Zumo XT Wiring on NX500 – Power Down Behavior

[Ron_WI]

Hello Friends,

I sold my '07 ST1300 back in January and bought a Honda NX500. I had my ST from new, and it served me well over all those years and miles. Now at 77, my enthusiasm for cross-country road trips has waned, and I wanted something lighter for local rides. The NX500 has been a great choice so far, especially with a few mods (Sargent seat and Givi touring windscreen).

I’m hoping to get some electrical advice on wiring my Garmin Zumo XT to the NX500. On the ST1300, I powered it by grounding to the battery negative post and posi-tapping into the ACC circuit for switched power. It worked perfectly.

This time, I decided to use an APIELE 4-pin relay (12V 40A) with a 30A fuse, which I replaced with a 3A fuse since the Zumo only draws 1.5–2A. I couldn't find an ACC wire to conveniently tap into and would be using the taillight power wire. I thought a relay would be a better way to go in that case. Here’s how I wired it:

• Relay Pin 30: Battery + terminal
• Relay Pin 87: Zumo XT power input wire (red)
• Relay Pin 86: Taillight power wire via posi-tap (12V trigger)
• Relay Pin 85: Ground (battery - terminal)
• Zumo ground wire (black): Battery - terminal

Everything works, but I’m noticing something odd when I power down. On the ST, when I turned off the key, the Zumo would show a screen saying it lost power, and then it would shut down after 10–15 seconds. On the NX500, when I turn the key off, it shows the same screen—but it stays lit for a minute to a minute and a half before going black. Then, when I turn the key back on, the Zumo comes on almost instantly, rather than booting up from a cold start. This makes me think it’s going into sleep mode, drawing a small amount of power instead of fully shutting off.

I measured the voltage at the Zumo mount pins with a multimeter. When the bike’s been off for several minutes, I get 0 volts at the pins. When I power the bike on, I get 5.25V at the pins. When I turn the bike off, voltage drops from 5.25V down to about 3.6V quickly, then slowly declines to 0V over 2–3 minutes.

Is this normal behavior for the Zumo XT, or is something in my wiring causing it not to fully power down? Any insights or suggestions would be greatly appreciated!

 

[Al st1100]

check voltage at relay pins key, the only thing
I can think of is to make sure the colored wires at the relay match the pin numbers and they were not pushed into the wrong slot. That's a simple relay system, you have it wired correctly.

 

[Ron_WI]

OK, I can double-check those relay pins in the morning. Before installing the posi-tap, I checked the taillight connector near where I placed the tap and found 12+ volts with the key on and 0 volts with the key off, just as it should be.

What seems odd is the slow voltage drop at the Garmin mount pins when I turn the key off. It doesn’t drop to 0 volts immediately; instead, it takes nearly two minutes to fall from 5.25 volts (when powered on) back to 0. It’s more like slowly turning a rheostat down rather than the on/off switch behavior I expected. I never had a reason to check that voltage on my ST, so I’m wondering if that’s normal—or if it’s what’s causing the Zumo XT not to power down the way it did on my ST.

 

[MidLife]

OK, I can double-check those relay pins in the morning. Before installing the posi-tap, I checked the taillight connector near where I placed the tap and found 12+ volts with the key on and 0 volts with the key off, just as it should be.

What seems odd is the slow voltage drop at the Garmin mount pins when I turn the key off. It doesn’t drop to 0 volts immediately; instead, it takes nearly two minutes to fall from 5.25 volts (when powered on) back to 0. It’s more like slowly turning a rheostat down rather than the on/off switch behavior I expected. I never had a reason to check that voltage on my ST, so I’m wondering if that’s normal—or if it’s what’s causing the Zumo XT not to power down the way it did on my ST.

I know it is not the answer to your question, but doesn't the NX have an accessory plug like the 500X does, that you could use to power the GPS up and down? Eastern Beaver sells a splitter if you need one.

CB500X Aux Power Splitter

Honda CB500X auxiliary power splitter. Use when you need to connect extra devices. Fits the auxiliary power outlet under the seat.

www.easternbeaver.com

How to hardwire a XT2 to Honda CB500X so it auto powers on and off.

This will hopefully be of benefit to those who own a Honda CB500X, (mine is a 2020 model) and want to know how to connect the Zumo XT2 to the Honda and have…

zumouserforums.co.uk

 

[Ron_WI]

The CB500X has a handy accessory plug under the seat, but my NX500 doesn’t have one there. It has a 2-wire accessory connector under the left fairing that the dealer used for the 12V ACC socket that I use with a cigarette lighter USB socket for my phone. There’s also a 3-wire accessory connector under the right-side fairing that’s intended for heated grips, and has a wire going to the instrument panel. I wasn’t sure if that would affect anything in the instruments if I installed my GPS there. So I decided to wire it using a relay, which seemed more straightforward.

 

[Ron_WI]

This has been interesting!

Request:

I’d like to ask if anyone with a multimeter and a Zumo XT wired into a switched circuit on their bike could check something for me. When your bike is on, you should see around 5.25 volts on the two small pins in the Zumo XT mount. When you turn the bike off, you should see that voltage drop to 0 volts (or very close to it).

On my setup, when I turn the bike off, the voltage at those pins doesn’t drop to 0 volts immediately—it decays slowly over a few minutes instead of shutting off quickly. I’m trying to figure out whether this is normal behavior or if there’s an issue with my wiring or mount.

Reasoning:

I checked pin 86 of my relay, which I tapped into the taillight positive wire using a posi-tap. Key off, it’s at 0 volts; key on, it’s at 12+ volts; and when I turn the key off, it drops to 0 volts immediately. Good, that’s normal.

Then I measured the voltage at the pin on the relay supplying power to the Zumo XT. When the key is turned off, it shows the same slow drop in voltage as the mount pins. But when I disconnected the wire going to the Zumo XT and tested the relay pin again, it dropped to 0 volts immediately. That suggests the relay itself is working properly and the slow voltage drop is coming from the Zumo XT side.

The wiring going to the Zumo XT mount has a small black box in the line, which is apparently a DC-DC converter to step down the bike’s 12+ volts to the 5 volts that the Zumo XT uses. ChatGPT suggested that the mount’s internal converter (and possibly a capacitor bank) might be backfeeding a small residual voltage into the circuit after the key is turned off, causing the slow decay over 2+ minutes.

I reached out to Garmin support via chat, but the person I spoke with wasn’t able to go deep on this technical issue. They referred me to the installation instructions, which simply call for connecting the power cable directly to the battery—no switched power. I asked for more technical help, and they sent me a link to the power cable specs, which didn’t help either.

ChatGPT suggested adding a bleed resistor across the Zumo XT’s power input to discharge that voltage faster (within a few seconds), which would force the unit to shut down completely rather than lingering in power-saving mode. But before I try that, I’d like to confirm whether this slow voltage drop at the mount is normal for this GPS model.

Thanks in advance for any help you can provide!

 

[MidLife]

.......when I turn the key back on, the Zumo comes on almost instantly, rather than booting up from a cold start. This makes me think it’s going into sleep mode,.....

Browsing around, looks like it can happen.

Garmin's answer to it (according to AI):

Troubleshooting:

1. Ensure Correct Power Connection: Make sure the zūmo XT is plugged directly into the motorcycle with the original Garmin power cable. Avoid using splitters, USB cables, or third-party cables.

Looks like they much prefer your ST set up.

 

[Ron_WI]

Yes, I think you may be right. I hate to give up, but I may have to rethink this project. Maybe I should try wiring it through the 3-wire Options connector that's intended for heated grips, as I won't be installing those.

 

[Willsmotorcycle]

I’m thinking it’s a feature not a bug, mine says, and I’m paraphrasing here, “hey you lost external power, did you mean to? Take corrective action “. If I take no action in 20 secs or so, it shuts off saving data before shutdown.

Is there a downside to this happening on your bike?

 

[MidLife]

Yes, I think you may be right. I hate to give up, but I may have to rethink this project. Maybe I should try wiring it through the 3-wire Options connector that's intended for heated grips, as I won't be installing those.

Or give a shot at the 2-wire Connector on the left side with a Splitter....although Garmin advises against Splitters.

 

[Josh_ST]

I have an XT on my ST1300 cabled into the Quartet Harness. I can check my mount to see if I have the decay of power. I expect not, as it powers down relatively quickly (20-30 seconds?)

 

[Ron_WI]

I have an XT on my ST1300 cabled into the Quartet Harness. I can check my mount to see if I have the decay of power. I expect not, as it powers down relatively quickly (20-30 seconds?)

I'd appreciate that Josh. I'm curious to know what you see in your configuration.

I'll try adding a bleed resistor across the Zumo XT’s power input to discharge that voltage faster and see if that helps. That would be the easiest thing to try.

 

[ST1100Y]

When I turn the bike off, voltage drops from 5.25V down to about 3.6V quickly, then slowly declines to 0V over 2–3 minutes.

When in idle (no consumer connected) that 12/5V converter will take some time to discharge... explains the ramping down you'd measured...

That power supply is rated [IN 10-30V/1.5A OUT 5V/1.5A], marginal numbers the ACC circuit/Quartet Harness can handle with easy... your relay seems a bit over-designed

IIRC has that XT two power down modes: hibernate and fully OFF...
the later requires holding the ON/OFF button for longer period and confirm the screen prompt...
but when the AUX power is turned off it should display a screen prompt, [stay on] or [power down] selectable?

 

[Josh_ST]

I'm seeing a decay of about 30 seconds to get below half a volt. Here's a video:

 

[Ron_WI]

I'm seeing a decay of about 30 seconds to get below half a volt. Here's a video:

That’s really interesting, Josh — thanks for sharing the video! It looks very similar to what I’m seeing. When I mentioned mine was taking 2–3 minutes to power down, I meant it was taking that long to drop all the way down to 0 volts. I’ll double-check to see how long it takes to get to around 0.5 volts, because your video looks pretty much like what I’m experiencing.

When you turn the key off on your bike, does your Zumo power down completely, or does it go into power-saving mode? I’ve noticed that if it’s completely off, it takes about 20 seconds or so to boot back up when I turn the bike back on. But in power-saving mode, it comes back on almost instantly.

 

[Josh_ST]

It's been off the mount and in the fairing pocket since I did the test (15+ hours). I'll get out there and see how it "powers up" later this morning.

 

[Nashcat]

This post got my curiosity up, so I went to the garage and checked my XT2 on the ST13. Mine is wired through a fuse block, powered by a relay, so I’m positive (pun) the power turns off with the key.

It takes mine about 30 seconds to drop to 0.0 VDC after turning off the key. The shutdown procedure on the screen may be related to the amount of charge of the internal battery in the XT2 when powered down.

John

 

[Josh_ST]

2~3 second boot up: