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1981 honda GL500
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Discussion Starter · #1 · (Edited)
Hey all, 1981 gl500 bought stripped down to a cafe-ish bike. No fairings only a speedo headlight tail light and blinkers. Bike ran fine for 6 months, then Monday I went to start it, headlight came on then flickered off and wouldn't start. All wires are leading into the headlight housing which needed some tightening anyway so I rocked it up and down to get the light on, started it, then everything died. Went on like that back and forth for 20 mins before I decided to garage it and roll off to work. Fast forward to today and I've removed the aftermarket head lamp from the housing to see if I could see anything telling. Now obviously the bike has wires and connectors not connected to anything due to the strip down, but I can see anything wrong from the battery to the switch to the lights and starter. Any ideas?
Automotive tire Motor vehicle Automotive lighting Automotive exterior Bumper
edit: battery voltage is reading 12.33
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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When I experienced this on my CX, it was a broken wire in one of those taped bundles. As the bundle flexes, the ends make occasional contact.
I'd get a multimeter and a wiring diagram, and start verifying continuity in those wires. The likely culprit will be black (switched power) coming from the key switch.
 

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If your bike has the original style dog-bone main fuse, it is something to check.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Is that an aftermarket solenoid with integrated fuse holder?
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Maybe I should have said "the remains of an integrated fuse holder." You're going to want to replace that, or bypass it with an inline blade fuse.
You should probably trace the short that lead to that, too, unless it was just corrosion in the fuse contact.
 

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1981 honda GL500
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Discussion Starter · #9 ·
Maybe I should have said "the remains of an integrated fuse holder." You're going to want to replace that, or bypass it with an inline blade fuse.
You should probably trace the short that lead to that, too, unless it was just corrosion in the fuse contact.
I did replace the entire relay with a honda universal relay. But still no dice. I have no idea where to even start with tracing a short on such a harness. Should I disconnect it all and use a voltmeter?
 

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I did replace the entire relay with a honda universal relay. But still no dice. I have no idea where to even start with tracing a short on such a harness. Should I disconnect it all and use a voltmeter?
Are the symptoms still the same after replacing the starter relay and fuse? When you press the start button does the starter engage and turn the engine but the engine does not start.
If the fuse in the new starter relay doesn't blow then you probably do not have a short circuit, more likely an open connection.

Yes you should use a voltmeter but don't disconnect it all.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Start at battery positive, and work your way downstream, testing for voltage on each side of each connection or switch you encourage. You'll need a wiring diagram.
 

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1981 honda GL500
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Discussion Starter · #12 ·
Are the symptoms still the same after replacing the starter relay and fuse? When you press the start button does the starter engage and turn the engine but the engine does not start.
If the fuse in the new starter relay doesn't blow then you probably do not have a short circuit, more likely an open connection.

Yes you should use a voltmeter but don't disconnect it all.
No, nothing happens at all. The switch is set to start, the key in position and I press the start button and nothing. No click or whirring, nothing at all
 

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No, nothing happens at all. The switch is set to start, the key in position and I press the start button and nothing. No click or whirring, nothing at all
Is the bike in neutral and is the clutch handle pulled when you are trying to start the bike?
 

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Still no headlight with the key in the on position?
 

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Have you checked that the connector block for the key switch is properly inserted and making good contact?
 

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I would start with the kill switch circuit. It's relatively easy to diagnose. I had one fry right in the middle of the harness that goes from the switch to the headlight..
 

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1981 honda GL500
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Discussion Starter · #19 ·
Have you checked that the connector block for the key switch is properly inserted and making good contact?
I disconnected from the switch, repeated and the connection to the harness itself
 

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Discussion Starter · #20 ·
I would start with the kill switch circuit. It's relatively easy to diagnose. I had one fry right in the middle of the harness that goes from the switch to the headlight..
I've followed that down from the handlebar to the headlight and saw nothing telling of a short. Ill hit it tomorrow with the voltmeter
 
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