Headlamp refuses to come on

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Splexin

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I briefly posted about my issue but decided to start my own thread..........

I bought and installed brand new OEM wiring harness for my '80 Special II. I also bought and installed a brand new OEM clutch-side switch.

After connecting everything I start up the bike and the indicator lights, blinkers, brake/tail lights work GREAT (brighter than before I think).........but the headlamp does not come on at all (high beam or low)!!! I cannot locate my camera to take a picture of my connections, but I plugged yellow-harness and yellow-switch into the yellow-headlamp, black-headlamp to black-harness, and green-switch to green-headlamp. Isn't that correct??

What's bugging me is that everything on the bike functions 100%, including horn. So I don't think I plugged anything in wrong. Bike starts right up and runs smoothly. I did the wrench-slap test and alternator seems fine (brushes fairly new too) so I don't think my charging system is an issue. Fuses are fine and new fuse box with new wiring harness. I have bypassed the RLU previously, now I'm wondering the safety relay could be the problem? What else could it be??? I'm pretty sure the bulb is not burnt out.
 
i would first check the connections inside your handlebar switch. i had a couple broke connections a couple weeks ago that prevented my turn signals from working but horn, lights, everything else worked fine.

you could also try bypassing your safety relay. run a jumper from the blue/black to red/yellow connections at the safety relay.

good luck
 
Splexin said:
I briefly posted about my issue but decided to start my own thread..........

I bought and installed brand new OEM wiring harness for my '80 Special II. I also bought and installed a brand new OEM clutch-side switch.

After connecting everything I start up the bike and the indicator lights, blinkers, brake/tail lights work GREAT (brighter than before I think).........but the headlamp does not come on at all (high beam or low)!!! I cannot locate my camera to take a picture of my connections, but I plugged yellow-harness and yellow-switch into the yellow-headlamp, black-headlamp to black-harness, and green-switch to green-headlamp. Isn't that correct??

What's bugging me is that everything on the bike functions 100%, including horn. So I don't think I plugged anything in wrong. Bike starts right up and runs smoothly. I did the wrench-slap test and alternator seems fine (brushes fairly new too) so I don't think my charging system is an issue. Fuses are fine and new fuse box with new wiring harness. I have bypassed the RLU previously, now I'm wondering the safety relay could be the problem? What else could it be??? I'm pretty sure the bulb is not burnt out.
Click to expand...

The Safety Relay is the switch that turns on your headlight. In order to operate that switch, the yellow wire that comes from the centre winding connection of the alternator, has to be connected to the SR coil. Is that wire connected?

Use a VOM set to AC volts (20 volt scale) to measure the AC voltage at the yellow wire terminal of the Safety Relay. You should measure about 14 volts AC from that terminal to ground (engine idling). What voltage do you measure?
 
XSJoel said:
I would start by jumping the safety relay.
Click to expand...

Didn't work :(

I think something is not connected properly with the headlamp. Everything else works......just hooked up VOM to battery and volts increase with throttle so charging system seems to be working.....regardless of that blinkers, horn, tailight, indicators, fuses, everything WORKS bright not dim.......and I've jumped safety relay and headlamp still don't work.....does anybody have a picture of stock headlamp???

Furthermore is there a way to test headlamp independently?
 
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Measure resistance between the blades on the back of the bulb. The ground blade, which i believe is the one turned sideways, should have continuity with both the others, and the parallel blades should not have continuity with each other.
If your bulb is good, you can back probe into the connector. The ground should have a very low resistance path to the point where the ground wire from your battery attaches to the motor and/or frame. with the safety switch defeated, probe the other two blades with a test light and a reliable ground and see if you get anything, hi beam or low beam from either plug. If you don't get ground and voltage to the back of a good light bulb, she ain't gonna light up.

Since you changed the clutch-side switch, make sure it is pushing the plunger in far enough to close the switch when it's up, and make sure it opens when the stand is down.
 
jd750ace said:
Measure resistance between the blades on the back of the bulb. The ground blade, which i believe is the one turned sideways, should have continuity with both the others, and the parallel blades should not have continuity with each other.
If your bulb is good, you can back probe into the connector. The ground should have a very low resistance path to the point where the ground wire from your battery attaches to the motor and/or frame. with the safety switch defeated, probe the other two blades with a test light and a reliable ground and see if you get anything, hi beam or low beam from either plug. If you don't get ground and voltage to the back of a good light bulb, she ain't gonna light up.
Click to expand...
Okay I just did this but I am getting no reading. I only get a reading if I put both leads on the same blade. Does this mean the bulb is bad? This is a sealed unit.
jd750ace said:
Since you changed the clutch-side switch, make sure it is pushing the plunger in far enough to close the switch when it's up, and make sure it opens when the stand is down.
Click to expand...
Can you please clarify? The switch only controls hi-lo beam right? If I press it up the hi-beam indicator light comes on (and headlamp hi-beam is supposed to come on). If I press it down the indicator light goes off and the lo-beam resumes (supposed to, but neither beams are coming on).
 
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After you start the bike check to see if you're getting voltagejto the headlight socket. You can directly wire your headlamp to a 12v dc source to see if its working.
 
hmusket said:
After you start the bike check to see if you're getting voltagejto the headlight socket.
Click to expand...

OK so I connected the tester to a blinker positive and ground (just to make sure my tester is working properly), turned on the blinker and the tester displayed the voltage.

I then connected it to the yellow-split wire coming out of the headlamp and then to a ground, turned on the bike, and got no voltage. So what does this mean? The problem is the yellow wire on the wire harness?
 
OK I've connected the headlight to several power sources and still get nothing. No continuity on any of the bulb's blades either when I test it with leads of separate blades. So I'm going to risk $10 and buy a new bulb. At least then I will rule out another possibility. If that doesn't solve the problem then I will know for sure it's the wire.
 
Splexin said:
OK so I connected the tester to a blinker positive and ground (just to make sure my tester is working properly), turned on the blinker and the tester displayed the voltage.

I then connected it to the yellow-split wire coming out of the headlamp and then to a ground, turned on the bike, and got no voltage. So what does this mean? The problem is the yellow wire on the wire harness?
Click to expand...

did you start the bike or just turn it 'on'? if you didn't start the bike i believe the safety relay is doing it's job and not turning on the light until the bike is running...
 
deadchef said:
did you start the bike or just turn it 'on'? if you didn't start the bike i believe the safety relay is doing it's job and not turning on the light until the bike is running...
Click to expand...

Started the bike. Either way, I've jumped the relay so that means the light should come on when I turn the key right?
 
Splexin said:
Started the bike. Either way, I've jumped the relay so that means the light should come on when I turn the key right?
Click to expand...

if you have the relay jumped then yes, it will come on with the bike just turned 'on'.

if you tried hooking up the bulb straight to a 12v battery and it didn't light up then it sounds like you just have a bad bulb. it's funny how some problems can have the most obvious solutions.
 
deadchef said:
if you have the relay jumped then yes, it will come on with the bike just turned 'on'.

if you tried hooking up the bulb straight to a 12v battery and it didn't light up then it sounds like you just have a bad bulb. it's funny how some problems can have the most obvious solutions.
Click to expand...

I'm really hoping it's the bulb. I've pretty much gone clinically insane trying to figure out which wire is connected improperly. The whole point of me getting a new switch and wiring harness was to clear up any phantom issues with my blinkers and headlamp so I can pass inspection next month. Now, everything works.....except the damn headlight!!!! :banghead:

:laugh:
 
Splexin said:
I'm really hoping it's the bulb. I've pretty much gone clinically insane trying to figure out which wire is connected improperly. The whole point of me getting a new switch and wiring harness was to clear up any phantom issues with my blinkers and headlamp so I can pass inspection next month. Now, everything works.....except the damn headlight!!!! :banghead:

:laugh:
Click to expand...

gotta love old bikes! :laugh::laugh:
 
Your bulb is shot if no two blades show continuity. One is ground, one is the high beam filament, and the other is the low beam filament. If you can't read continuity between 2 blades, there is no complete circuit.
 
jd750ace said:
Your bulb is shot if no two blades show continuity. One is ground, one is the high beam filament, and the other is the low beam filament. If you can't read continuity between 2 blades, there is no complete circuit.
Click to expand...

PRAISE THE MOTORCYCLE GODS!!!! :D That's what it was.....ordered a new bulb, plugged it up and voila.....LET THERE BE LIGHT! :thumbsup:

Wish I had known about the continuity test-trick before, would've saved me so much trouble. I was starting to get worried that I would have to yank the whole harness to find a loose end :laugh: Next time I will just check the bulb first :bike:

Thanks for your help
 

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