Electrical Troubleshooting ‘79 GL1000

[77Gowing]

Matt,
I recalled something from when I was connecting up my turns and running lights.
I also had a temporary problem when the headlight bucket was allowed to hang free while I figured out how to stuff the bucket with the wires. It turns out that bucket ground goes through the bucket bolts and the ears that attach to the forks. I tested this idea by leaving the bucket unattached and use a simple test lead from bucket to the forks or chassis. With this temp ground I was able to verify all my electrics worked. And as a last check, I removed the temp ground lead and thus either my turns would not function properly or my running. I dont recall which. But I was able to replicate the probkem at will. Once the bucket is bolted to the ears the ground path is quite substantial.
As I recall one end clipped to the green spade connection at the back of the bucket, the other end is placed on any good conducting part of the chassis.

Best of luck.

[Shadowjack]

If you did not replace the various wires with different colors, or plug different colors together, someone else has molested it already. Do NOT trust any colored wires to be part of their original purpose if they have aftermarket connectors on them. Honda never plugged two wires of different colors together. And Honda grounds are always green. Always. Very bad idea to make some power circuit out of green wire.

[Sidecar Bob]

Most bikes with metal headlight shells have a ground lug inside but it is for connecting the shell to ground through the green wire in the wiring harness, NOT for grounding anything else to.

If the signals are only working when you connect the headlight shell to the ears you have grounded the signals to the shell.
DON'T DO THAT!!!
I'll say it again: DO NOT use the frame or bodywork of any vehicle for the return electrical path (including the headlight shell of a motorcycle), especially if doing so would mean that current would need to flow through a bearing to get back to the battery.

All return circuits MUST be connected to the green (ground) wire in the wiring harness.

[77Gowing]

Most bikes with metal headlight shells have a ground lug inside but it is for connecting the shell to ground through the green wire in the wiring harness, NOT for grounding anything else to.

If the signals are only working when you connect the headlight shell to the ears you have grounded the signals to the shell.

DON'T DO THAT!!!
I'll say it again: DO NOT use the frame or bodywork of any vehicle for the return electrical path (including the headlight shell of a motorcycle), especially if doing so would mean that current would need to flow through a bearing to get back to the battery.

All return circuits MUST be connected to the green (ground) wire in the wiring harness.

Bob, yes the lug inside is the ground, but unless the bucket is attached to the ears the ground floats. Since my bucket was unattached while I was working on it, the ground ended up floating. This is why I use a temporary connection while I was working on the bikes wires. Once the bucket was reattached to the ears the temp connection was removed.
My problem started by having the bucket unattached and is how I realised that the path from the shell lug for ground goes through the bolts to the chassis. And is why during this operation the turns did not work properly.
You are correct about the head bearings btw.
So, except for when the shell was floating, I did not use the temporay test lead ground. This was carefully tested several times to my satisfaction that the ground path is from lug to shell, shell to mounting bolts, bolts to headlamp ears.

[MattMcCoy]

Thanks, guys. The gentleman that this bike belonged to enjoyed it with/without a fairing. After 42 years, the wiring is pretty good and has the expected modifications to accommodate doing so. My very basic understanding of electrical work is probably making it out to be worse than reality. I appreciate everyone’s generosity with their time and help.

Here’s where I am:

-Aftermarket OEM-like turn signals (red, black, black/white). I believe they are K&L.

-Turn signals work (orange and light blue to red).

-Idiot lights work

-Turn buzzer works

-Bucket is plastic

-Extra orange and light blue wire from harness in the bucket (female connectors) go to rear turns. Probably added to accommodate trunk/bags or additional signal lights at one time.

-Have an orange/white running light wire in the bucket that I can run wire into back of connector (running light works).

-Do not have a light blue/white running light wire in the bucket.

-I can jump running light wire to distribution block and push into back of orange/white and light blue/white connector and get running lights.

-Works, but one running light is brighter than the other. I can switch running-light wires and move brighter side to the other signal.

It’s my understanding that the running lights should be dim and flash brighter when activated.

I hope that makes sense.

[Sidecar Bob]

Bob, yes the lug inside is the ground, but unless the bucket is attached to the ears the ground floats.

As I said, the lug is for grounding the shell itself, not for using it as a ground point for anything else. It is supposed to be connected to the green wire in the harness and that's all.

The light blue/white and orange/white wires should both come from the left hand handlebar switch assembly. If you have the orange/white follow it back to where it comes out of the cable from the switch assembly and you should find the light blue/white.

Some basics:
As you know, the original front turn signals on these bikes (& most Hondas of the same era) function as both running lights and turn signals. They have the same dual filament type 1157 bulbs that are used in the tail/brake light. The lower power filaments are used as marker lights and are on normally. When you switch a turn signal on the low filament in that bulb is turned off and the high power filament flashes so that you have BRIGHT-OFF-BRIGHT-OFF (if the low filament was left on you would have BRIGHT-DIM-BRIGHT-DIM - legalities aside this would be harder to discern as a signal in some conditions).
Amber marker lights are only allowed at the front of a vehicle so the rear turn signals do not have marker lights.

You cannot connect the right running light to the wire for the left one because if you did the right marker would be off when the left is flashing but still on when the right is flashing.

[MattMcCoy]

Running lights (orange/white, light blue/white) run from turn signal control to harness in distribution block under left shelter. I’ll cut away more of the main wire harness to find where the orange/white in bucket emanates from, to see if I can find the light blue/white.

Why does one running light appear brighter when I jump from running light wire on turn signal to appropriate wires connected at distribution?

[Sidecar Bob]

Distribution block? Do you mean the 3 way female bullet connector on the end of the green (ground) wire or is there something we haven't seen?

If you mean the connector on the ground wire you probably have something connected wrong. Without any information from the supplier of the signals (I looked at K&L's website and it says nothing about which wire is which), I would start by disconnecting one of the signals and testing to see which wire is which. With nothing to go by but wire colours I think I would start by connecting the black wire to the battery's negative and the red to its positive and see what happens. If, as I suspect will happen, it lights up brightly I would next disconnect the red from the battery and try the black/white expecting the signal to light less brightly.
If I am right about that you need to connect the signal's black wire to the bike's green, the signal's red to the bike's orange or light blue and the signal's black/white to the bike's orange/white or light blue/white.
If my guess about which wire is which is wrong you need to either experiment until you find out which wire is which or contact the place you got them from about which wire is which.

More basics: Assuming that these signals have bulbs in them the bulbs should be like the drawing below (LEDs are completely different). One end of each filament is connected to a terminal on the end of the bulb and the other is connected to the shell of the bulb's base (common connection) and the 3 wires are connected to the terminals and the shell. If you have managed to connect the wire for the bright filament to positive and the wire for the dim filament to negative (green ground wire with the 3 way connector) current will flow through the bright filament to the bulb's common connection and then through the other filament to the green wire and it will light up. And if you then touch the wire from the bulb's common connection to the green wire the current will flow through the bright filament to ground (without having to go through the dim filament) and it will light up more brightly.

Dual filament bayonet bulb.gif (37.71 KiB) Viewed 226 times

If you have a multimeter you can remove the lens and bulb and use the meter's ohmmeter function to figure out which wire is connected to the side of the lamp base. Once you know that you can re-assemble the signal, connect the wire from the side of the lamp base to the bike's green wire and the signal's other wires to the bike's signal and marker wires and see what happens.
If it is dimmer when the signal is off and brighter when flashing you have it connected correctly.
If it is brighter when the signal is off and dimmer when flashing leave the common connection to the bike's green wire alone and reverse the other 2 wires.

[MattMcCoy]

All good stuff, Bob—much appreciated. The distribution block I mentioned is located under the left shelter and accepts multiple connectors from the wiring harness. It’s labeled coupler holder or something similar on CMSNL.



I opened the turn signal and verified that the common ground attached to the bulb housing is the black/white wire. I’ll try both red and black to determine the dim filament (running light) and the brighter filament (turn signal).

[MattMcCoy]

We did it, guys. When I was buttoning up the turn signal housing and twisted the bulb back in, the socket disk with the two tabs that make contact with the dim/bright filaments spun with it. I rotated and re-aligned the tabs to correspond to the right location on the bulb and now running lights are dim and flashers are bright. Instrument lights, runners, and turns all work correctly now. Looking at the schematic and if I’m reading correctly; when switched to park, brake light, accessory terminal, and starter should be powered—instrument lights should be off. Correct?

[Sidecar Bob]

Just the tail light and the accessory terminals (& that brown wire at the front), nothing else, including the starter. There will be power to the solenoid but it can't get to the starter motor unless the solenoid is energized and the key needs to be on for that...

[MattMcCoy]

Appreciate it, Bob.

[77Gowing]

Distribution block? Do you mean the 3 way female bullet connector on the end of the green (ground) wire or is there something we haven't seen?

If you mean the connector on the ground wire you probably have something connected wrong. Without any information from the supplier of the signals (I looked at K&L's website and it says nothing about which wire is which), I would start by disconnecting one of the signals and testing to see which wire is which. With nothing to go by but wire colours I think I would start by connecting the black wire to the battery's negative and the red to its positive and see what happens. If, as I suspect will happen, it lights up brightly I would next disconnect the red from the battery and try the black/white expecting the signal to light less brightly.
If I am right about that you need to connect the signal's black wire to the bike's green, the signal's red to the bike's orange or light blue and the signal's black/white to the bike's orange/white or light blue/white.
If my guess about which wire is which is wrong you need to either experiment until you find out which wire is which or contact the place you got them from about which wire is which.

More basics: Assuming that these signals have bulbs in them the bulbs should be like the drawing below (LEDs are completely different). One end of each filament is connected to a terminal on the end of the bulb and the other is connected to the shell of the bulb's base (common connection) and the 3 wires are connected to the terminals and the shell. If you have managed to connect the wire for the bright filament to positive and the wire for the dim filament to negative (green ground wire with the 3 way connector) current will flow through the bright filament to the bulb's common connection and then through the other filament to the green wire and it will light up. And if you then touch the wire from the bulb's common connection to the green wire the current will flow through the bright filament to ground (without having to go through the dim filament) and it will light up more brightly.
Dual filament bayonet bulb.gif

If you have a multimeter you can remove the lens and bulb and use the meter's ohmmeter function to figure out which wire is connected to the side of the lamp base. Once you know that you can re-assemble the signal, connect the wire from the side of the lamp base to the bike's green wire and the signal's other wires to the bike's signal and marker wires and see what happens.
If it is dimmer when the signal is off and brighter when flashing you have it connected correctly.
If it is brighter when the signal is off and dimmer when flashing leave the common connection to the bike's green wire alone and reverse the other 2 wires.

Uhoh! Bob, you got me to think of something with your color diagram of the two filiment bulb. I note that one filiment is smaller than the other one. I postulate that the larger filiment has a higher R value than the shorter filiment. I conclude that the shorter filiment has less resistance and therefore conducts more current than the larger filiment and thus has a higher wattage and likely glows the brightest. I may be wrong, but I assume the smaller filiment would be the flash for turn, and the larger dimmer filiment would be running lights. So, to sort out which filiment is brighter, a person can take the OEM, Or aftermarket signal assembly and record the Resistance in ohms of each colored wire to bulb common on the bulb shell. This assumes the filiments have identical ohms/foot characteristics. I once bought a wire sample of 1 foot that was rated at 25 ohms/ft in order to make a special inductive coil for a 1942 Gasoline/electric tank.
Anyway, I believe the ohmic values a person could record will exlain which filiment does what and point to the correct OEM wire color to connect to.
Please comment up or down if you please.

Thanks Bob.
Ps. You are indeed very knowledgeable and capable, but I dont think you understood the precise meaning of my discussion where I used a temporary ground. No matter, it worked for me and no head bearings or kittens were damaged.

[Sidecar Bob]

The formula for electrical power is P = E x I where P is power (watts), E is voltage (volts) and I is current (amps).
The formula for current is I = E ÷ R where P and I are as above and R is resistance (ohms).

When you crunch them together you get P = E² ÷ R

From this we can tell that for any specific voltage a lower the resistance will produce more power so the filament that has lower resistance will be the higher power (= brighter) one.

BTW: The drawing I posted is only intended to illustrate how the filaments are connected to thee lamp base so don't try to figure out which filament is which from it. To start with, the terminals and the indexing pins on an 1157 are at right angles to each other (as I said, it is only for illustration).
Also, from what I can find online (& remember from long ago when any of the vehicles we have had incandescent bulbs), the actual filaments in an 1157 type (or similar) bulb are generally about the same length but they are made of different thicknesses of wire; The thicker wire will have lower resistance than the thinner wire so the thinner filament will be the lower power (dimmer) one and the thicker filament will be the higher power (brighter) one.
The wires that support the filaments (which shouldn't have a measurable effect on the power) are usually different lengths and from what I can tell after looking at a lot of pictures of 1157 bulbs just now the bright filament is almost always on the shorter support wires but I wouldn't go by that.

And, of course, LED lights are completely different.

[77Gowing]

Yes, I am a retired electrical & mechanical engineer and I know how to calculate all permutations of ohms law for dc circuits.
More than paper pusher, I worked in the labs daily on all things elec/mechanical & electrochemical. I have the scars to prove it.
If you work with your hands, you get cuts bruises, blisters, burns etc. Mostly superficial though. Im sure you know.

Good point about wire thickness and current.
Cross sectional area of a conductor definately matters. I believe these values are publish with the awg wire gage documentation.
Good discussion. Thanks SCBOB