Taillight wire as trigger for switched power

On my '15 RTW, I decided to use the taillight power wire (grey with red stripe) as the trigger wire for my PDM60 power distribution module, per the advice/experience of others here. Before wiring to it, I decided to make sure I had the right wire, and found some interesting behavior, at least with the taillight connector unplugged.

With the ignition off, voltage at the connector is zero. At ignition on, the voltage goes immediately to 12.5 V or so. But at ignition off, it drops to 5.5 V and stays there for about a minute and half, after which it drops to zero. Well, this was interesting. My guess was that there's a CANbus chip in the taillight that does a shutdown handshake with the central controller, and that 5.5 V is to power the chip until it completes the handshake or, in this case, times out.

After tapping into the wire anyway, I confirmed this. Measuring with the connector plugged into the taillight, the voltage drops to zero almost immediately upon turning the ignition off.

If it comes up again, you can positap the hot wire that goes to the accessory plug by the rear seat. I know this wires stays hot for a minute or two after turning the ignition off as it runs my compressor, but the compressor is only a 6amp compressor so not sure what happens w/ voltage drop.

I also use the rear power plug wire to trigger my system. It stays on about a minute afer the ignition is shut off.

Yeah, I was looking for one that shut off immediately, and I was aware of the delay on the power plug.

CANbus does some weird stuff.

On my '15 RTW, I decided to use the taillight power wire (grey with red stripe) as the trigger wire for my PDM60 power distribution module, per the advice/experience of others here. Before wiring to it, I decided to make sure I had the right wire, and found some interesting behavior, at least with the taillight connector unplugged.

 

With the ignition off, voltage at the connector is zero. At ignition on, the voltage goes immediately to 12.5 V or so. But at ignition off, it drops to 5.5 V and stays there for about a minute and half, after which it drops to zero. Well, this was interesting. My guess was that there's a CANbus chip in the taillight that does a shutdown handshake with the central controller, and that 5.5 V is to power the chip until it completes the handshake or, in this case, times out.

 

After tapping into the wire anyway, I confirmed this. Measuring with the connector plugged into the taillight, the voltage drops to zero almost immediately upon turning the ignition off.

As you have probably already discovered, this gray/red tail light wire will not delay shutting down your PDM60 when you turn the bike off. Even though 5 volts will exist for 60 seconds on this wire it will still shut down the PDM60 right away with no delay.

On my K1600 I had used a wire which powered the light in the top box and this wire remained energized for about a minute after powering the bike off. At first it was not a big deal. Overtime I wished I had a connection which allowed the power for the PDM60 to turn off when I turned off the bike. When wiring up the RTW I really wanted the accessory power to turn off with the bike and that gray/red tail light wire does just that even though it has some voltage to it for a minute.

Another option is the red/green wire for the passenger power socket.

On my '15 RTW, I decided to use the taillight power wire (grey with red stripe) as the trigger wire for my PDM60 power distribution module, per the advice/experience of others here. Before wiring to it, I decided to make sure I had the right wire, and found some interesting behavior, at least with the taillight connector unplugged.

 

With the ignition off, voltage at the connector is zero. At ignition on, the voltage goes immediately to 12.5 V or so. But at ignition off, it drops to 5.5 V and stays there for about a minute and half, after which it drops to zero. Well, this was interesting. My guess was that there's a CANbus chip in the taillight that does a shutdown handshake with the central controller, and that 5.5 V is to power the chip until it completes the handshake or, in this case, times out.

 

After tapping into the wire anyway, I confirmed this. Measuring with the connector plugged into the taillight, the voltage drops to zero almost immediately upon turning the ignition off.

 

As you have probably already discovered, this gray/red tail light wire will not delay shutting down your PDM60 when you turn the bike off. Even though 5 volts will exist for 60 seconds on this wire it will still shut down the PDM60 right away with no delay.

Just to clarify, if the connector is plugged into the taillight, the voltage on that wire drops to zero almost immediately upon power off. It's only when the taillight connector is NOT plugged in to the taillight (or if something's not working) that the voltage stays at 5.5 volts for 90 seconds.

On my K1600 I had used a wire which powered the light in the top box and this wire remained energized for about a minute after powering the bike off. At first it was not a big deal. Overtime I wished I had a connection which allowed the power for the PDM60 to turn off when I turned off the bike. When wiring up the RTW I really wanted the accessory power to turn off with the bike and that gray/red tail light wire does just that even though it has some voltage to it for a minute.

 

Another option is the red/green wire for the passenger power socket.

That one always stays on for a while after ignition off.