (and the light is an LED now anyway), it's not needed.

 

[robertotoole]

Another strange twist to my GSPD loom investigation: i've just got a new ignition key barrel and wiring from Motorworks. It's the correct one for my 1993 bike. But it turned out that my bike had a 3 position barrel, and it seems that the correct one is 5 position. So with the new one in place I get weird results, and no way of switching the bike off and taking out the key. In what was the off position, I now get the parking light and the rear light switched on, even with the key out! But I can't get the ignition on and the rear light operating at the same time. I can get the ignition on, and take the key out without switching the ignition off.

Coincidentally, I'm about to buy a new Honda!

 

[robertotoole]

But, checking the owners handbook I can see that the switch is supposed to have just three positions. So is it that Motorworks and others are selling the wrong ignition barrel? I think it's not the original BMW part, so maybe that is why.

 

[Mad Hatter]

The Motorworks ignition switches are pattern parts not BMW but they work OK. The wiring diagram will show a 3 position switch and a 5 position switch with the different internal connections

 

[robertotoole]

Motorworks are being helpful. I've created a video to show them what it does. The switch might actually be faulty. Or perhaps I'm faulty!

 

[robertotoole]

I tested the ignition barrel wiring and found that it is malfunctioning, with a short circuit when the key is in the off position. So it's on its way back to Motorworks.
I've also had a go at fixing the wiring on my original, and got it working. Not ideal, but at least I've learned a bit about how it works.

 

[Jem Wilton]

I tested the ignition barrel wiring and found that it is malfunctioning, with a short circuit when the key is in the off position. So it's on its way back to Motorworks.
I've also had a go at fixing the wiring on my original, and got it working. Not ideal, but at least I've learned a bit about how it works.

Well done mate - well sorted... I've got an old bumblebee and electrical malfunctions a plenty. I've found it's just best to track and trace using a meter and substitute bits when and where you can. The main loom connectors above the coils were green with corrosion giving me all sorts of gremlins whch could be diagnosed a load of different ways. Cleaned 'em all up with a dremel and there are fewer now...

 

[robertotoole]

About 10 years ago I stripped the main loom, cleaned all the connectors, and re-wrapped it. I didn't find corrosion, just a lot of dirt. It does all seem to be good quality. Connectors and wires aren't going brittle. The broken ignition key wire (on the original, not the Motorworks one) was my fault. I moved the position of the barrel into a nice new aluminium bracket, and didn't check the routing of the wire correctly. The first time I put the bars to full lock one of the wires pulled out. The bike suddenly went very dead.