Intermittent Electrical failure

Post your post 1970 technical queries here

Moderator: Moderators

Lionel Smith
Forum User
Posts: 14
Joined: Sat Jul 02, 2016 11:32 pm
Country of Residence: UK

Intermittent Electrical failure

Postby Lionel Smith » Thu Jul 12, 2018 10:36 am

I have an electrical issue on a 1990 R80 where the Voltmeter, indicators and horn go to sleep for a while before returning. The bike runs and I am sure with some of the distances covered, charges OK. I have checked for loose connections and sprayed the LH switchgear inside with non conducting spray.
I have checked it is not left or right turns or front suspension travel that starts it. It first started when I hit the horn (someone in the left lane of a dual carriage turning right at a roundabout!) however, does not re-occur on this action. When left overnight with these items not working the generator light did not show on starting.
Before I fork out for new LH switchgear. and strip each wire out to examine them, has anyone had this before and found the solution? I need an MOT and it could occur or maybe not.

kettle738
Forum User
Posts: 39
Joined: Thu Jul 06, 2017 5:12 pm
Country of Residence: United Kingdom

Re: Intermittent Electrical failure

Postby kettle738 » Thu Jul 12, 2018 11:18 am

Does it start normally....does the starter motor spin at good speed every time? I had a fault where the starter motor failed to work, I would press the button, there would be a loud metallic 'clack' and all the electrics would die....all out, completely dead, and yet the battery was excellent and no fuses were affected.....all terminals were clean and tight.

Long story short....AFTER changing the starter motor for a known quantity I discovered the main negative lead to the battery had rotted away about an inch inside the sleeving, it was completely invisible and I only found out when the upper connector came away in my hand....possibly not your situation, but in my case everything bar the starter worked normally, and the fault appeared very quickly.....one day it would start (sluggishly) next day it killed all the electrics as described.

Mick.

User avatar
windmill john
Forum User
Posts: 3298
Joined: Fri Feb 18, 2011 9:58 am
Country of Residence: England
Location: Somewhere in Southern England. bip bip bip, loose lips sinks ships

Re: Intermittent Electrical failure

Postby windmill john » Thu Jul 12, 2018 11:19 am

I’d say it is an intermittent earth issue possibly. All earthing points need checking, cleaning etc.

Regarding the L/H switchgear, take a look at this thread:

https://bmbikes.org.uk/viewtopic.php?f= ... ey#p180021

John
http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Schorsch - 1978-80 R65 - bit of a Shetland pony; frisky and naughty.
Max - 2009 F800GS- where’s the desert at!?
Too many bikes have come and gone, trying to be sensible now!

User avatar
windmill john
Forum User
Posts: 3298
Joined: Fri Feb 18, 2011 9:58 am
Country of Residence: England
Location: Somewhere in Southern England. bip bip bip, loose lips sinks ships

Re: Intermittent Electrical failure

Postby windmill john » Thu Jul 12, 2018 11:20 am

Honestly Mick, if you’d told me me you were typing at the same time, I could have saved my finger! :wink:
http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Schorsch - 1978-80 R65 - bit of a Shetland pony; frisky and naughty.
Max - 2009 F800GS- where’s the desert at!?
Too many bikes have come and gone, trying to be sensible now!

User avatar
boxerman
Site Admin/Club Member
Posts: 7488
Joined: Sat Jul 23, 2005 8:27 pm
Country of Residence: UK
Location: Leicester
Contact:

Re: Intermittent Electrical failure

Postby boxerman » Thu Jul 12, 2018 11:31 am

I'd suggest chaging the fuses would be first port of call. indicators and horn run through the same fuse and if it's corroded.arcing it's going to give issues.
Phil Hawksley 'The Boxer Man' - aka 'Dangermouse'
Member #1 Much modified R80G/S - a REAL one
Why not join the BM Riders Club @ http://www.bmridersclub.com
http://www.boxerman.co.uk
http://www.bmbikes.co.uk
https://twitter.com/boxermanphil for my Badger videos

User avatar
Galactic Greyhound
Moderator
Posts: 8785
Joined: Sat Aug 28, 2010 11:26 pm
Country of Residence: Scotland
Location: Dumfries

Re: Intermittent Electrical failure

Postby Galactic Greyhound » Thu Jul 12, 2018 12:29 pm

I'd suggest chaging the fuses would be first port of call. indicators and horn run through the same fuse and if it's corroded.arcing it's going to give issues.

+1 :smile:

The Voltmeter, Indicator Relay and the Horn are all supplied from the same fuse as Phil says.

The Voltmeter also failing is the clue that the problem is NOT in the Lighting/Horn/Indicator Switchgear as the Voltmeter, unlike the Horn and Indicators, does NOT go through these switches.

The Voltmeter, Indicator Relay and Horn fuse, receives +12v on a Green wire from the Ignition Switch to the fuse.
It is NOT a fault in the Ignition Switch as this also supplies your Ignition, Starting and Lighting which are working OK.

You are therefore looking for a problem on the twin Fuse Block on the lower fuse (as shown in the Haynes Diagram) terminals marked '15' (Green, +12v supply In from Ign Switch) and the '15S' (Green/Black, +12v out to Voltmeter, Indicator Relay and the Horn).

Check that the clips holding the fuse are exerting sufficient pressure on the fuse and are not fatigued or corroded so causing an intermittent connection.

You can use a test meter or a bulb to check that there is +12v coming into the fuse on the Green wire and +12v going out of the fuse on the Green/Black wire.
With the test meter/bulb on the Green/Black +12v out wire, move the Green and Green/Black wires and the fuse to see if you can bring on the fault.
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

User avatar
Rob Frankhamr
Club Member 13
Posts: 2442
Joined: Mon Jul 25, 2005 6:33 pm
Country of Residence: Scotland
Location: Kinloch Rannoch, Perthshire

Re: Intermittent Electrical failure

Postby Rob Frankhamr » Thu Jul 12, 2018 5:06 pm

I'd suggest chaging the fuses would be first port of call. indicators and horn run through the same fuse and if it's corroded.arcing it's going to give issues.

+1 :smile:

The Voltmeter, Indicator Relay and the Horn are all supplied from the same fuse as Phil says.

The Voltmeter also failing is the clue that the problem is NOT in the Lighting/Horn/Indicator Switchgear as the Voltmeter, unlike the Horn and Indicators, does NOT go through these switches.

The Voltmeter, Indicator Relay and Horn fuse, receives +12v on a Green wire from the Ignition Switch to the fuse.
It is NOT a fault in the Ignition Switch as this also supplies your Ignition, Starting and Lighting which are working OK.

You are therefore looking for a problem on the twin Fuse Block on the lower fuse (as shown in the Haynes Diagram) terminals marked '15' (Green, +12v supply In from Ign Switch) and the '15S' (Green/Black, +12v out to Voltmeter, Indicator Relay and the Horn).

Check that the clips holding the fuse are exerting sufficient pressure on the fuse and are not fatigued or corroded so causing an intermittent connection.

You can use a test meter or a bulb to check that there is +12v coming into the fuse on the Green wire and +12v going out of the fuse on the Green/Black wire.
With the test meter/bulb on the Green/Black +12v out wire, move the Green and Green/Black wires and the fuse to see if you can bring on the fault.

Well reasoned...

Assuming it is the fuse (and assuming the wiring diagrams in Haynes can be trusted at this point) you will also lose the brake light (both switches) and the headlight flash function. Both of these are fed from the same source.

If it turns out that the fuse looks good, use a multimeter to test for battery voltage at the live side of the fuse. That is the side with the single green wire connected to it.

If that checks out OK, check the other side of the fuse (2 x green/black wires).

If the first test doesn't check out OK, suspect the green wire. The other end goes to the 'Kill' switch in the right hand switchgear.

If the first test is OK but the second isn't, there is a fault with the fuse or the fuse holder.

Finally, if both tests check out you need to check the connection on the down side of the fuseholder (2 x Green/Black wires).

Unless I'm grossly mistaken, the fault isn't going to be further down the circuit than the downstream side of the fusebox because there are two seperate circuits from there and both are affected. It also isn't going to be further up the live side of the circuit than the kill switch because that controls several circuits that aren't affected.

Hope that makes sense and helps.

Rob
Last edited by Rob Frankhamr on Thu Jul 12, 2018 10:19 pm, edited 1 time in total.
Robin Frankham
ImageImageImage

Frankhams retirement home for elderly Boxers.

User avatar
george baker
Moderator/Club Member
Posts: 7001
Joined: Mon Aug 01, 2005 10:51 am
Country of Residence: uk
Location: Manchester,UK

Re: Intermittent Electrical failure

Postby george baker » Thu Jul 12, 2018 8:38 pm

Hi
I had a problem like that, fuse checked out ok as did feed to and voltage from it using a multimeter.

The problem turned out to be plastic fuse that had burn down a couple of mm. The Fuse carrier held the fuse in place but when a load was applied (horn) I got a high resistance joint.

I should have checked the feed to and power=voltage x current out it using a test lamp. I replaced the plastic fuse with a ceramic one

George
Member 21, R100R, K75 and a Hyosung 250 FOR SALE

Roy Gavin
Forum User
Posts: 239
Joined: Sun Jan 21, 2018 9:29 am
Country of Residence: Australia

Re: Intermittent Electrical failure

Postby Roy Gavin » Fri Jul 13, 2018 5:22 am

Just an observation that a large flat auto fuse fits nicely into the female flat connectors which attach to the fuse board. That is , one fuse joins the two connectors.
Much easier to find in a service station and if they blow it is visible.
There are also probably a few spares in one of the fuse/relay boxes on your car, if you are stuck or just need to check the existing bike fuse.
I never really felt comfortable with the BMW style of fuse, and when one did blow I replaced the fuse board with a couple of flat fuse holders, relocated to under the seat for better access.

Lionel Smith
Forum User
Posts: 14
Joined: Sat Jul 02, 2016 11:32 pm
Country of Residence: UK

Re: Intermittent Electrical failure

Postby Lionel Smith » Fri Jul 13, 2018 5:14 pm

Thanks Phil, Ced and Rob,
Absolutely bang on! I removed the Fuse box cleaned all the contacts and fuses, bent the contacts back in and hey presto, fault fixed.
Daisy should make it through the MOT now.
Lionel :grin:

User avatar
Galactic Greyhound
Moderator
Posts: 8785
Joined: Sat Aug 28, 2010 11:26 pm
Country of Residence: Scotland
Location: Dumfries

Re: Intermittent Electrical failure

Postby Galactic Greyhound » Fri Jul 13, 2018 7:18 pm

Thanks for the update - happy riding! :smile:
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

User avatar
andyb
Forum User
Posts: 503
Joined: Fri Jul 12, 2013 9:40 am
Country of Residence: uk
Location: Notts, UK

Re: Intermittent Electrical failure

Postby andyb » Fri Jul 13, 2018 8:15 pm

I had a problem with the same circuit blowing the fuse - turned out to be the heated grips shorting out as they are also on that circuit.
Andyb
R100R work-day-bike
Moto Guzzi V7 Stone fun-day-bike

User avatar
Rob Frankhamr
Club Member 13
Posts: 2442
Joined: Mon Jul 25, 2005 6:33 pm
Country of Residence: Scotland
Location: Kinloch Rannoch, Perthshire

Re: Intermittent Electrical failure

Postby Rob Frankhamr » Fri Jul 13, 2018 10:25 pm

Thanks Phil, Ced and Rob,
Absolutely bang on! I removed the Fuse box cleaned all the contacts and fuses, bent the contacts back in and hey presto, fault fixed.
Daisy should make it through the MOT now.
Lionel :grin:
:thumbup:
Robin Frankham
ImageImageImage

Frankhams retirement home for elderly Boxers.


Return to “Airhead Q&A's”

Who is online

Users browsing this forum: No registered users and 8 guests