The switch is at the base of the throttle housing. Remove the air cleaner housing. Look where the plate is that opens when you step on the gas, and lets air into the intake. I am not sure which side it is on your car, but look on either side. There is a pivot rod sort of thing that moves when you step on the gas pedal, and on the end of it is a switch. Sort of like a neutral start switch, only lots smaller. It is not repairable. Check it with an ohm meter to see if it works before you decide to replace it. I don't know if it is DIY. It is a piece of work to get to.

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1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)