Re: ’93 15hp electric start issue

[frankr]

quote johnyrude200:

To follow up – just swapped out the original switch and it fixed the problem. So while the multimeter was showing 12V at the end of the switch lead, the original switch must have been corroded/broken down/burnt out because it could not allow enough amps through the connection for the starter to get what it needed.

So even though the switch tested fine, that doesn’t mean it was OK.

Yep, what you did was what’s known as a voltage drop test. You were testing the voltage drop across the circuit between the battery and switch output terminal. The fact that there was such a drastic voltage drop when you activated the switch while connected to the starter motor indicates there was a high resistance in that circuit, in this case the switch.

Voltage drop tests are a very useful diagnostic procedures. Too bad so few people understand them.