View Full Version : Key Switch Testing

07-11-2014, 08:44 PM
Hello folks, long time no see.

My Be Last has a bit over 35k miles on it with used transmission and fresh piston/jug/top end. Well I thought I had it together and the bike was riding tits. Well messing around the other day I pop over a bump and the damn ignition/lights/system goes dead. I've checked the wiring and am being ridiculed and antagonized by this electrical problem. If I jump 12V+ from the key switch or accessories on the switch to the ignition, the relays click and the bike will crank with the ignition switch in the on position. I'm thinking the key switch failed because the three systems that don't work are all turned on with the key switch. Anyone have any idea how to check the key switch to make sure I have the problem cornered. Not getting power to the the ignition/lights/system fuse with the key in the on position.

Anyone in the Bay Area have a blast that I can test my ignition switch on? I have the switch off the bike and it would be a quick and easy test. The electrical part is only like 40$ from Harley but I need to be sure before throwing money down the rabbit hole.

Thanks for any tips or suggestions!

07-13-2014, 04:08 AM
Think I got it figured out, I'm pretty damn sure the key switch is toast. I'll try to asplain how the start system works for future reference.

The key switch has two hot inputs to with the key off, one from the accessories fuse and one from the key switch fuse both are linked. When you turn the key to the ON position it energizes the wire to terminal 86 of the system relay. This causes the relay to trigger which leads to energizing of the headlights/system/ignition. Basically the key switch controls the system relay. You can even jump start the bike this way, be sure and keep your bike locked up this would be ridiculously easy to steal if you were a crook or a fool.