Dai
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As Inge says... but it's a complete bugger to get at if the rubber cap is still intact because the wire has next to no slack in it. A possibly quicker way to check the warning light (if the tank is off and it sounds like it may be) is to ground the warning light wire. There should be a white socket forward-right and behind the radiator with a single brown-green wire to it. Disconnect the socket and ground the female side.
If the oil pressure light comes on then the circuit to the bulb is okay and the switch is possibly fubar'd.
Reconnect the socket and disconnect the wire from the oil pressure switch. It's underneath the oil/water pump at the front of the engine. Ground the wire.
If the warning light comes on then the switch is definitely fubar'd.
If the warning light does not come on then there's a possible break in the lower wire. It runs behind the HES cover (the T-shaped cover on the front of the engine). Unlikely.
Honestly - I'll bet you get to the pressure switch and the wire just falls off because the spade connector has corroded through.
You can statically test the temperature light but it's very difficult. Just running the bike at idle for five-ten minutes (which is the test for the fan) isn't going to work because the fan will kick in before over-temp is reached. You can try this just to ensure the fan is working and then ignore the over-temp light. OTOH, if the over-temp light comes on it will tell you that the fan's not working...
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Last edited by Dai on Sat Nov 14, 2015 9:57 am; edited 2 times in total
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1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500