how do you check the headlight relay ?

Still no headlight , can't figure out the problem . With the key "on" only the red and yellow wire has any voltage and only about 7-8 volts . With the bike running , only the white wire has power , 7-8 volts . I assume the black is ground and the blue goes to my dimmer switch .

I'm assuming the way the relay works is that the red/yellow wire gets the power from the fuse box and brings it into the relay , then only the white and the blue should get power on the way back out of the relay ? White goes to the diode block and blue to the dimmer switch ?
Shouldn't the red/yellow still have voltage after the bike is running ?
Why am I only getting 7-8 volt readings ?

One last thing . If I get the voltmeter or the leads too close to the engine the digital reading goes crazy all over the place . Is this the plugs messing up the meter ? Put on my old analog meter just to make sure the digital was Ok and it got the same readings

 

It is possible that the ElectroMagnetic Flux being generated by the coil wires is playing havoc with your digital. Is it a cheap piece? Odds are it is.
Best fix, get a quality meter and cover it with a foil shield. Ground the foil to the bike's case and you should be alright. Aluminum foil will work just fine. I've forgotten what type of bike we're looking at Lowlife, could you put it in your signature line? That way I'll know which wiring harness diagram to dig into so I can be of use.

 

Sorry , 82 650 maxim :wink:

 

The headlight should only come on if there is electricity being generated by the alternator. In theory this is so it only comes on after the bike starts but mine will come on while cranking if the battery has a good charge.

Time to start with the basics - meter your battery both parked and with the bike running. Should be above 13 parked and above 14 at 2K rpm. Then work your way through the fuse panel etc.

Your wiring diagram can be found here:

http://members.tripod.com/dave_jack/id39.htm

 

Thanks guys , seem to have found the problem

 

Right, ahem, I mean ride on bro!