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Discussion Starter · #1 ·
I don't leave things stock and that's all there is too it. When something bothers me, I have gotta do something about it. Well, it did and I have. Now I've got a tough one to figure out...

The OEM horn was just too wimpy for me. So I have mounted a pair of Hella "Sharp Tone" horns on my Roadmaster. One is behind the OEM horn cover and the other is just to the left of the starter motor. Both new horns have a fixed ground and the OEM horn wires operate a relay, which shunts 12+ power from the auxiliary connector under the seat to the horns. They're significantly louder than the stocker, so I want to call the operation a success.
BUT now I'm getting a DTC on the dash; "SPN 520293, FMI 5". I have the OEM shop manual and it says that that means, "Horn - Open Circuit/Short to B+", MIL "ON", and P-Code "C122A".
OK, Horn means HORN! I know what an open is and what a short is, but everything past "Horn" is meaningless to me in any useful context and the book give NO EXPLANATION WHAT SO EVER. There are PAGES of this stuff, with columns titled MIL and P-Code and NOTHING that explains what it means.
Have any of you guys got any insights on this stuff?
 

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Have any of you guys got any insights on this stuff?
Read up earlier on forum where it was replacement of headlights on a chieftain. Found by placing LED in the Halogens drew different current and he got codes. Might want to check with a tech dealing with reprograming on codes. Myself, this code stuff are computers controlling what one can do with bikes that way you are obligated to stick with manufacturer products. Good Luck on fix it
 

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I must be the only one who thinks the horn on the Springfield is loud enough. Maybe because I am used to the Honda bicycle horn, which was replaced with a 139 decibel air horn. Now the Indian horn is not as loud as that, but is loud enough to me. Good luck with your code fix and enjoy the ride. Hopefully you never have to use the horn for other than just to say hi.
 

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Do you have a schematic? Just a sketch will work. Oh, bear with me, I'm "Thinking Out Loud".

What I think is happening is, the Current flowing through the Relay Coil is not the same as the original set up, and the VCM is sensing the difference thinking it's a short circuit now. This is assuming your horn button now is powering the New relay coil and having new wiring for the horns (different path for the current to flow). So did you add an additional Relay to the circuit, or use the original OEM Relay to power both the new horns and wired in a "New Ground"?

Your new horns can have difference Resistive value than the original single horn. Also running (two coils in Parallel) lowers the resistance, thus higher current, and having (two coils in Series) increases the resistance then your Current value will be lower. How did you wire the horns (Series, Parallel)? Do you have a multi-meter to measure the coils on the horns?
 

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Discussion Starter · #5 ·
Do you have a schematic? Just a sketch will work. Oh, bear with me, I'm "Thinking Out Loud".

What I think is happening is, the Current flowing through the Relay Coil is not the same as the original set up, and the VCM is sensing the difference thinking it's a short circuit now. This is assuming your horn button now is powering the New relay coil and having new wiring for the horns (different path for the current to flow). So did you add an additional Relay to the circuit, or use the original OEM Relay to power both the new horns and wired in a "New Ground"?

Your new horns can have difference Resistive value than the original single horn. Also running (two coils in Parallel) lowers the resistance, thus higher current, and having (two coils in Series) increases the resistance then your Current value will be lower. How did you wire the horns (Series, Parallel)? Do you have a multi-meter to measure the coils on the horns?
Thanks for the input. I'll have to do a sketch of the new wiring and post it later. But, yes, the OEM horn wiring is now just powering the new relay. So the OEM system only "sees" what's happening at the relay, in place of the OEM horn. When the new relay closes, power from the auxiliary circuit sounds the 2 new horns. I wired it like that because, according to the OEM manual, there is NO RELAY in the stock system, OR it's built into the VCM. I didn't want to risk killing the VCM by having the original horn wires feed 2 horns.
It occurs to me that there are riders who've in stalled the "trumpet" style air horns on their Indians. I'm going to ask them how they wired them into the bike.
 

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Do you have a schematic? Just a sketch will work. Oh, bear with me, I'm "Thinking Out Loud"...
Could the fix be as simple as adding a proper value resistor to the OEM wires going to the relay?
 
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I don't leave things stock and that's all there is too it. When something bothers me, I have gotta do something about it. Well, it did and I have. Now I've got a tough one to figure out...

The OEM horn was just too wimpy for me. So I have mounted a pair of Hella "Sharp Tone" horns on my Roadmaster. One is behind the OEM horn cover and the other is just to the left of the starter motor. Both new horns have a fixed ground and the OEM horn wires operate a relay, which shunts 12+ power from the auxiliary connector under the seat to the horns. They're significantly louder than the stocker, so I want to call the operation a success.
BUT now I'm getting a DTC on the dash; "SPN 520293, FMI 5". I have the OEM shop manual and it says that that means, "Horn - Open Circuit/Short to B+", MIL "ON", and P-Code "C122A".
OK, Horn means HORN! I know what an open is and what a short is, but everything past "Horn" is meaningless to me in any useful context and the book give NO EXPLANATION WHAT SO EVER. There are PAGES of this stuff, with columns titled MIL and P-Code and NOTHING that explains what it means.
Have any of you guys got any insights on this stuff?
Measure the resistance of the OEM horn versus the resistance of he relay you now have in its place. All these circuits are supervised, so that circuit is sensing a change....either an open (relay is much higher resistance) or a short (relay is much lower resistance). Either way, you will have to make it the same as the OEM horn.
 

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Discussion Starter · #8 · (Edited)
Measure the resistance of the OEM horn versus the resistance of he relay you now have in its place. All these circuits are supervised, so that circuit is sensing a change....either an open (relay is much higher resistance) or a short (relay is much lower resistance). Either way, you will have to make it the same as the OEM horn.
You and V2Neal seem to both be leaning toward what I have been wondering, maybe by adding a resistor in series to the relay's coil, bringing the total resistance up to match the OEM horn is all it needs? I'm gonna have to try that.
Thanks!
 

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Series Resistor with the coil increases the resistance, thus lowering the current. Parallel resistor or a coil circuit, lowers the overall resistance, this then increases the current.
If you want to dig into more, search for "Ohm's Law". Good reading for night time sleep o_O
 

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Discussion Starter · #11 · (Edited)
Series Resistor with the coil increases the resistance, thus lowering the current. Parallel resistor or a coil circuit, lowers the overall resistance, this then increases the current.
If you want to dig into more, search for "Ohm's Law". Good reading for night time sleep o_O
I stand corrected. You and HiM caught me on that typo. I shoulda known better.
I've taken individual resistance and power-draw measurements with the OEM horn and the added Hella relay. Tomorrow I should have a set-up that fools the VCM into thinking that it's controlling the original horn.
FYI; here are the schematics. It's wired like 1b in the Hella schematic.
 

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