[osgboater]

I have an 80hp Mercury that had intermittent starting problems before refusing to start altogether. There is not a sound when the key is turned to start. I suspected that the ignition switch was bad so I tested the switch according to the service manual. The manual has a table showing which wires should have continuity in various key positions. The table indicates the following:

OFF: BLK - BLK/YEL
RUN: RED - PUR
START: RED - YEL/RED, YEL/RED - PUR, RED - PUR
CHOKE: RED - YEL/BLK, RED - PUR, PUR - YEL/BLK

It doesn't explicitly state that all other connections should be open circuits. Here is what my tests show:

OFF: BLK - BLK/YEL, BLK - PUR
RUN: RED - PUR, BLK - RED, BLK - PUR
START: RED - YEL/RED, YEL/RED - PUR, RED - PUR, BLK - RED, BLK/YEL - RED
CHOKE: RED - YEL/BLK, RED - PUR, PUR - YEL/BLK

I assume that the extra BLK connections to RED and PUR are shorting things out but I would also expect a fuse to blow and open the circuit or some other indication of a problem.

Do the BLK-RED and BLK-PUR connections mean I have a bad key switch?

[bhile]

If I'm reading that correctly, yes you have a bad switch. You don't say what year the motor is so there may be a 20 amp fuse under the cowl that is blown too.

[osgboater]

Thanks Bill, I'll order the switch and go from there.