'81 G/S Electric problem

Glynn · Mar 28, 2018

New upgraded charging system and a recon starter motor fitted.

It started and the built-in voltmeter said all was good

The next day all was not right!

Idiot lights on in the parking position - dim
Engine turns but no spark
No lights or indicators no matter which position the switch is in or the kill switch
No volts showing on the voltmeter... but shows 11 volts when the kill switch is in the kill position

Any pointers pleeeesssse !

TIA

Glynn

Steptoe · Mar 29, 2018

Glynn said:
New upgraded charging system and a recon starter motor fitted.

A better description or a clue of what you've actually upgraded might help any diagnosis.

600watt alternator ? upgraded diode board ? regulator ? etc etc .

JJH · Mar 29, 2018

Have you tried disconnecting things 1 by 1 to see if that helps? Try light the wire on the starter first. JJH

ianboydsnr · Mar 29, 2018

Sounds like a missing earth to me, there needs to be more information though.

Glynn · Mar 29, 2018

I don't doubt it's an earth...

Upgraded 600w system incl regulator, new recon starter motor.

I've unplugged all components and nothing changes.

There is a drain on the battery...unplug everything and it makes no difference. Still shows a current drop unless I take out the red ignition wire from the battery. Hot wire that from the battery to the ignition switch and get the same current drop.
By current drop I mean the multi meter across the battery dropping its reading .01 of a volt every few seconds. (After half an hour I would expect the battery to be below 12 volts)

When in the parking position I have 3 dim warning lights on. Oil/neutral/charge. Turn to ignition, brighter, but no lights or horn or indicators , nor the indicator + main beam warning lights.

Cleaned the earths behind the 2 relays. Also the one on the gearbox and battery lead

The diode board has the 2 earth leads to the alternator connected

Sent from my iPad using Tapatalk

Glynn · Mar 29, 2018

Starter motor turns the engine... No sparks
12 volts to fuses
12v to coils
Remove fuses makes no difference to current drop

solidstate100 · Mar 29, 2018

Ive had some weird leccy problems with my G/S now and again - one of which (which had similar but not quite the same symptoms as you) was as a result of the fuse box under the tank (with the thumbscrew cover and the 2 ceramic fuses in it) was corroded. Worth a look to rule it out.

Also , if memory serves me correct, there was a recent thread in here along the same lines - new uprated charging system and starter, weird electrical problems followed, eventually after much head scratching traced to a starter solenoid issue on the recon starter (IIRC).

EDIT my post just crossed with yours re fuses........

Beemerboff · Mar 30, 2018

On my G/S the harness brown earth wires earthed on one of the screws on the voltage control unit.
My unit has a plastic body , so all of the earth was through the threads of a slack rusty self tapper -----------.
If you suspect the fuse box you cam simply disconnect the flat terminals on the rear and push a large flat fuse into the connections on the wires.
Or if you have a spare two or three hundred quid I am sure Motogadget have something that will do the same, and you will have something to post pictures of too!

ianboydsnr · Mar 30, 2018

Glynn said:
I don't doubt it's an earth...

Upgraded 600w system incl regulator, new recon starter motor.

I've unplugged all components and nothing changes.

There is a drain on the battery...unplug everything and it makes no difference. Still shows a current drop unless I take out the red ignition wire from the battery. Hot wire that from the battery to the ignition switch and get the same current drop.
By current drop I mean the multi meter across the battery dropping its reading .01 of a volt every few seconds. (After half an hour I would expect the battery to be below 12 volts)

When in the parking position I have 3 dim warning lights on. Oil/neutral/charge. Turn to ignition, brighter, but no lights or horn or indicators , nor the indicator + main beam warning lights.

Cleaned the earths behind the 2 relays. Also the one on the gearbox and battery lead

The diode board has the 2 earth leads to the alternator connected

Sent from my iPad using Tapatalk

You need to find out where the drain is,
normally on old bikes, a drain with nothing switched on would point me in the direction of the diode pack, are you sure you connected it correctly, and functioning correctly?

Otherwise you need to disconnect each wire and test to find the drain, you could run a temporary earth cable from the battery, to earth points, to see if it improves matters.

Glynn · Mar 30, 2018

I will check the diode board again today.

But I have already put the old stuff back on. No difference in symptoms but don't think I had noticed the drain then.

Fuse box works fine

Earths behind the relays are good too

chrisshrops · Mar 30, 2018

I updated to a 600w system too, and had the charge light on and no charge my fault was indeed the starter motor it took me ages to find the fault, it was a brand new starter motor with a faulty solenoid.
Good luck matey

Glynn · Mar 31, 2018

I've spent enough time on this already!

Will arrange to have someone look at it this week.

I'll keep you up to date !

Glynn

JJH · Mar 31, 2018

If you have the old starter try putting it in and see what happens. JJH

Beemerboff · Mar 31, 2018

Dont exclude the main switch itself - some of the symptoms in the first post would seem to be unlikely if it was performing perfectly.
They are not hard to check but you have to remove them and then check that the terminals are being connected as required.
I reconnected mine so only the ignition/starter is live at the first click and everything else comes on at the second, but I have relays on everything and the switch only takes relay loads.
Replaced all the main and sub looms and relays, all the minor switches and sensors, PCB , and fitted a new fuseboard at the same time and now everything works as it should, for the first time ever.
Should have done it the first week I bought the bike!

Glynn · Apr 15, 2018

It's sorted!

Don't quite know what the problem was.

The starter motor had previously been on its way out...it would very occasionally stick on and not engage at all sometimes.
So I got another.

When testing the ignition control unit with another set of wires and a known good unit... I still had the same symptoms. What i didn't know is that it needs earthing to the frame. Earth it on the frame and everything is back to normal!

I have an upgraded unit with a bigger heatsink that was fitted years ago, it doesn't fit the frame mounts. So it's bolted at one end and cable tied the other. Why it choose that moment not to earth properly I'll never know

One bolt to earth obviously isn't enough....especially as the frame paint there is good.
So I have now added an earth lead to the unit.

Thankyou to all for your help, very much appreciated

'81 G/S Electric problem

Glynn

Active member

Steptoe

What a waste.

JJH

Well-known member

ianboydsnr

Well-known member

Glynn

Active member

Glynn

Active member

solidstate100

Well-known member

Beemerboff

Registered user

ianboydsnr

Well-known member

Glynn

Active member

chrisshrops

Registered user

Glynn

Active member

JJH

Well-known member

Beemerboff

Registered user

Glynn

Active member

Similar threads