OOPS Title should read - Back Left Turn signal Out, Front LEFT Turn Signal Fast Blink, Everything on the RIGHT is normal.

Hi All,
I'm looking for help resolving an issue with my turn signals. I'm going to throw a lot out there so as to cover issues I've read in other threads here.

My bike is clean and well kept 07 FLHTC. Its electrical system is unmodified all original equipment - no LEDs or other aftermarket stuff, just factory incandescent.

I was riding Road Guard in a group with my emergency flashers (all four signals) on all day. They were working just fine for most of the day. On the last leg of the ride, someone told me my back left signal was out.

Since then, I bought a $150 new flasher modulator, not change.
Bought new $27 PC board for back fender where wiring harness breaks out to all the tail lights.
Bought new exact replacement incandescent bulbs from Harley and installed all 4 new for only $8. Also checked contact quality and cleaned all of them even tough there was no dirt present.

Tested the PC Board breakout pins with the following results:
Back right turn signal (working) ground and voltage present with signal enabled
Back left turn signal (non-working) ground present, no positive voltage present with signal enabled
Front right turn signal light works as it should.
Front left turn signal bulb starts blinking normally and on about the 4th blink, begins to blink rapidly.
Front left signal light's original bulb was functional but black inside (new bulb acts the same as the old).

I removed the battery power for about 10 minutes after changing all the signal bulbs and tried again. Still no back left signal.
I removed the seat and examined all visible wires and fitting. No pins are missing, discolored or bent. No cables look damaged.

At this point, I'm not sure what else to do...

Any ideas?

Thanks in advance,
Miles

 

What kind of bike?
Black is the ground.
Are they the little bullet style light, they are notorious for loosing their ground.
Check at the bulb for voltage in both prongs, bulb out. Be careful to not touch the base of the socket while checking this.
Check for ground at the base of the bulb with it in the socket.

 

2007 FLHTC Electra Glide Classic

Full sized original factory signal lamps, not bullet style.

Yes, black is ground and present in all turn signals. Voltage is not present at back left. If I remember correctly, it's the purple wire that's dead.

I wish it was ground... Easy to fix.

Thanks for asking.

 

Misread, thought you said black, not back:-)
There should be a connector at the front of the rear fender check that wire there, clean the contacts and put some dielelectric grease in it.

 

All good there. I actually also replaced that breakout board per the Harley ship's suggestion. The old board was clean and tidy and still filled with clear blue goo. I bought a new board and replaced all connections. All wires and pins are clean and secure.

I'm thinking that it's a problem more upstream. I also changed out the signal modulator, per the dealer. The new one didn't solve the problem either. Again, all pins and wires were clean and in good condition.

Maybe in the front fairing?

 

Un plug that connector at the front of the fender see if you are getting 12 v flashing on the #3 socket, the violot wire.

 

Good call! I checked and the purple wire has power before the coupler at the front of the back fender. The connectors and ends look good. It looked good and clean but I applied contact cleaner on that portion of the connector and cleaned it with cotton tips. I still get 0.00 at the back.
Do you think it's cut under the fender?
I'll take the trunk and fender off tomorrow after work and see what I find.

 

Its flashing 12 at the connector? Then we know we have the right wire.
Yea it is pretty common for wires to get damaged under the fender.
Try doing a continuity check on that wire, it will be terminal 5 in the rear.

 

Sure enough no continuity. I think I'll stop by the dealer and pickup a replacement harness. I don't want to just repair it. I want to replace it and be done.

 

The fast blinking light is what happens when a incandescent bulb goes out. The system does this to notify the rider that a bulb is out. It is commonly referred to as Hyper-Flashing. No need to troubleshoot that since it is working as intended.