Everything You Need to Know. VanMoof SX3 Harness Loom
What is the Harness Loom?
The harness loom is a cable bundle that connects your bike’s electronics — motor, lights, brakes, sensors, and onboard computer. It runs internally through the bike frame. If it’s faulty, you’ll see a range of electrical failures.
Common Symptoms of a Faulty Harness Loom
Here’s what to watch for:
1. Intermittent Power or Display Dropouts
- Bike shuts off randomly or resets.
- Display goes dark without battery dying.
- Error codes that vanish after a restart.
2. Non-Responsive Kick Lock
- Kick lock won’t engage or disengage.
- App says it’s locked, but the wheel is free — or vice versa.
3. Front/Rear Light Issues
- Lights flicker, don’t turn on, or behave inconsistently.
4. Motor Cuts Out While Riding
- Boost button stops working.
- Bike suddenly rides like a regular, non-electric bike.
5. Inconsistent Light or Sound Level
- Sound features or front/back light are responding weirdly.
6. Multiple Error Codes (1-21, 44, 45, 48, etc.)
- Errors related to communication between control modules.
Step-by-Step Diagnostic Guide
Step 1: Check Firmware & App
- Update the VanMoof app.
- Ensure bike firmware is current.
- If issues persist after updates, move on.
Step 2: Inspect Cable Damage
- Gently move handlebars side to side — see if power or lights cut off.
- Perform reboots with different positions of handlebars.
Step 3: Run a Soft Reset
- Hold power button 10+ seconds to force restart.
- If the problem returns consistently, it's likely not a software glitch.
Step 4: Observe Patterns
- Is the issue temperature sensitive (heat or cold)?
- Does rain or moisture worsen the symptoms?
When to Suspect the Harness Loom Specifically
If you’re seeing multiple symptoms from different systems (motor + lights + lock), and they come and go, it’s almost always a loom issue. The internal cables may be pinched, frayed, or suffering from a poor factory connection.
Pro Tip for Technicians
Use a continuity tester or multimeter on both ends of the loom (if bike is disassembled) to test if any wires are broken internally.
Final Advice
If you suspect a harness loom issue:
- Document symptoms with video/screenshots.
- Avoid riding if motor cutouts are sudden — it’s a safety risk.
Solution: Harness Loom Replacement
Before you start.
Please watch the X3 S3 Wiring Harness replacement video to assess the scope of work required:
For New Wiring Loom Installation:
Always take these extra steps before installation for optimal performance:
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Remove all plastic zip ties to ensure the cables are free and flexible.
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Remove the sleeve from the motor cable to free up all the internal cores.
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Apply a high-quality electrostatic lubricant across all cables, but be cautious to avoid getting lubricant into the sockets.
These precautions will help ensure a smoother and more reliable setup.
How to unscrew Wiring Loom main screws
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Use good quality tools
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If there is a 'screw stripped issue' - how to deal?
https://www.instructables.com/5-Ways-to-Remove-a-Stripped-Screw/
Remove all sharp cable transitions
Polish sharp edges inside the fork:
Restrict fork ability to turn far left and far right
Two extra screws can be added to the existing central screw:
What else can be helpful?
- A bike stand
- 3D printed tool to hold a battery socket: can be downloaded here
- Specialised tools to reroute the cables:
Other photos
