Where to find main wiring harness / cable loom for YT Decoy MX?

[TPHmoto82]

My bike is a YT decoy mx .

where can i find a yt decoy main cables/ wire harness.

@Greg Watts

 

[Greg Watts]

Sourcing a YT Decoy harness is genuinely one of the more painful jobs in eMTB ownership right now, so let me be straight with you about where things stand.

Your Decoy MX runs the Shimano EP801 (85Nm, 600W), so the main motor wiring is Shimano's system — which is both good and bad news.

The honest state of play:
• YT-specific harnesses have been a known weak spot. @T4RZAN reported that during the YT insolvency mess, Shimano was pointing the finger at the YT harness as the fault, but no aftermarket wiring harnesses were available for the Decoy — it's a YT proprietary loom, not an off-the-shelf Shimano part → view post.
• @ziscwg confirmed YT USA is now handled through Jenson USA — they still warranty YT bikes, but you contact Jenson first and they liaise with YT → view post.

Where to actually look:
• YT direct / your regional YT service — for a UK bike, go through YT's own warranty/spares channel first. The full main harness is a YT part number, so they're the primary source.
• Jenson USA if you're Stateside — same caveat, contact them before buying.
• Shimano service centre — worth a call, because some of the connector-side bits (drive unit cables, the Z405-type light/accessory leads) are standard Shimano EP8 parts even if the full loom isn't. If only one branch of the harness is faulty, you may not need the whole thing.

Before you spend on a full harness — diagnose first:
Harness faults on these are very often corrosion at a connector, not a dead loom. @SVT_925 traced an intermittent on/off Decoy fault to corrosion in the main harness and sorted it for around $30 in parts → view post. Worth pulling each connector, checking for green crud and water ingress, and cleaning/re-seating before you write off the whole thing — eMTB harnesses are notorious for water creeping in and backdooring into connectors.

If you can tell me the exact symptom (no power, intermittent cut-outs, error code on the display, or a specific cable that's visibly damaged), I can help you work out whether it's a single cable or the full loom — and that changes the cost massively.

What's it actually doing?

 

[Folklore]

intermittent cut-outs, error code on the e-tube app

 

[Greg Watts]

intermittent cut-outs, error code on the e-tube app

Same bike, same headache, then - good to know it's not just TPHmoto82. Intermittent cutouts plus an app error code is actually a useful combo, because it narrows things down before you go spending money on a new loom.

On EP801-equipped bikes, that pairing is the classic signature of a bad connection rather than a dead motor - @Rod B. pointed out the EP800/EP801 wiring is an enclosed loop, so if any wire or connector anywhere in that loop is marginal, the whole system drops out. Vibration is often what tips a borderline connection into an actual fault, which fits "intermittent" perfectly.

Two bits of community experience worth trying before you buy a harness: • @Greeno's post - his cutouts on a Levo turned out to be the battery connection plug; a new harness fixed it, but worth checking/reseating first.

• @Astro66 found EP8 motors ridden in wet conditions throw connection errors that clear up once you clean the connector pins with contact cleaner - moisture on the internals was the culprit, not a failed part.

So before you commit to sourcing a full loom (which, as I said earlier, is a genuine pain for the Decoy): pull the battery, check the connector for corrosion or a bent pin, clean it, and reseat firmly.

What's the actual error code on the e-tube app? EP801 codes are specific enough that it'll tell us whether this is wiring, the speed sensor, or something further upstream - worth getting that before we chase a harness that might not even be the fault.

 

[Folklore]

Error 210 and one other I forgot to write down. 9 something I think.
I've replaced speed sensor, and all the ew sd300 wiring no luck. Battery works fine on other YT decoy I have, so...

 

[Greg Watts]

Error 210 and one other I forgot to write down. 9 something I think. I've replaced speed sensor, and all the ew sd300 wiring no luck. Battery works fine on other YT decoy I have, so...

Right, that's a genuinely useful elimination process you've just run - swapping in the battery from your other Decoy is the killer test here, because it rules out the one component you couldn't fix with a new loom anyway.

Straight answer on the code: I can't confirm what "Error 210" specifically decodes to on EP801 - it's not in Shimano's published list I can stand behind, and I'd rather tell you that than guess. If you can grab the exact string (E210 vs W210 matters, and the second code you half-remember starting with "9" would help a lot too), Shimano's own reference at si.shimano.com/en/error is the one to check it against, or your dealer can pull it properly via E-Tube PROJECT.

But here's what your troubleshooting has actually told us, code or no code: you've replaced the speed sensor, replaced all the EW-SD300 wiring, and proven the battery's fine by cross-testing it on a working Decoy. That's the entire "connection" theory gone - sensor, loom, battery are all cleared. Which leaves the drive unit itself.

There's a thread on here with a very similar shape to your situation - EP801 throwing a code, rider does the full cleaning/reseating/sensor-swap routine, no change, and it ended up being a warranty motor replacement from Shimano:

"Bike is generating e201 error. After powering on, the display works fine and power select button works properly. Spin the crank and the error is displayed. I've cleaned all wire ports, reseated and cleaned the main battery connection several times... Still same behavior."

That's not proof yours is the same fault, but the diagnostic pattern - everything external cleared, code persists - is exactly what points at the motor internals (torque sensor or drive unit electronics) rather than anything you can fix with a new harness. Given the EP801 is still in warranty on most Decoy MX builds, I'd push this through a dealer for a proper E-Tube PROJECT readout before spending another penny on parts - if it is the drive unit, that's a warranty claim, not a shopping trip.

 

[Folklore]

Bike shop says motor is good...
E 210 and E 914... So unsure about motor

 

[Greg Watts]

Bike shop says motor is good... E 210 and E 914... So unsure about motor

Two different codes clearing simultaneously with "motor's fine" from the shop is odd enough that I'd want more detail on what test they actually ran, @Folklore - a visual bench check and a full E-Tube PROJECT diagnostic readout are not the same thing, and only the second one properly interrogates the drive unit electronics.

Straight answer: I can't confirm what E210 and E914 specifically decode to on EP801 - neither is in a Shimano reference I can stand behind, and after your search I still can't verify them with confidence rather than guessing. Two different numeric codes firing together often means two different subsystems (sensor vs. communication/BMS-link, for instance), which would actually explain why the shop's basic motor check came back clean - they might be looking at the wrong system.

What I'd push for next: • Ask the shop for the literal E-Tube PROJECT diagnostic printout, not just a verbal "motor's good" - it'll show which subsystem each code maps to.

• Check si.shimano.com/en/error yourself against the exact strings - it's the only source I'd trust for a precise translation.

• Given you've already eliminated sensor, EW-SD300 loom, and battery, if the shop's readout genuinely clears the drive unit too, this starts looking like it could be the display/head unit or the connection between display and motor rather than the motor itself - worth asking them to check that specifically rather than re-testing what's already cleared.

Get the exact printout and I can help make sense of it properly.

 

[Folklore]

They did a diagnostic, want verbal

 

[Greg Watts]

They did a diagnostic, want verbal

That's the crux of it - "verbal" isn't a diagnostic result, it's an opinion, and you can't cross-reference an opinion against Shimano's error list. A proper E-Tube PROJECT readout gives a printout or screen capture showing exactly which subsystem each code maps to; a mechanic saying "motor's good" over the counter could mean anything from "we ran the full test" to "it span up on the bench so it's fine".

Given where you've got to - sensor replaced, EW-SD300 loom replaced, battery cross-tested clean on your other Decoy, and now E210 and E914 persisting through all of that - you're entitled to push back and ask for the actual screen output or PDF, not just their verdict. Frame it as "I need the diagnostic report for my own records/warranty file," which is a reasonable ask any shop should be able to produce in two minutes if they genuinely ran it.

If they won't or can't produce it, that itself tells you something about how thorough the check actually was.

I've said what I can stand behind on E210/E914 without the exact printout to check against si.shimano.com/en/error, and I don't want to keep guessing at codes I can't verify. You've done all the right elimination work here - if you get that printout, or if this ends up being a warranty motor swap, give me a shout and I'll help you make sense of it. Good luck with the shop.

 

[Folklore]

They did a diagnostic, want verbal

Your saying the display could be bad? It turns on and reads out and as stated wires replaced. communication or connection problem between the battery and the drive unit per Shimano...

 

[Folklore]

Your saying the display could be bad? It turns on and reads out and as stated wires replaced. communication or connection problem between the battery and the drive unit per Shimano... Plus I made a typo not want, but should have been not a verbal

 

[Folklore]

That's the codes meaning per Shimano

 

[Greg Watts]

That's the codes meaning per Shimano

Fair enough - you were right and I was wrong to write off "motor's good" as vague. If Shimano's own code definition for E210/E914 is genuinely "communication or connection problem between the battery and the drive unit," that's not an opinion, that's a specific diagnosis with a defined meaning, and I shouldn't have kept pushing back on it without seeing that. Nicely tracked down.

Here's the thing though - that diagnosis actually lands you right back where this thread started. Walk through what you've eliminated: • Speed sensor - replaced, no change

• EW-SD300 wiring - replaced, no change • Battery - cross-tested clean on your other Decoy

None of those is "the connection between battery and drive unit" in the sense Shimano means here. The EW-SD300 loom is your display/remote wiring; the battery-to-motor link is a separate, dedicated power-and-comms harness that runs down the downtube from the battery bay to the drive unit. That's the one bit of wiring you haven't swapped, and it's exactly the main loom/harness you were asking about at the top of this thread. Given sensor, battery and remote wiring are all cleared, that connector or cable run is now the prime suspect - loose pin, corrosion, or a chafed wire in that section, rather than anything inside the motor itself.

So: worth going back to that main harness, pulling it, and inspecting the connectors at both ends (battery bay and motor) for corrosion or a bent/pushed-back pin before buying a whole new loom - sometimes it's one pin, not the whole cable. If it looks clean and the fault persists, that's your part to source and replace.