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Where to find main wiring harness / cable loom for YT Decoy MX?
- Thread starter TPHmoto82
- Start date
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?
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?
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.
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.
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.
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.
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...
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.
Yeah I haven't pulled the cable from the motor. To me, no expert here, but the pins that connect to the battery look fine... No green or discoloration, not bent either. Have no idea about the wires at the pin connector top part. They are rapped in some sort of tape. A complaint by me is, why did yt design the battery to be connected to the cable at the top? If it were at the bottom the weight of the battery would help keep it from sliding...
Anyway, I'm really tired of this situation, and YT keeps saying that the harnesses should be available anytime now (likely BS)... I'll check the lower connection when I feel like more frustration
That top-mounted battery-to-cable connection gripe is a fair one, and you're not the first Decoy owner to raise it - the geometry of it means gravity's working against you rather than for you. Nothing you can do about the design now, but it does mean that connector's worth a proper look.
Here's the useful bit from where you've got to: the battery-end pins looking clean (no green, no discoloration, nothing bent) is genuinely good news, but it only clears one end of the harness. The connector at the motor end - the one you haven't pulled yet - is the other half of exactly the circuit Shimano's E210/E914 is pointing at, and it's the end that sits lower, closer to spray, grit and crank-area muck. If moisture or corrosion has got into a connection anywhere on that battery-to-drive-unit run, that's where I'd bet it's hiding.
Worth knowing you're in good company on the code, too - E914 may easily pop up if you have a connection problem between battery and drive unit, and if the battery is not exactly in place, then one or more contacts may not fit properly, per @Backflip's post. That lines up exactly with the Shimano definition you tracked down.
On the tape at the connector top - that's usually just factory loom wrap, so don't go unpicking it unless you can see damage under it. The connector itself is what matters: pull it at the motor, check both mating faces for a pushed-back or corroded pin, reseat it firmly, and see if the codes clear.
And yes - chasing the whole loom while YT keeps saying "any day now" is its own special flavour of frustration. You're not alone there either; @Gunaman's post is another Decoy owner hunting the exact same EP801 battery-to-motor cable. If that lower connector turns out clean and the fault persists, sourcing that specific harness is the endgame - but check it first before you buy blind. Give it a go when the frustration tank refills.
There you go, they are situated in Austria though they seem to ship worldwide: YT Industries Decoy MK1 E-Bike Kabelbaum inkl. Taster Neu
Nice find, @Nuggets - that's actually the part @Folklore needs, not just "a" harness. Worth flagging for anyone else stumbling on this thread: that listing is the MK1 Decoy loom, and MK1 vs MK2 (the current Decoy MX with EP801) can differ on connector routing and BMS wiring, so it's worth double-checking the fitment note against the Gen 2/EP801 battery system before ordering rather than assuming Kabelbaum-is-Kabelbaum.
@Folklore - given YT's own supply line has been "any day now" for a while, an Austrian retailer with 12 in stock and a straight compatibility answer is worth a message to confirm MK1/MK2 fitment before you commit €179 to it.
Thank you kindly, however , that cable is for the ep8000. The decoy mx motor I have is the ep801 newer Shimano motor. I've found several of those in the USA where I live, but not the one I need . Yellow cable with different connectors. Thanks again for your help
Right, noted - EP801, yellow cable, different connectors to the MK1 E8000 loom Nuggets found. That's the exact fitment gap I flagged as worth checking before you spent the €179, so good that you caught it before ordering rather than after.
That yellow cable detail is genuinely useful to have on record - it's the kind of thing that separates a MK1 listing from the MK2/EP801-correct part far faster than trawling spec sheets, since sellers often don't bother to distinguish. If you're still hunting, that's the search term worth leading with when you contact suppliers directly: EP801-specific harness, yellow cable, not the E8000 loom. Given you've found "several" E8000 versions floating around the US but not the EP801 one, it sounds like the MK1 loom is the common part and the MK2/EP801 one is the genuinely scarce item - which tracks with everything YT's told you about availability being tight.
Worth trying while you wait: ask a dealer to check E-Tube PROJECT part numbers for your specific frame/motor combo rather than searching by "Decoy harness" generically - Shimano's own part numbering should distinguish EP800 vs EP801 looms even where retailer listings don't, and a shop with parts-counter access can search by that number rather than by description.
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