I'm having a problem with my motorbike not starting. The troubleshooting guide in the service manual asks me to check continuity on the neutral diode, saying there should be a 'small resistance' between the terminals, with the diode out of the circuit (no voltage).

 

I've measured 750 ohms - is that considered 'small' or is it broken?

Diode resistance should be near zero when connected correctly so your's is reading high & very little current will flow through it.

OK, many thanks...

Are you testing using the "diode" setting on your meter?

 

If so, that could be reading the 0.75 volt drop that is normal for a diode. A diode acts like an open circuit when the wrong way round in your circuit and a short circuit when the right way round. If you place a low watt lamp and diode in a series circuit from your battery, most of the battery voltage will appear across the lamp with a small 0.7 volt drop across the diode.

 

Hope that helps? (It's late and I should be in bed !)

 

Simon.

I was measuring resistance, not voltage. Turns out that 750 ohms was fine (according to Honda mechanic at the dealer). I put the diode back in, wiggled a few more connectors and suddenly it fired up - must have been a dodgy connection somewhere...

result

peter2b