Daytime light relay

Schurminater said:
Hi Rob,

Yes I have one of Teds excellent wiring diagrams,........and No there is no clicking of the relay when switching......however, I may be chasing a red herring here as my current battery is only reading 10.2 volts and is planned to be replaced imminently as its now 4 years old (in fact I have just ordered the replacement.)

I expect 12 V relays need at least near that to operate???

I've checked all the head light/parking light wiring and it all seems as it should be.

I expect I might even find a brighter rear light with a brand new battery too!
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Right - that suggests the problem lies with relay wiring (notwithstanding the duff battery!) Relay ought to pull in with <12v but no guarantees with battery flat on its back! You could double check by hooking up your battery charger and trying to listen for the click again.

Next step is to check that you have 12v with new battery (or battery charger hooked up) and headlight on at terminal 86 on the relay (yellow/white). If not, dive into the headlight and check your two diodes (black plastic encapsulated things) are present and correct. White/yellow should be on terminal 51 with a yellow wire loop to 51 on the second diode.

Separately, check that the green wire (removed from relay terminal 85) measures zero ohms resistance to battery negative. Or if you can't measure resistance, and with the green wire connection made to terminal 85, try and measure the volts from it to battery negative with headlight on. Should be at or around zero.
 
Onto it Rob, great explanation and trouble shooting guide, your a star!

And in my defense I only found out the battery was low voltage whilst doing wiring checks...;)
 
Okay so we are getting somewhere but not completely fixed yet.

Originally I didn’t have 12 volts at the terminal 86 only around 6.8. - 7V
Resistance on the green wire was zero ohms and I couldn’t register any voltage either.

Dived into the headlight as requested and found the 2 diodes and confirmed White/yellow connected to terminal 51.
However what I did notice was that according to the wiring diagram there should be 2 white wires exiting the first diode and 2 yellow wires exiting the second. (Terminals 59)
these were transposed.

Swapping these around so correct to wiring diagram made a difference and I now heard clicking at the relay…..great!…..and switching from sidelight to headlight it now clicks.
However this was with the headlight/sidelight disconnected.

If I connect the headlight up it will work once ie parking light switches off with headlight on,but then the headlight dims slightly and the parking light will stay on and the relay stops clicking?
So am I now chasing an earth issue ?…..but where?…..headlamp?

To add to this with the headlight disconnected also the tail light is back to its usual brighter self.

Strangely enjoying this!!!!!
 
Success!!!.........it finally works........not sure exactly how we resolved it other than checking the earth wires and connections around the headlight but its now working as it should be.

I thought originally that I was going to have to introduce another earth lead direct from the headlight to earth, as the diagram showed one more than I had but on checking them it was clearly earthing okay.

Thank you to all that contributed to the trouble shooting and a big THANK YOU to Rob for your clearly written guidance and instructions, they were much appreciated.
 
Rob said:
So is this with you operating the LH handlebar light switch from head to sidelight? Or does the headlight dim with you doing nothing?
Click to expand...
Hi Rob, yes it was when operating the LH handlebar switch, but now all seems to be good, it will be interesting to see if it stays that way now OR I've reconnected a loose or dodgy connection somewhere and it reappears!

thanks again.

Steve
 
Great news Steve. I'd check the green earth wire on the rear mudguard (? - from memory) is clean and tight which the relay and rear light rely on
 
I hate that! Fixing an electrical fault without knowing what you did. You can never be confident that it's permanently fixed, and if it happens again you still don't know what to do about it.
 
Dellortoman said:
I hate that! Fixing an electrical fault without knowing what you did. You can never be confident that it's permanently fixed, and if it happens again you still don't know what to do about it.
Click to expand...
Totally agree,.....but I think ultimately it was an earthing issue around the headlight, the wiring around the diodes was wrong compared to the wiring diagram and changing that certainly seemed to kick start the relay into life.
Having disconnected and checked all the earth connections in the headlamp I'm confident they are all good and the headlamp is earthed to the bike.
So for now happy days, its working as it should ,I've fitted a new relay (as insurance) and a new battery is going in today, plus an uprated H4 headlight bulb so fingers crossed until the next time!
 
An interesting thread, the wiring of this relay is useful for anyone fitting daytime running lights. It seems that traffic authorities accept them, as many cars come standard with them here where headlights on is compulsory, saves the hours on the headlight globe - especially if using one of these trick expensive H4 on your bike.
 
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