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Yes clymer
1992 R80GS PD = switched live, without ignition interruption?
- Thread starter sidkn33
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The clock for a PD (or any post-91 GS) is a digital thing (look up where it is mounted) and has its own feed from the loom (4 wires, red/white included). There's a feed for heated grips and one for a hazard switch too. The additional instruments connector (according to my Haynes Manual diagram) has 2 wires, red/white and brown so no good for a voltmeter. Perhaps for another auxiliary socket? Can't think of an auxiliary instrument that needs a permanent live. Maybe someone here can....
So, 'not as designed' for me is an interpretation of your original fault - the feed for your speedo going to zero when you start the bike. By design, that 'permanent power supply' should not go to zero when you start the bike. By 33-year old wiring and perhaps more than one owner's modifications and possibly other underlying faults, who knows what design standard your bike is actually at? This isn't a criticism, just a view on the lack of facts available for us to evaluate and help you with, hence my 'what if' approach. What colour wire did you pick for your 'permanent power supply'?
My next 'what-if' is this: you mention "because pressing the starter button interrupts power to every switched live source I have located using my voltmeter and therefore reboots the speedo every time I start the bike) is there a switched live that does not get interrupted by the start button/starter motor?" The switched live circuit is green/black. There is also grey/black for the parking lights. That is switched, too. The green/black circuit goes through the load-shedding relay (it also goes to the indicator cancel button but that is irrelevant here (hopefully)). So if your speedo is connected to the switched live circuit then that is your issue. The answer to your question is no - unless you use the lighting circuit for your speedo. The grey/black lighting circuit does not go through the load-shedding relay.
So maybe bringing the auxiliary instrument feed to bear here is your best bet? Like, connect it to the permanent live feed your speedo requires?
Thanks for the detailed response. It's appreciated.
My PD has factory heated grips and hazard lights, just as an FYI.
I'm away for a few days but will take a close look at (and voltmeter probe) my wiring using all this valuable info.
I'm wondering now if there's something bespoke about the additional instruments wires in my loom - that's what I believe the speedo is connected to, but will review ASAP
My battery shows a momentary drop to circa 9v when starting
After further checks, the speedo is currently connected via wires from the main loom thus:
Red/white = permanent live to speedo digital clock power
Grey/blue = switched live interrupted by starter, to speedo backlight and main power
Brown = ground to speedo ground
I have now tried every wire from the main 4x fuses box and the behaviour is the same - starter interrupts the live supply on all.
Across the four fuses I have
Black Green to Yellow Green
Grey Black to Grey
White Red to Red
Brown Green to Blue Green
Red/white = permanent live to speedo digital clock power
Grey/blue = switched live interrupted by starter, to speedo backlight and main power
Brown = ground to speedo ground
I have now tried every wire from the main 4x fuses box and the behaviour is the same - starter interrupts the live supply on all.
Across the four fuses I have
Black Green to Yellow Green
Grey Black to Grey
White Red to Red
Brown Green to Blue Green
try swapping the losd shedding relay
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I would agree
Thanks,
Just looked on Motorworks, they list a "load shedding relay" for K bikes
with filter for my R80GS PD (correct, later series), no Load Shedding Relays are available.
A starter relay isn't a load shedding relay (is it?) and if it is, how is there a starter and a load shedding relay on a K bike, and only a starter relay on my R80GS
I thought I was confused enough and then, this.
difficult to photo the numbers on mine, but has 402 on the side
Green wire to coil is switched live!
I was trying to remember Green Black is also a switched live
Headlamp circuits are Load shedded
but if I recall not Sidelamp Circuits and brake lamp circuits they should always be Switched live, non interrupted
Sounds like some one has been playing with your bikes wiring ? Did I see a pic somewhere of your loom near a Dyno coil with insulating tape wrapping it ?
based on the pin layout, maybe this one?
People really do end up running in circles with this stuff
Diagnose! Don't Guess!
As a test If you have the headlamp on and press the starter button then your headlamp goes out whilst the starter button is pushed? Correct??
Don't turn off the ignition!
Just pull the relay
Does the headlamp go out immediately
Congrats you have just found your Load shedding relay
And if the headlamp goes out when the starter is pressed it is working
Its just a breaker to the higher current components of the electrical circuit
@sidkn33 DOOOODE !!!!!!
Go do the test and stop obsessing with this!!
If you have the headlamp on and the Starter button interrupts the circuit Then the relay is working!!!!!!
Reach in and pull the Relay "Without" switching off the ignition and the headlamp goes out you have verified that this is the load shedding relay
It is Normal to see some voltage drop in a circuit when the starter is pulling Amps!!
Don;t use a DVM use an incandescent bulb ! DVM can fall out of calibration
So link in an indicator bulb for example on the circuit you want to test the voltage drop in
Just how badly does it dim ??
Yes, re sidelamp and brake circuits, but on mine they are all interrupted, it seems.
Possibly someone has been playing (other than me and I know that all I've done is run a wire from switched live in the fuse box, to feed my LED fog lights, Acewell speedo and USB port)
You've lost me on
"a pic somewhere of your loom near a Dyno coil with insulating tape wrapping it"
Do you mean this?
If so, it's the relay for my LED fog lights - with extra tape!
I
I will pull the LS relay to confirm and test the load behaviour using a bulb as you suggest. Thanks.
Not obsessing, I'm following several people's helpful suggestions in this thread, that the problem with all my switched live wires being interrupted by the starter (this not being expected behaviour) is (possibly) caused by a bad load shedding relay.
I will pull the LS relay to confirm and test the load behaviour using a bulb as you suggest. Thanks.
I fear they may be Unintentionally leading you on a bit of a wild goose chase
To Explain, Your bike has 3 "main" circuits
Permanent Live (Solid red)
Switched Live Green (and Green Black, I think)
And "Interrupted Live" All those that run through the LS relay
AS @mikeyboy has mentioned it sounds like someone has been messing
Switched and interrupted should never be linked
SO as a failsafe and definitely not going to be interrupted, you can test the Green to the coil as it is 12v +ve on switch on
OR If the test identifies the LS relay as the one you suspect when you pull it out ?
Leave it out and see what stays live ??
To Explain, Your bike has 3 "main" circuits
Permanent Live (Solid red)
Switched Live Green (and Green Black, I think)
And "Interrupted Live" All those that run through the LS relay
AS @mikeyboy has mentioned it sounds like someone has been messing
Switched and interrupted should never be linked
SO as a failsafe and definitely not going to be interrupted, you can test the Green to the coil as it is 12v +ve on switch on
OR If the test identifies the LS relay as the one you suspect when you pull it out ?
Leave it out and see what stays live ??
You are not the first! How do you think I learned all this stuff
Hmmm Is the loom on your Bike still in its original sheath and is the sheath still pliable
I just had a thought where the two circuits could be crossing !!
Thanks a bunch for the input - especially re the different circuits.
The relay I show above does cause the headlight to go out when pulled so that's the LS relay.
I will now, leave it out and hunt for a switched live.
My loom looks original, unmolested and in good condition (for 30+ year old wiring anyway).
