« previous next »
Pages: [1]   Go Down

Author Topic: ignition switch/wire problem  (Read 2973 times)

0 Members and 1 Guest are viewing this topic.

Beakin

  • Guest
ignition switch/wire problem
« on: September 10, 2009, 08:22:32 AM »
Hi

I have a cb750F2 1977

I was going to start it up with the kickstart, it fired up and then suddenly died then the oil and neutral light were no longer lit....

When i turn my key from off to on nothing seems to happen, the battery is charged, the fuses are fine, ground wire connected, and i cant find any unpluged connections...

any suggestions?

thanks
Logged

Offline Gordon

  • Global Moderator
  • Really Old Timer ...
  • *****
  • Posts: 12,114
  • 750K1, 550K2
Re: ignition switch/wire problem
« Reply #1 on: September 10, 2009, 09:03:01 AM »
Check the plug on the back of the ignition switch.
Logged

Beakin

  • Guest
Re: ignition switch/wire problem
« Reply #2 on: September 10, 2009, 09:51:27 AM »
it was connected fine.. i tried adding pressure to it as well but no luck.. none of the lights go on and none of the controls work.. What is a good way to test if the key switch is working?
Logged

Offline Slayer

  • Hot Shot
  • ***
  • Posts: 454
  • What can I say that hasn't been said before
Re: ignition switch/wire problem
« Reply #3 on: September 10, 2009, 10:01:33 AM »
That is funny I just posted this pic to help someone trying to hot wire their bike. I had a similar ignition problem as you so I traced the ignition lines to find the short. The ignition switch to the left is what you want to test to see if the "key switch" is working. When you turn the plastic disc on the other side it should make contact like you are turning the key. How do your fuses look?

Logged

Beakin

  • Guest
Re: ignition switch/wire problem
« Reply #4 on: September 10, 2009, 11:35:53 AM »
ill have to try that, the fuses looked fine, and you could run current though them..

totally sucks since i just insured the bike yesterday for 3 months costing me 460 bones  >:(
Logged

Offline Spanner 1

  • Old Timer
  • ******
  • Posts: 4,092
  • CB 750 K0 ( always thought it was a K1!) + CB750K8
Re: ignition switch/wire problem
« Reply #5 on: September 10, 2009, 12:27:08 PM »
Slayer, where's your 4th. hand ?
Logged
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline Slayer

  • Hot Shot
  • ***
  • Posts: 454
  • What can I say that hasn't been said before
Re: ignition switch/wire problem
« Reply #6 on: September 10, 2009, 12:28:45 PM »
That just means you have to fix it now instead of later. Good luck man, do you have a wiring drawing for this bike yet?

I only have three hands, you might want to TT for more  :D
Logged

Offline old76cr

  • Enthusiast
  • **
  • Posts: 179
Re: ignition switch/wire problem
« Reply #7 on: September 10, 2009, 01:00:24 PM »
Pull the rubber cover off the back of the ignition switch. Mine died like yours and it was corroded wires at the back of the switch that had let go.
Logged
cb750 k5                                                                     76 Husqvarna 250cr                                                       77 Can-Am 175   1973 honda SL125

Offline Ogri

  • Thinks he's a
  • Hot Shot
  • ***
  • Posts: 331
Re: ignition switch/wire problem
« Reply #8 on: September 10, 2009, 01:48:48 PM »
I spent most of yesterday poring over a wiring diagram, I might be able to help.

Power goes into the ignition switch via the red wire, it exits via black, brown & brown and white wires.

I'd make (or buy) a test light using a 12V bulb. One wire soldered to the metal casing (ground) and one to the 'pip' at the bottom(live).  Use a crocodile clip to attach the ground wire to a cylinder fin. The free end of the live wire should be bared and pointy.

With the ignition on, and the key switch block connector..connected,  push the pointy end of the test lamp's live wire into the place where the red wire goes into the ignition switch's block connector on the loom side. Make sure that the test lead is actually touching the brass bit attached to the wire inside the connector. If the bulb lights then you have power going into the switch, (if it doesn't, see below.)
Now push the pointy end of the test lead into where the black wire exits on the same loom side of the block connector. If, with the ignition on, the test bulb lights then the switch is okay. If the test bulb doesn't light then the power isn't making it out the switch - the switch is faulty.

If there's no power going into the connector via the red wire then you'll need to go back to the battery and follow the + wire. First to the solenoid take-off, then to the fuse, then to the other side of the fuse etc. Sooner or later you'll get to the point where the bulb lights on one side of something but not the other.  

It might be worth checking under the tank for crushed wires, giving the ignition key in the switch a good wiggle, taking off the headlamp glass and looking in the bowl etc. Test the fuses, just because you can see the central wire doesn't mean they're okay.

« Last Edit: September 10, 2009, 02:08:25 PM by Ogri »
Logged

Offline Spanner 1

  • Old Timer
  • ******
  • Posts: 4,092
  • CB 750 K0 ( always thought it was a K1!) + CB750K8
Re: ignition switch/wire problem
« Reply #9 on: September 10, 2009, 08:23:27 PM »
Who remembers 'Ogri' the Newcastle Brown beer swillin', bike ridin' cartoon character in 'Bike' ( British ) magazine ?....great forum name, mate.
Logged
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline Ogri

  • Thinks he's a
  • Hot Shot
  • ***
  • Posts: 331
Re: ignition switch/wire problem
« Reply #10 on: September 11, 2009, 01:46:56 AM »
Cheers matey, the only trouble is a lot of people read it as O R G I ...and think I'm some kind of Quagmire character  (Family Guy).
Logged

Offline HondanutRider

  • Ride often - ride long - ride SAFE...and be an
  • Expert
  • ****
  • Posts: 1,283
Re: ignition switch/wire problem
« Reply #11 on: September 11, 2009, 05:34:24 AM »
Somewhat same thing happened to me last night.

I was at a local big cruise night for motorcycles (must have been 1500 - 2000 bikes there, and only one CB350 Four) and when I went to leave - nothing.  Not a sign of power and the kick was doing nothing too.  So I called my wife and she came in the car with my VOM tester and I disconnected the ignition switch to see that power was indeed available there, and when I when I short the power spade to the BLACK it lights the indicators, etc.  So I conclude that my switch or wire from/to it is gone.  Making another round trip home I fab up a jumper cable for the ignition connector to do a hot-wire start.  Success, and I roar home with the hot-wired bike.

For those interested, the connector I accessed on my model is under the tank.  I hot-wired together the RED (power from battery) to BLACK (supplies power when switched on) and BROWN (to turn on rear marker light - it didn't show with headlight switch on unless powered as well).  With the connector apart/disconnected, the terminals inside are male spade mounts that I clipped onto with matching female spades on the end of my jumpers.
Logged
Pages: [1]   Go Up
« previous next »