Any advice, thinking of running a new earth to test if it is earth from headlight , all wires look fine , no corrosion
Wow , what an extensive and detailed question, well done . Have you tried a new main beam bulb? It may simply be the bulb that’s at fault, working ie illuminating but too much resistance. iirc, isn’t it a shared earth path for all off side, dipped and main beam bulbs? If so, and if it were the earth path at fault then I’d expect to see similar results on the dipped beam (unless the issue were in the short piece of cable from main bulb connector to where it joins the rest of the earths). Have you measured the resistance over the earth path from main bulb connector to battery -ve? It should be virtually negligible. You could also disconnect the main beam connector, short the +ve & -ve terminals, switch on main beam, and measure the voltage. It should, of course, not drop as there’s no load in the circuit. It will help you identify whether the bulb is the culprit or the earth path. One other thing to consider is the fact there’s one other load on the circuit when it’s on and that’s the small main beam warning light inside the clocks. Finally, it could also be a symptom of a failing r/r whereby it can’t maintain the required voltage output as the demands on the system increase.
Wow , what an extensive and detailed question, well done . Have you tried a new main beam bulb? It may simply be the bulb that’s at fault, working ie illuminating but too much resistance. iirc, isn’t it a shared earth path for all off side, dipped and main beam bulbs? If so, and if it were the earth path at fault then I’d expect to see similar results on the dipped beam (unless the issue were in the short piece of cable from main bulb connector to where it joins the rest of the earths). Have you measured the resistance over the earth path from main bulb connector to battery -ve? It should be virtually negligible. You could also disconnect the main beam connector, short the +ve & -ve terminals, switch on main beam, and measure the voltage. It should, of course, not drop as there’s no load in the circuit. It will help you identify whether the bulb is the culprit or the earth path. One other thing to consider is the fact there’s one other load on the circuit when it’s on and that’s the small main beam warning light inside the clocks. Finally, it could also be a symptom of a failing r/r whereby it can’t maintain the required voltage output as the demands on the system increase.
See if this improves things - run a jumper cable from the battery negative to a good earth on the engine or frame.
Thanks Paul Full disclosure , I am not an expert with the multimeter, please excuse any errors, Hayes manual and YouTube are my guides, if anything looks off ths scale, just shout For me Dipped beam is first position on light switch Main beam, second position Full beam is light switch at second position and red full beam button pushed Changed the h3 main beam bulb, no difference resistance over the earth path from main bulb connector to battery -ve, this was 3.92 ohms , I removed , all headlight grounds/contacts, i cleaned with contact cleaner and dielectric grease , no change from 3.92ohms All plugs on the bike are regularly checked, cleaned with contact cleaner, dielectric grease as required I am thinking of creating a new earth to test But when I turn on the full beam , it pulls it down to 11.2 from 12.1v (main beam on) , no idea if one faulty earth on the main beam would also affect the full beam disconnect the main beam connector, short the +ve & -ve terminals, switch on main beam, -- will try this later , bulb disconnected and switch on, it stayed at 13.8v small main beam warning light inside the clocks, is led , i run an led dash ,translogic R/r also has a new wiring harness from a triumph , PnP on the rec , fitted with the new rec back in 2022
Will do I also have the exact start upgraded battery cables fitted a few years The bike, runs fantastic until I turn on the main beam
As you achieved the stator and regulated requirements i would be looking at looms and connectors between regulator and stator and earths (as said). You can't rule out some kind of live earthing/short circuit in the lighting system either. Often told people to grab either of the connector plugs coming from the regulator after the bike has been running for a few minutes, as with the std connectors fitted, they are often warm.
May not apply! Or its possible! But just in case, perhaps you have an earlier or SP alternator fitted? My SPS has always been marginal and will not idle very well with the lights on. Its been like it from new, it always runs perfectly otherwise. All due to its low output alternator. Never worried me! As I say. Just a thought
Thanks for the replies , I have her a few years , I rarely drive in the dark but I have ran the main beam at times , what struck me this time was the drop in engine power when turned on , never did that before More tests disconnect the main beam connector, short the +ve & -ve terminals, switch on main beam , 13.8v Main beam on, full beam light bulb disconnected, 12.5v Main beam on , new cable for earth 12.5v Full beam on , Main beam plug disconnected , 12.5v Cables on the harness 51010821A Maybe a new harness is worth a go , at 100 gbp 51010821A
?? I dont comprehend your reply, alternator and rectifier was tested as per workshop manual , everything passed ,It's in the first post i am progressing onto the next posssible cause with the help of members here
This is what i would start with If you have some 2.5mm or 4mm wire connect between battery -ve and main beam earth then switch on light, measure voltage if it’s better/ok it’s a bad earth
Yes, 12.15v Main beam ve+ battery ve- Across the battery was the 13.48v under the same conditions, main beam on earthed to battery -ve
Then if as you say a separate earth was connected directly between the battery and the bulb earth (-ve) it looks like the issue is on the supply to bulb Do you have a wiring diagram Worth checking feed to and from fuse (if there’s one in the cct), likewise, if a a relay is involved needs checking (in and out), or is it switched directly from the switch, same applies All measurements should be taken with black meter lead connected to battery
