No Power to Headlight, help!

My headlight is not working. Im trying to make sense with the wiring diagram but im totally clueless. My headlight bucket is a mess, therre is a few bullet connectors missing connections, a few are black, one is red, and one is light blue.
I checked for power at the headlight with a multimeter and there is none. I traced the wire to the lefthandle bar high/low switch. There is 2 wires that feed to the headlight, and a bluewire with a black stripe, which had no power. I traced the blue/black wire to the left side panel, under the ignitor, where it plugs into what i think is a relay? There are 4 wires into a small box, on is red and has power, one is black and the two others are getting no power.

Any advice on how to track down this problem would be greatly appreciated! Thanks,
DG

 

Howdy DG,
Could you fill us in and perhaps post what model and year we are discussing here? It would take a lot of the "hunt and peck" out of troubleshooting.
Thanks.

 

Are your gauge lights working? It could be a fuse in the fuse box or possible a stuck starter switch. My bike had the same problem and it turned out that the starter switch was stuck in a little. I just pulled it out and everything worked just fine after that.

 

Oops, its a 1982 Maxim 650. I checked the fuses, Ill try the starter switch, thanks

 

Can you post a copy of your wiring digram? I'll track it back and give you a troubleshooting guide if I can. Don't forget to include the key so we can see what's what.

Ignore the colour of the bullet connectors, it's the wire colours that matter.. If someone's changed the wires around and the colours don't match, do yourself a favour and attach a lable with the correct colours.. it'll make your life easier now and in the future.

 

Yeah, I had a short in the start switch that killed the
head light. The bike still started fine.
Easy fix once you locate the prob.

 

thanks! I tried taking the start button apart and then tested the headlight and still no power. Heres a wiring diagram i found,
http://xjdiagrams.thundervalleypower.co ... ag/d7a.jpg
http://xjdiagrams.thundervalleypower.co ... ag/d7b.jpg
http://xjdiagrams.thundervalleypower.co ... iag/d8.jpg

 

are your tach and speedo lamps working? looks like they are on the same circuit...

 

the tach is working, the speedo light comes and off intermittently,.

 

ok, that tells me (assuming the wiring diagram provided is correct for your bike) that the relay is fine since they both run off the same wire from the relay as the headlight. the intermittent speedo light indicates a poor connection and likely the same cause for the dead headlight. trace the blue wires from the relay checking/cleaning connectors along the way and you should find a bad one somewhere along the line. sometimes the wire will come out of the crimp connection so watch out for those too. i would guess that those connectors are probably inside the headlight housing btw (location notorious for getting wet/rusty/corroded).

good luck

Trev

 

On the XJ650 the headlight circuit is not powered until the headlamp relay detects output from the alternator. What this means is the motorcycle must be running and the charging system in good order before the headlight will work. You're wasting your time looking for voltage unless the motorcycle has been started.

The order you should use for diagnosis:

Verify headlamp fuse is good (Verify holder is good too).
Check that charging system is producing 14+ volts at 2Krpm.
Check for +12V in and out of the headlamp relay (motorcycle running)
Then go after switches and stuff in the headlamp bucket.

 

thanks! When i test exposed metal on the blue wire coming out of the relay there is no power.
Would it be possible to just connect the red wire coming into the relay to the blue wire, ground it somehow to the frame and see if the headlight works, as a way to test the relay? Or could I ground the wires that go into the headlight with some kind of makeshift ground to see if maybe its a loose ground connection somewhere? Thanks again for your advice,
DG

 

interesting... how are your tach/speedo lights getting power then? should be the same source, no?

 

good point, its possible that the headlight power is flicking on and off, i dont have one connected i took it off to test the wires. Ill start over and test the blue wire coming out of the relay with the bike running. Thanks for the tips!

 

They are not the same source on the XJ650.

Did you do the charging system test?

 

ok, that may be the case, but then why does the xj650 wiring diagram posted above show them connecting to the headlight wire?

 

Ok, i did the test and I got around 14 volts at 2k.
Also, i tested the relay while the bike was running. While running the blue wire that goes to the headlight still had no power. The red wire which has power when the bike is not running had no power while running. The white wire Did have power.
The fuse/housing are fine.
What does this mean? Thanks!

 

the red wire loses power when you start the engine? this is the red wire that goes to the headlight relay? and you say the fuse/panel are good? is there power at the fuse? do the signal lights work?

 

I haven't read much otf the above, I'm better at reading wiring diagrams than words...

The wiring diagram posted shows only Light Green, yellow and Black wires going into the headlamp (21), so it's not for the same bike if you don't have those colours.

According to the diagram posted, (because it's the only one I have) the Black wire goes to earth. You can basically ignore that.. Just test that it has a connection.

The yellow wire goes to the Hi beam, the light green goes to low beam.

From there, they have a common blue/black wire that goes to the Headlamp relay.

The headlamp relay had four wires..
Blue/black (as above)
Black - Goes to earth
Red/Yellow - Which goes to the headlamp fuse
White - which goes to the diode block and will be responsible for providing switch for the headlamp relay.

The Headlamp fuse goes to a grey wire that goes the the bar switch, and then onto a red wire that goes to the battery via the main fuse.

OK, from this, work your way back until you get to a point where you have power on the inbound wire, but not on the outbound wire, and you've found your fault.

My guess would be that the Diode block is not providing a switch for the headlamp relay, so when you start the engine, there's no power coming from the blue/black wire You can test this by testing for a voltage on the white wire going into the headlamp relay. If you get no voltage on this when the engine is running, then my guess is that your diode block is kaput. The switched signal for a running engine going into the diode block appears to be the other white wire that originates at the alternator. If this is providing an A/C current, and other things are switched on..

You can try applying a voltage from a (fused) 12v source (at your own risk) onto the white inlet on the headlamp relay. If the headlamp then comes on, you've proved that the headlamp relay is in working order, so the problem must be the signal from the diode block.

Here's where trouble shooting gets a bit more tricky.. The diode block is a black box.. I can only guess what's in there from the wires going in and out.. But the purpose of the diode block is to take the A/C current from the alternator, and make it into a D/C current.. I would assume that the signal to the headlamp relay is a D/C signal, but without a working example, I can't tell.. But my guess is that a diode has blown somewhere in that diode block, and you're no longer getting an outward signal (or the white wire has come loose....)

Anyway, that's my 2 centimes worth.. Hope it helps.

 

hey swiss, i think djg's last post indicated that the white wire from the diode block to the relay already does have power but the red wire that the relay (presumably) switches to the blue wire does not. this indicates the diode block is functioning - and the relay may also be good but power is not even getting that far when running. i agree that the best course of action is to trace the red power wire back through the fuse and beyond to find the problem.

good luck!

Trev