Reserve Lighting Device / Head Light Fuse

[79XS11F]

I just pepped my 79 restored bike for the weekend run and she fired up even with a weak battery but I have no head light. The head light fuse was blown and now continues to blow as soon as I fire the engine up.
Some history ....
The bike has a new old stock wiring harness on it that I installed this winter. The harness arrived in a factory sealed plastic bag and the harness is in mint condition. Soft and flexible with all connections showing no signs of storage corrosion. Last season before I put the bike away the instrument pod head light warning light was on and I had no high beam. I changed out the the head light bulb when I did the harness. The old bulb looked OK with both filaments looking good. This fuse blowing issue was not present last year so I put the old bulb back in but the fuse still blows.
So my question is ... Could a faulty reserve lighting device be blowing the headlight fuse?... or should I start my search looking somewhere else. All other lighting works properly.
Rob

[3Phase]

Rob,

Does it your '79 have the right-hand handlebar switch for the headlight?

If so, does it blow the headight fuse when you use the handlebar switch without starting the engine or does the headlight work until you start the engine?


Regards,

Scott

[79XS11F]

Rob,

Does it your '79 have the right-hand handlebar switch for the headlight?

If so, does it blow the headight fuse when you use the handlebar switch without starting the engine or does the headlight work until you start the engine?


Regards,

Scott

Hey Scott. Head light is off until the engine is running. Both right and left handlebar switches are also new old stock replacements.
Rob

[3Phase]

Hey Scott. Head light is off until the engine is running. Both right and left handlebar switches are also new old stock replacements.
Rob

So you do not have the Headlight ON/OFF switch on the right handlebar?

Hmm... <tapping teef> okay:

Disconnect the headlight.

Disconnect both instrument clusters to remove the cluster lights from the circuit.

Disconnect the front running lights (solid Blue wire bullet connectors in the headlight shell). Don't just remove the bulbs, disconnect the connectors.


See if the headlight fuse holds or blows when the bike starts without any lights hooked up.


What to check:

Left handlebar switch is shorted or grounded.

The striped Blue/Black wire from the right-hand handlebar switch connector shell up under the fuel tank and the Headlight Relay to the RLU is shorted or grounded.

The solid Blue wire to one of the running lights/instrument cluster lights is shorted or grounded.

The solid Blue wire for the auxiliary lighting connector in the headlight shell is shorted, grounded or connected to the Black wire connetor.

The RLU is bad.

Wrong/mislabeled wiring harness for your bike.


That's it for off the top of my head, Rob!


Regards,

Scott

[79XS11F]

OK this is what I have with the fuse removed or blown with No head light hooked up, main switch key turned on and the kill switch in the run position.
I have front instrument pod lights ON, Front marker lights ON, Tail light ON, Brake lights working from both brake light source switches, Both right and left turn signal lights working at both the front and back of the bike. NO speedo or tack lights but I am not sure if they are activated only when the engine is running as is the case with the head light. tested ... as soon as the key is turned to the on position the fuse blows.
Rob

[79XS11F]

Can someone who owns a 78 or 79 standard model tell me if the instrument lights are suppose to be on or off with the key turned to the on position and the engine not running. I am thinking that the issue is ether the reserve lighting device or the headlight relay.
Rob

[79XS11F]

According to the manual the first stop out of the fuse box on the head light circuit is the head light relay followed by the meter lights and the reserve lighting device.
I'll start with the relay because I have no meter lights .... and I'm pretty sure the meter lights and fuel gage are suppose to be on without the engine running when the main switch is on.
Rob

[DiverRay]

Rob is correct, the headlamp should only come on AFTER the engine starts. The rest of the lights will be on with the switch. You can disconnect the RLU, and try it again.The next thing to look at is the ground connections, AND the headlight circuit. I would use a VOM to see if any of the headlamp wires are grounded. Do this with the headlight DISCONNECTED, as the headlamp has a LOW resistance between the filiment and the ground.
There IS a thread that talks about what wires to jump to bypass the RLU.

[79XS11F]

Given that the meter lights are not coming on with the main switch, and they are the first stop out of the relay, I'm thinking the relay is grounding out as in TOAST. I will be tracking this issue down tomorrow after work and post what I discover.
Rob

[3Phase]

as soon as the key is turned to the on position the fuse blows.

Sorry, Rob, the new piston rings for my bike arrived today. I'm cleaning parts and surfing the 'net while I work.

If the headlight fuse blows when you turn on the key, before starting the engine, the striped Red/Yellow wire is shorted somewhere between the fuse box, the headlight relay and the right-hand handlebar switch connector.

There is a remote possibility that the headlight relay itself is bad or connected backwards.


Regards,

Scott

[oseaghdha]

The instrument lights should only come on with the headlight.

[79XS11F]

Unbelievable ... I just lost 2 hours driving around to find only 3 10 amp glass fuses. i went to 2 CTC stores, a auto + store, 2 Dollar stores and NAPA with no luck. NO STOCK GRRRRRRR ... Anyway I found 1 pack of 3 at The Source store.
Unbelievable


Rob

[79XS11F]

Got it ....

OK disconnected both the relay and reserve light device one at a time and fuse was still being blown. Disconnected all in pod connection and fuse still blows ... Disconnected all handlebar wires and in pod wires and hooked them back up one at a time until the fuse went. It was the right side handlebar switch lead. Turns out that this 2H7 numbered switch has an additional black wire in the block connector that used to be blank. on the harness that blank used to go to a hot red / white wire so with that additional black GROUND wire in the switch it was putting red/white directly to ground... So I cut it off with great pleasure :-)

On a different note all the lighting, horn, head light are much brighter / louder with this NOS harness. Even the tack now has no bounce and the fuel gage moves to full ASAP :-)
Rob

[3Phase]

Turns out that this 2H7 numbered switch has an additional black wire in the block connector that used to be blank. on the harness that blank used to go to a hot red / white wire so with that additional black GROUND wire in the switch it was putting red/white directly to ground... So I cut it off with great pleasure :-)

On a different note all the lighting, horn, head light are much brighter / louder with this NOS harness. Even the tack now has no bounce and the fuel gage moves to full ASAP :-)
Rob

Way to go, Rob!

So, apparently, there is a unlabeled, unmentioned and mispositioned Black (ground) wire on some right-hand controls. That is a very good thing to know, thank you!


Regards,

Scott

[79XS11F]

Well I don't know how many models the 2H7 parts were used on but with no difference between this new switch and the old one I can't see any use for this black wire. This black wire was also only about 1/2 the DIA of the other wires in the block connector. In any case that wire was putting the head light circuit directly to ground when plugged into the main harness. I guess what it means is that if your changing out your switches for new old stock or used ones ... check them closely at the block connector for match to what is coming off the bike.
Rob