Author Topic: Electrical things  (Read 226 times)

0 Members and 1 Guest are viewing this topic.

Phil C

  • Royal Star
  • ***
  • Posts: 210
    • View Profile
Electrical things
« on: 16 March, 2018, 16:54:58 »
Pilot light bulb had blown so I got a new one. Didn't work. Armed with my new multimeter and almost no knowledge, I tested between the live battery terminal and the pilot light connection: about 6v, so I guess okay. Tested continuity of bulb on my resistance (ohms) setting: about 0, so presumably okay. Tested continuity from headlamp hole (where spring clip of pilot light clips in) and battery earth point: about 0, so I guess okay. Across the battery terminals I get a reading of about 6v, so I guess okay. If I press the rear brake pedal, the brake light comes on. So why doesn't the bulb work? Am I missing something blindingly obvious?  Phil (novice)

PS If I am asking too many questions on this forum, please could someone let me know - I won't be offended!

AWJDThumper

  • Empire Star
  • *****
  • Posts: 543
    • View Profile
Re: Electrical things
« Reply #1 on: 16 March, 2018, 17:37:40 »
You need to measure the voltage between the live connector inside the pilot bulb holder and the battery earth connection (positive terminal). This should be 6V. If you actually did the test between the bulb live terminal and the live (negative) battery terminal you should get 0V.

Assuming you get 6V from the above test, take off the pilot light holder and unplug its cable and check it lights ok when connected across the battery terminals. If not, and the bulbs ok, the live contact inside the bulb holder may need to be cleaned or tweaked. If the test is ok, put the bulb holder back into the headlight shell and connect back up, and then run an earth wire from the engine or battery to the outside of the pilot bulb holder. If the light comes on then you have a bad earth connection at the holder.

Phil C

  • Royal Star
  • ***
  • Posts: 210
    • View Profile
Re: Electrical things
« Reply #2 on: 19 March, 2018, 10:07:52 »
Thanks for this AWJDT. Can I ask a very stupid question: when measuring the voltage between the battery earth connection and the pilot light bulb holder, can I do that with the bulb holder disconnected from the headlamp and the bulb taken out, putting my probe on the contact that the bulb would go against? Or does the circuit have to be in place for me to test it?

By the way, when the bulb holder and its wire are put across the battery, the bulb lights up, so it's not the holder or the bulb. Which is what I expected, as the headlight isn't working either, and I guess the pilot light and the headlight have the same problem.

Phil (novice)




AWJDThumper

  • Empire Star
  • *****
  • Posts: 543
    • View Profile
Re: Electrical things
« Reply #3 on: 19 March, 2018, 10:56:33 »
The connections to the pilot bulb are through the live contact inside and at the bottom of the holder, and the outer case which should normally be earthed via the headlight shell.

The lighting switch has 3 positions: OFF, Pilot Lights, and Headlights. The 6V power from the battery to the lighting switch connects through the ammeter to Terminal 2 (T2) via a brown and white wire.

With the lighting switch in Position 2 (Pilot Lights), T2 is then connected internally to T1 which then goes to the pilot bulb via a red and black wire. In this switch position, you should be able to measure 6V on the end of this red and black wire. The other multimeter probe should be connected to ground (engine metal or battery +ve terminal will do). If you don't measure 6V on the red and black wire, check you get 6V at either end of the brown and white wire showing it's getting to the lighting switch. In addition to T1 and T2 being connected together in this switch position, T8 & T11 should also be connected to T2 providing 6V to the rear light via a brown and green wire, and to the speedo bulb via another brown and green wire. If the rear light is working, it would at least mean that 6V is at least getting to the lighting switch.

In position 3 of the lighting switch, T2 is then connected to T3 providing 6V to the headlights via a blue wire. Assuming the lighting switch is working and the bulbs are ok, the only thing that would explain both the pilot light and headlight not working is 6V not getting to T2.


Phil C

  • Royal Star
  • ***
  • Posts: 210
    • View Profile
Re: Electrical things
« Reply #4 on: 19 March, 2018, 11:05:40 »
Okay so the answer to my first question is yes? Ie to check voltage at the pilot live connector I can have one probe on the battery +ve terminal, and the other on the pilot live connection but with the bulb and its holder disconnected from the headlamp, ie holding it in my hand?  Phil (novice)

AWJDThumper

  • Empire Star
  • *****
  • Posts: 543
    • View Profile
Re: Electrical things
« Reply #5 on: 19 March, 2018, 11:08:04 »
Yes.

AWJDThumper

  • Empire Star
  • *****
  • Posts: 543
    • View Profile
Re: Electrical things
« Reply #6 on: 19 March, 2018, 11:08:51 »
What lights actually work on the bike? I know the pilot light and headlight don't work but what about the tail light and speedo light (if you have one)?

TIGER

  • Blue Star
  • **
  • Posts: 57
    • View Profile
Re: Electrical things
« Reply #7 on: 19 March, 2018, 11:28:36 »
Phil
      Forgive me if this is repetition.
      Are you following a wiring diagram.
Also
      If you are anywhere near Staffordshire I could offer some hands-on help.
Regards
            Tim



AWJDThumper

  • Empire Star
  • *****
  • Posts: 543
    • View Profile
Re: Electrical things
« Reply #8 on: 19 March, 2018, 11:32:38 »
Here's one if you haven't got it handy.


Phil C

  • Royal Star
  • ***
  • Posts: 210
    • View Profile
Re: Electrical things
« Reply #9 on: 19 March, 2018, 12:56:25 »
Thanks both of you. There's a bit of progress! I had no lights at all, including no tail light or speedo light. So -  thanks for your help - it seemed the problem lay either between the -ve battery terminal and the ammeter, or between the ammeter and T2. My meter showed 6v at the in connection to the ammeter (NU). So the problem would be between there and T2. At the other (out) ammeter connection, where three wires come off the ammeter, there was 0v. But I waggled the connection a little bit, and got 6v and lights! Hurray!  The connection, at a glance, looks okay (see photo), but I guess I need to take the three wires off, and make sure there is a good clean connection. The ammeter now shows -4v when the lights are turned on, so I hope is okay. I guess the problem was either the connection, or an intermittent break in the wire between the ammeter and the light switch (NW)? So anyway I'm chuffed at the moment!  But I still don't get why, at the start of all this, as well as my lights not working, the engine was cutting out immediately the headlight was turned on. Any thoughts please?  Thanks very much.  Phil (novice)

AWJDThumper

  • Empire Star
  • *****
  • Posts: 543
    • View Profile
Re: Electrical things
« Reply #10 on: 19 March, 2018, 13:57:03 »
As said before - your headlight wiring looks very neat which is always good. It's best to take of the connections and clean everything up with fine emery paper if necessary.

In terms of your original problem, the battery's 6V goes to the lighting switch via T2 but goes to the ignition switch from the ammeter via another brown and white wire to ignition switch T12A. So if the main problem was the 3-wire ammeter connection, that would have robbed battery power input tom both switches - hence, no lights and no ignition :)

Phil C

  • Royal Star
  • ***
  • Posts: 210
    • View Profile
Re: Electrical things
« Reply #11 on: 19 March, 2018, 15:23:44 »
Thanks and, based on your advice so far, I expect you are dead right. I do wonder a bit why the bike would even start, but I guess if it were a poor connection then it might just start at a good moment. Come to think of it the bike took quite a few kicks before it started.  Thanks again.   Phil (novice)

PS I've ordered the bits for my petrol tank fixing.