Topic: SEE UPDATE IN THE TEXT STRING 71 CB500 starter engages when I turn key on

[Llanier44]

Hi all. I’m working to get my 71 CB500 back on the road. I’m going through the electrical wiring and circuits and have run into an issue. When I got the bike the PO had changed out the left and right handlebar switches (from Common Motor I think).  It has an aftermarket key switch and solenoid. Battery is 100%, main ground is good, wiring harness is good (I’ve tested continuity through all the ignition related wiring and switches).  Issue is that when I turn the key to the first position, the starter immediately engages (kill switch in off position) without me pressing the starter button. As indicated, the starter button (left hand controls) is new. Has someone had this problem? Suggestions to troubleshoot?  I’m just getting over a life-saving operation and finally getting back to my project, thank God. Appreciate any help.

[scottly]

The stock starter switch has a yellow/red wire, that is connected through the harness to the starter solenoid. When the button is pressed, it connects the y/r wire to ground. The other small solenoid wire is black, which is "hot" (+12v) when the key is on, so when the y/r is grounded at the switch, current flows through the electro-magnet coil in the solenoid which causes the heavy switch of the solenoid to close, operating the starter. If you disconnect the y/r wire from the solenoid and measure the resistance to ground with an ohmmeter, it should read open until the button is pressed, when it should switch to a low ohms reading. I suspect you will have continuity to ground without the button pressed, and need to start looking at the switch and it's wiring.
Was it like this since you've had the bike, or is this a new development?   

[bryanj]

Starter button is NOT on LH side control

[scottly]

As indicated, the starter button (left hand controls) is new.

The starter button should be on the right side??

[Llanier44]

Thanks for the replies…and accept my apologies for posting on this topic a second time. I simply forgot I had sought advice on this once before and got some great responses. Please don’t feel the need to post more advice on this topic until I try all the things suggested before. Thank you again

[scottly]

No worries.

[Llanier44]

So, problem fixed. Thought I’d post the fix for those who decide to use aftermarket handlebar controls. Dr Frankenstein sent me a PM with the fix (much thanks!).  Here’s the likely problem in the aftermarket right hand control switch assembly: the yellow wire with red stripe is sometimes routed incorrectly, which causes it to fray and then short. I disassembled it and found my wire frayed through the sheath. There is a little metal bracket that secures the wire loom in the right place to keep it out of the way when putting the controls on the handlebar. My yellow/red wire was run on top of that little bracket -bad. I taped up the bare wire and rerouted UNDER the bracket - keeping it from getting rubbed by the throttle operation. It’s a simple fix- you can reroute the wire without disconnecting it. So…one problem solved thanks to this community. Hope this helps someone else. Have a great day.