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Discussion Starter #1
I need help guys! I’m running out of ideas. I tried searching other posts in this forum, Youtube, and Google - no luck. My rear right turn signal will work as a turn signal but not as a running light. I’m the 2nd owner and just bought it 2 months age (1st bike). From reading some of the other threads I know that it is not supposed to be a running light unless it was modified. The previous owner must have modified it to do so as they were working before.

Things I’ve tried already:

Replacing the turn signal relay.

Switching the right and left bulbs, then ultimately replacing both.

Checking all the wire connections under the seat.

Cleaning the turn signal switch (which had a lot of gunk in it).

Note: I’m not very handy so please be as specific as possible. Thank you!
 

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84 VT500C retro bobber
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Clean the socket? Make sure you can see two clear contact points inside the socket. Sometimes a contact will get corroded and fail.
 

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If it worked before, I'd start at the plug for that signal under the seat and check for voltage there, If you have it at the plug but not at the light, you have a broken wire in between somewhere.
 

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Note: I’m not very handy so please be as specific as possible. Thank you!

Huge thanks for being specific yourself. Quite frequently it takes 5 days, post after post, to determine the actual problem. The poster writes like we're right there in front of his bike. Thanks for using the paragraph key, too.

Anyways, the PO must have used some type of conversion module for the rear signals (below). Note: many of these converters give the rear signals a brake function too. When the brakes are applied the rear signals light up.

The module is spliced somewhere on the rear signals' wires and the module sends constant ON electricity to the rear signals on lower amps and by this means provides the rear signals with running lights. It's possible for the internal transistor for the right rear running light to go bad. At least it sound that way.

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At this point, I'm assuming that your rear signals are single filament 1156 bulbs. If instead the rear signals are dual filament 1157 bulbs, the PO did a diy version. That is, he tapped into the front signals' low-filament wire and ran a jumper to the rear signal's low-filament wire to provide the rear signals with a running light. Then the jumper or connections would be suspect.

Possibility B ..... if there isn't a R/T module (run/turn) wired on the rear signals' wires ..... AND the rear signals are single filament 1156 bulbs ..... the PO must have ran a jumper from the front signals' low-filament wire to the rear signals' single wire. This is not recommended as the high-filament in the rear signal will be constant ON. The high-filament will emit too much heat and is bad on the sockets etc. The front signals use a low-filament for running lights.
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Perhaps the rears are wired all the way forward to the feeds of the front 1157 bulbs somehow.
Maybe connected in the headlight, look for additions to the front running light wires.
I'd look for a pair of added wires running all the way forward, maybe taped to the outside of the main harness.
That's how to do it to avoid buying a module to handle it.
 

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The bulbs are 1157s. I looked for the module and don’t see it.

If rear signals are 1157 dual filaments, then it's unlikely that the PO would have used a RT module, would be redundant. RT modules are used to make rear single filament signals work like dual filament signals. In this situation, the rear signals are already dual filaments. Your bulbs are 1157 or dual filaments.

You'd have to trace the right rear signal's low-filament wire and inspect the tap or the wire itself for defects.

Generally, there are two ways to power the rear signals' low-filament so that they stay constant ON (running lights).
  • 1. Tap into the corresponding front signal's low-filament wire.
  • 2.Tap into a key ON wire.
    • A. The running light wire on the tail light (the most convenient),
    • B. Any Key ON wire X.
The low-filament wire on oem signal have a white stripe or dashes on them to distinguish them from the high-filament wire. The PO might have used aftermarket signals on the rear. If he did, the wires on the aftermarket signals still plug into the respective oem color wires.

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1999 Shadow 750 ACE VT750CD3 Modified
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I figured the wires would have to come all the way forward to be switched, so the individual running light doesn't stay on when the blinker is flashing.
That is how the fronts on my bike work anyway.
I discovered this when I tried to splice into one within the headlamp shell for my tach lighting and the turn signal killed the light.
Prior to that I thought the turn signal just visually overwhelmed the output of the running light.
 

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I figured the wires would have to come all the way forward to be switched, so the individual running light doesn't stay on when the blinker is flashing.

That's true. If the running light (low-filament) remains on, there're won't be dark moments between the blinks on the high-filament and the individual blinks will be less distinct. However, I've never noticed that much of a difference with low-filaments that never shut off. But since it can't be good on the sockets, I'd run a jumper wire to the front running lights. Ain't that much more work.

[The running lights on the front signals have their own switch which is ganged to the blinker switch. This forms a double throw double pole switch. That way when you flick the blinker it operates the running light switch in tandem. In the left pic below, both blinkers are off while both front running lights are on.

When you flick the thumblever to the right to turn on the right signals, the thumblever connects the right signals to +12. In the same motion, the thumblever disconnects the right running lights (low-filament) from +12. This turns off the low-filament in the activated signal for the duration that the activated signal is blinking. This insures that the hi and low filaments in the same bulb will never be on at the same time.

Also, the running light (low-filament) on the non-activated signal remains on and is unaffected by the thumblever moving the common +12 bridge (black L in the right graphic). In other words, while the thumblever must shut off the right running light, it must keep left running light on.

Note how the running light contacts are positioned. The right contact is on the left, while the left contact is on the right. This gives an inverse logic table. If the low filament is on, the high filament is off, and visa versa. More specifically, if the low filament is on, the high filament must be off. I think it's the most interesting switch on the entire bike. If you were to design this kind of switch it might take a few years.]

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If they wired it like I did mine, they probably spliced into a tap on the rear taillight running wire. I just replaced the socket in the stock turns with 1157 type, and spliced into the taillight running wire under the fender, instead of going all the way back under the seat. Maybe yours was done the same way?
 

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Discussion Starter #12
Well guys I appreciate all your time and help but I'm throwing in the towel on this light issue. Since the turn signals still work I'm pretty sure it's still legal to ride. I checked to see if the PO spliced the tail light wire to make it a running light, the headlight wiring to make sure no wires were crossed. I tried checking the connectors under the seat. .

Checked the turn signal relay-works. Changing and even replacing the bulbs. Checked for a module-nothing. Cleaned the turn signal switch. Bought a new rear turn signal to see if that was the issue-nothing. Made sure all the wires were properly connected just about everywhere on the bike. Checked the voltage on the wires and checked the ground wires. I feel like I've tried everything.

If by some miracle I can figure this damn thing out I will let you guys know in case anyone has the same issue.

Thanks again for your tips, advice, and diagrams.
 

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yea, the year's almost over. I persume you checked for the presence of voltage on the low-filament wire (right rear signal). Perhaps, trace the Left rear's low-filament wire. That is, since the left rear has a running light (?), its wiring scheme is sound. The low filament wire for the right rear should be its duplicate, if that makes any sense.
 

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Discussion Starter #14
yea, the year's almost over. I persume you checked for the presence of voltage on the low-filament wire (right rear signal). Perhaps, trace the Left rear's low-filament wire. That is, since the left rear has a running light (?), its wiring scheme is sound. The low filament wire for the right rear should be its duplicate, if that makes any sense.
Thanks RONW I only have a voltage tester at the moment.

Looks like I need to invest in a voltage meter.
 

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Discussion Starter #15
I finally broke down and took it to the mechanic ($100). The problem was the connector under the seat.

Thanks for all your help though!
 
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