Need Help
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6th Gear
Joined: Mar 2019
Posts: 10
Likes: 0
From: Oxford, Alabama
Need Help
I am the proud owner of a 2003 Heritage Softail Classic, 100 year anniversary issue. My problem is I've recently discovered my tail lights and brake lights have gone out. Turn signals work. I checked the bulb, bulb was blown. After replacing it, I still don't have any lights. Checked fuses, no fuses were blown. Checked wires, to the best of my ability, and found no damage. Any help will be appreciated. I'm missing some good riding days.
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,253
Likes: 11,374
From: San Diego, CA
I am the proud owner of a 2003 Heritage Softail Classic, 100 year anniversary issue. My problem is I've recently discovered my tail lights and brake lights have gone out. Turn signals work. I checked the bulb, bulb was blown. After replacing it, I still don't have any lights. Checked fuses, no fuses were blown. Checked wires, to the best of my ability, and found no damage. Any help will be appreciated. I'm missing some good riding days.
Time to get out the voltmeter and start working from the bulb socket backwards to find out where you "lost" 12 volt power....
I noticed one quirk on my 2003 Heritage.... when I had a front turn signal bulb go out.... the opposite side, rear, turn signal flashed, until I got the bulb fixed... I have an older run/turn/brake module for my rear lights, so I suspect the quirk came from that. Once the bulb was replaced, it all worked well..
If you have a run/turn/brake module for your rear lights, or an LED bulb signal stabilizer... you may want to start your check with them....
Thread Starter
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6th Gear
Joined: Mar 2019
Posts: 10
Likes: 0
From: Oxford, Alabama
The 2003 bikes have pretty simple lights, unlike the canbus/BCM operated bikes....
Time to get out the voltmeter and start working from the bulb socket backwards to find out where you "lost" 12 volt power....
I noticed one quirk on my 2003 Heritage.... when I had a front turn signal bulb go out.... the opposite side, rear, turn signal flashed, until I got the bulb fixed... I have an older run/turn/brake module for my rear lights, so I suspect the quirk came from that. Once the bulb was replaced, it all worked well..
If you have a run/turn/brake module for your rear lights, or an LED bulb signal stabilizer... you may want to start your check with them....
Time to get out the voltmeter and start working from the bulb socket backwards to find out where you "lost" 12 volt power....
I noticed one quirk on my 2003 Heritage.... when I had a front turn signal bulb go out.... the opposite side, rear, turn signal flashed, until I got the bulb fixed... I have an older run/turn/brake module for my rear lights, so I suspect the quirk came from that. Once the bulb was replaced, it all worked well..
If you have a run/turn/brake module for your rear lights, or an LED bulb signal stabilizer... you may want to start your check with them....
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,253
Likes: 11,374
From: San Diego, CA
I noticed that when I turn the turn signals on, the right one blinks normal, but the left one blinks a little faster than normal. And when they are blinking, the rear light flashes. I haven't put a volt meter on anything yet, but I'm starting to lean towards the module being bad.
To recap, you are saying turn signals work, brake light/tail light doesn't, but when the turn signals flash, the rates are different and the tail light flashes.....???
If you have a run/turn/brake module on your bike, you never mentioned you had one, I'm betting the problem is with the module....
Easy to check. Remove the R/T/B module form the rear wiring harness. You can leave it in place for the check, just connect the OEM wires back the way they were. If the problem disappears, you know the R/T/B module has issues..... trash it and replace it with a new one...
Good luck with the fix.....
Thread Starter
|
6th Gear
Joined: Mar 2019
Posts: 10
Likes: 0
From: Oxford, Alabama
To recap, you are saying turn signals work, brake light/tail light doesn't, but when the turn signals flash, the rates are different and the tail light flashes.....???
If you have a run/turn/brake module on your bike, you never mentioned you had one, I'm betting the problem is with the module....
Easy to check. Remove the R/T/B module form the rear wiring harness. You can leave it in place for the check, just connect the OEM wires back the way they were. If the problem disappears, you know the R/T/B module has issues..... trash it and replace it with a new one...
Good luck with the fix.....
If you have a run/turn/brake module on your bike, you never mentioned you had one, I'm betting the problem is with the module....
Easy to check. Remove the R/T/B module form the rear wiring harness. You can leave it in place for the check, just connect the OEM wires back the way they were. If the problem disappears, you know the R/T/B module has issues..... trash it and replace it with a new one...
Good luck with the fix.....
Cruiser
Joined: May 2012
Posts: 158
Likes: 12
From: ontario canada
I had similar problem with my rear signal lights, I took the factory module off ,hooked front & rear togetogether ,both rear signal lights work fine now. I wonder if I need to put a new module in ?
Last edited by nanook; Apr 24, 2026 at 05:35 PM.
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Seasoned HDF Member
Joined: Sep 2008
Posts: 14,253
Likes: 11,374
From: San Diego, CA
We need more info.... Probably should start your own new thread...
Make sure to give us the year & model bike you have. Also if you added any aftermarket modules, like a run/turn/brake module, or if it's all OEM.
How the turn signals were controlled has changed over the years.
1964- They used a solid state directional flasher #68543-64C
1989- They used the turn signal canceller module #68537-89G, updated in '96 to the 68540-96
2000- They used the TSM (turn signal module) #68921-01 or TSSM (turn signal security model) #68923-00. The TSM/TSSM went through several changes until 2011
2011- With the introduction of the CanBus systems, they used a BCM (body control module) both with security #41000350G or without security #41000348G.
So you can see it's kind of important to give us the above information, as the year & model will dictate what you have on your bike...
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