Topic: All 4 turn signals come on at the same time? Headlight grounds?

[Chris Elliott]

I recently re-wired my bike with some new LED turn signals.  the bike came without turn signals so I had to figure everything out with a wiring diagram in a clymer manual.  I have double checked all my wiring but for some reason when i flip the left or right turn signal switch, all four signals light up instead of just 2 on the corresponding side.  Anyone have advice for me? Maybe its something to do with the LED signals I am using? 

Also... what grounds to the nuts on the inside of the headlight surround?  The wiring diagram doesn't show any grounds near the headlight except for the green wire in the harness that everything connects to.  Thanks in advance for your help..
-Chris E

[w1sa]

It sounds like each side of the blinker circuit is getting simultaneous power from the switch.
I'd be looking for bad/hacked wiring etc.

Maybe, start by opening the switch and verify that each wire/connection/joint is clean and secure and not bridging a connection to the other (static or when operated).
If the switch seems ok, remove the bulbs and use a meter to confirm separate continuities for each side and zero continuity between the left and right switch wires...i.e.
Test between left and right switch wires in the switch.......should be zero
From each switch wire to the corresponding circuit (power) delivery points at each blinker socket................should be good positive continuity
Then test for continuity between the left side switch wire and right side blinker sockets, and vice versa..........should be zero.
That should give you a good idea whether wiring from the switch to the blinker sockets is ok/correct.

If the bulbs are illuminating, earth/grounds should be ok.

[hijynx]

I have the same problem - on mine it's the switch. there are 3 wires coming from the switch - 1 input & 2 outputs to the directionals. when you activate the switch there should be continuity between 2 wires not 3. just out of curiosity do you have an aftermarket switch?

[Raul CB750K1]

I think that the problem lies in the blinker idiot light. It "sits" between both switch poles. When you turn the switch either way, it gives +12V to the corresponding set of blinkers, and also to the idiot light. Then, the idiot light is grounded through the other set of blinkers. The current running through it is high enough to lit the idiot light, but low enough to not lit the opposed set of blinkers.


My guess is that by using LED blinkers, that need much less current, the current through the idiot light is high enough to lit the blinkers.

How to diagnose? Remove -or disconnect- the blinker idiot light and try again. This time it should work as expected.

If you still want to go with the LED conversion, you will need to modify the wiring. Either use a blinker relay that have a separate connector for the idiot light, or rewire the idiot light, taking one of the poles to ground, and the other to both switch poles via diodes.

[Chris Elliott]

that sounds good enough to be true.. i will remove the bulb and check it out.. weird thing is though, that the idiot light doesn't turn on with the blinkers    I have a stock switch.

[CB500_k2]

This is a problem with converting blinker lights to LEDs when there is a single indicator light.  I had to use the technique which Raul described to keep all the blinkers from working at the same time and having an indicator light.  Just connect one of the indicator light leads to ground. Then solder the anode lead of a diode to each of the original wires went to the indicator (I used IN4001, 2 for $.99) , then connect the cathodes together and connect to the other lead of the indicator. This worked on a 2000 Ducati Monster and a 73 CB 500F.