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I seem to have lost the idiot lights on the instruments. I know where they are of course, but they're just not working.

I have removed the instruments, to test another set, and when reinstalled the original lot doesn't have anything. that of course creates a problem. No GEN light, no charge.

Now, the neutral light has been intermittent, on turning left, and occasionally the other lights too. Even the tacho needle drops back.

So I'm thinking here that there is a break in the wires. I can get the test light to work on terminals 8 & 10 on the big connector that fits into the rear of the instruments, but only if I wriggle the wiring around edit: right up close to the connector. That connector appears to have the wires molded into the back of it.

Do I need to replace the loom? I do happen to have 2 used spare looms.

Where's GSPD when you need him.

With multiple lights not working I'd suspect an earth wire.
But, getting power wires to test ok intermittently at the plug might suggest otherwise.
What are terminals 8 & 10 ?
Have you got a wiring diagram identifying all the wires in the loom?

8 has a green/blue wire that's from to the starter relay.
10 has a black wire from terminal 1 on the coil, and then to the icu.
The earth appears to come off 12.

These instruments have been in and out multiple times, and the disconnection of the combined connector terminal that fits into the back isn't always simple. I wonder if the movement over time has caused damage? A slight repositioning of the large group of wires (just before they enter the combined unit) whilst it's connected can cause the lights to come on or off.

I have an excellent wiring diagram to follow, but it's still electrickery to me.

Is the spare loom new or S/H?

sterob wrote:Is the spare loom new or S/H?

2 spare, both 2nd hand.

There was a new one on ebay here about 3-4 months back that sold for $290. I wish, I wish, I wish!!! Otherwise they're a small fortune. $679 from maxbmw!

...and I have a ride to the Snowy Mtns "looming" next weekend!

SteveD wrote:

sterob wrote:Is the spare loom new or S/H?

2 spare, both 2nd hand.

There was a new one on ebay here about 3-4 months back that sold for $290. I wish, I wish, I wish!!! Otherwise they're a small fortune. $679 from maxbmw!

...and I have a ride to the Snowy Mtns "looming" next weekend!

Have you checked the price of new from Mark Huggett or Motobins? Price varies with current exchange rates.

Huggett..$993
Motobins ..couldn't see one for the 11/1981 model RS.

Is that price for a whole bike loom Steve?
Stuff changing the whole thing man!
I'm thinking that more than one broken wire is unlikely, unless there is some obvious damage to the wire covering.
If the breakage is confined to the connector plug, maybe chop it off and join another plug that you have, it might save a lot of work.

Thanks everyone. That's where I'm heading Jeff.

I fear that it's that plug at the back of the instruments that is the problem. If I connect it to the instruments and manipulate it a little, the lights will go on and off. I haven't fiddled with it further down the loom at all.

The instruments themselves are good and clean in there. Where should I look for the earth?

The lower bend past the steering column is fairly tight, always has been, and the cover was split years ago. It's got electrical tape over it.

Later today I'll pull it all off and inspect there.



My feeling is that I will need to splice another plug onto the existing loom. I'll be off to re-read that soldering thread later

The rub is, I have an annual ride to the mountains next w/e, with a half dozen good friends. I hope I can get it sorted. It's already a busy week, and I'm now off to an all day family "do" to celebrate something with my lovely daughter. It'll have to wait 'til later tonight.

You can sometimes use a dental pick to reach into the holes in the plug and spring the comtact pieces toward the center of the hole. Hopefully reestablish contact. Also get some contact cleaner and spray in the plug to remove corrosion. Once it is clean and tightened up, fill the holes with dielectric grease. The grease keeps water and oxygen out to prevent corrosion.