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Motorcycle Repair/front right turn signal not flashing

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QUESTION: i have a wiring question.  i read your profile and hope you can help. 1976 cb550f right turn signal not working. all other lights function.

I took off right side turn signal to inspect it. While it was dangling with the key to the on position the housing brushed against the front fork and it turned on.  I held it to fork and it blinked off and on.

I then decided to unplug the left side turn signal and plug the wires into the right side harness inputs.  turned on and it blinked. i guess this means the wiring harness side is working because it made the left turn signal flash.

Kinda lead me to think there is a bad ground in the housing?  Or bad ground on the bulb?

ANSWER: Russell, generally turn signal issues are due to either bad bulbs, loose wiring connections or more commonly a bad ground.

Because the light began to flash when grounded against the fork, the problem is a bad ground to the housing. There is a ground lead for the bulb socket which could be loose/failed. The socket is rubber mounted, so the bulb needs that connection to complete the circuit. The housing is bolted direct to the headlight system, which is supported by the fork ears, but those are rubber mounted too, so good clean ground connections must be maintained for the blinkers to work.

Take the turn signal apart and inspect the socket and wiring for good clean connections. All that humidity in Hawaii can cause lots of wiring issues due to corrosion damage.

The front turn signals have running lights and the blinker function, so a double filament bulb must be used and all three wires properly connected.

Bill Silver

---------- FOLLOW-UP ----------

QUESTION: Hi Bill

something was wrong with the socket I just replaced it all is well.

Had a question about starting bike.  I have a no start no crank issue.  Push start button, solenoid gives one click that's it.  Jumped solenoid starter spun.

Any idea where I can start trouble shooting?

Thanks

ANSWER: Glad you got your signals working again, Russell.

Go to: http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php#class  for wiring diagrams.

Unfortunately, your bike gets lumped in with most of the 4 cylinder street machines of that era which have auto-on headlights. The original factory switches tended to die and require replacement with updated versions.

If the headlight/starter functions seem intermittent, so that the headlight sometimes doesn't come on and the starter works and vice-versa, then it is likely the starter button switch on the handlebars, which is about a $100-125 item. If the button seems firm when pressed and the headlights come on consistently, then it could be the solenoid. Some of the older solenoids can be partially disassembled and cleaned. You need to check the solenoid by putting power on the black lead and grounding the yellow/red lead. Using a test light might be sufficient to test out the wiring on the bike leading to the solenoid.

There is a starter safety switch on the clutch lever side, with a plunger that extends when you pull the clutch in. If the plunger is broken or stuck that might also be an additional factor. There is also a rectifier in the circuit to prevent a reverse current situation.

You mention jumping the solenoid, but at the two battery posts or at the primary windings leads? Jumping across the posts tells you that you have sufficient battery power, but bypasses the solenoid's internal functions.

In most cases of intermittent starter button function, when you have a fully charged battery and good solenoid, is that the starter button function is dying.

Bill Silver

---------- FOLLOW-UP ----------

QUESTION: Hey Bill,

I jumped the solenoids posts and got starter to spin.  i thinking that tells me that starter and solenoid are fine, but something i stopping it from firing.  Correct?

Also my headlight is off the bike because i was working on a grounded ignition switch wire.  does the headlight have to be on to complete the circuit?

Answer
Russell, when you jumped the big posts, you bypassed the normal function of the solenoid. The solenoid works by energizing the wire coils inside to create a magnetic field, which pulls a plunger up against the bases of the two big posts to close the circuit. If the plunger is sticking or the power to the primary windings isn't sufficient, then the solenoid function fails.

The handlebar starter switch is a dual function switch....

When the ignition switch is turned ON, power goes to a set of contacts in the handlebar switch which turns the headlight ON automatically. When you depress the starter button, the starter switch circuit is engaged, energizing the starter solenoid AND breaking the closed headlight circuit, which turns the headlight OFF while the starter motor is engaging, to lessen the current draw on the battery during start-up. So, you see, these are two separate electrical circuits being operated by the single starter button function. Button OUT - Headlights... Button pressed IN ... starter circuit engaged and headlight is OFF.
FYI
Also when the dimmer switch is on LO, the running lights up front will be illuminated. When you switch to HI beams, the running lights turn OFF.

Bill Silver

Motorcycle Repair

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Bill Silver

Expertise

Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.

Experience

I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

Organizations
VJMC (Vintage Japanese Motorcycle Club) of North America

Publications
VJMC newsletter, as editor for two years and as contributing editor currently.

Education/Credentials
3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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