Modified on Wed, 5 Nov at 9:40 AM

How to Replace MOD Controller

In this article: You’ll replace the controller on your MOD BIKE to restore or upgrade your bike’s performance.

This Article Applies to the Following Bikes

Difficulty

★★☆ Medium

Estimated Time

20–30 Min

Before You Start

Tools you will need

• Adjustable Wrench (included in your bike tool kit)
• Multitool with Allen Wrenches (included in your bike tool kit)
• Bolt Tray (or any small container for screws)
• Cable snippers or scissors
• Zip ties (3–5 new ones)

Preparation

• Make sure the bike is powered off and standing securely on the kickstand.

• Work in a well-lit area with space around the rear tank section.

• Remove any accessories that block access to the tank.

Steps | MOD Easy

If you do not have a MOD Easy, click here for instructions for all other bikes.

Step 1: Remove the Battery

1. Use your key to open the battery tank.

2. Once open, use the battery key to unlock the battery from its housing.

3. Carefully pull the battery forward to release it from the battery housing, then place it safely aside.

Step 2: Disconnect Main Battery Housing

1. Use a 3mm Allen wrench to remove the screws securing the main battery housing.

2. Take off the black plastic cover to expose the controller compartment.

3. Unplug the main battery cables from the controller. Set the battery housing and plastic cover aside for reinstallation later.

Step 3: Free the Cables 

• Use snippers to carefully cut the three zip ties securing the controller cables — take care not to cut any wires.

Step 4: Disconnect the Old Controller

• Disconnect the motor cable’s julet connector — do not twist to avoid bending the pins.

• Disconnect the remaining cables from the controller.

Step 5: Remove the Old Controller

1. Pull the cable with the red tip out of the controller compartment and down through the seat tube cable channel.

2. Pull the cable with the small black tip out of the controller compartment and down the same channel. 

Note: These cables must be pulled down first and out of the way — otherwise, the motor cable will not fit through the seat tube channel

3. Pull the motor cable upward, threading its wide Julet connector through the seat tube channel. Set the old controller aside.

Step 6: Thread the New Controller’s Cables

1. Take the new controller and gently feed the motor cable down through the seat tube cable channel.

2. Feed the small black cable up through the seat tube channel and into the controller compartment.

3. Feed the red cable up through the seat tube channel and into the controller compartment.

Note: Follow this exact order — if done differently, the cables may not fit through the seat tube channel properly.

Step 7: Reconnect All Cables

1. Connect red to red, aligning pins and arrows, then press firmly.

2. Connect large black to large black, align pins and arrows, and push firmly.

3. Connect small black to small black, align pins and arrows, press until secure.

4. Leave the square black connector disconnected. 

5. Route motor cable neatly along the frame, following its original path. Connect it. Align arrows, and push straight — do not twist.

6. Connect large yellow to large yellow. Connect small yellow to small yellow. Align pins, and push firmly.

7. Tuck cables and new controller neatly into the compartment and confirm all are secure.

Step 8: Reinstall the Cover and Battery Housing

1. Reinstall the black plastic cover over the controller compartment.

2. Use a 3 mm Allen wrench to tighten the four screws securing the main battery housing.

3. Before fully tightening, push the battery housing as far back as possible to ensure proper battery fit. Tighten screws fully.

Step 9: Secure the Cables and Reinstall the Battery

1. Use three new zip ties to secure the cables to the frame. On the chainstay, thread the zip ties through the two built-in guide rings to hold the cable firmly in place.

2. Trim the excess ends of the zip ties.

3. Reinstall the battery by sliding it backward into its housing until fully seated.

4. Close the battery tank — listen for a click to confirm it’s securely locked.

Steps | All Bikes

Step 1: Remove the Battery

1. Turn the battery off by switching it to the “O” position.

2. Once off, use the battery key to unlock the battery from its housing.

3. Carefully remove the battery by pulling it upward from the frame, then place it safely aside.

Step 2: Uncover the Controller and Free the Cables

1. Locate the controller housing beneath the crankset area of the frame.

2. Using a 3 mm Allen wrench or multi-tool, remove the bolts securing the controller cover.

3. Use snippers to carefully cut the zip ties securing the controller cables — take care not to cut any wires.

4. Cut any remaining zip ties along the frame to fully free the controller wiring harness.

Step 3: Disconnect the Old Controller

1. Disconnect the motor cable’s julet connector — do not twist to avoid bending the pins.
2. Gently slide the controller out of its compartment.
3. Disconnect the remaining cables from the controller.

Step 4: Remove the Old Controller

1. Pull the cable with the red tip out of the controller compartment.
2. Remove the round rubber gasket from the compartment opening — this will make space for the thicker motor cable. 
3. Gently pull the motor cable out, threading its wide julet connector through the rubber gasket opening.
4. Feed the cable through the compartment hole and set the old controller aside.

Note: If the gasket isn’t removed, the motor cable julet connector will not fit through the hole.

Step 5: Thread the New Controller’s Cable

1. Take the new controller and position it near the compartment opening.
2. Gently feed the motor cable through the compartment opening and rubber gasket.
3. Reinstall the round rubber gasket securely into the compartment opening.
4. Pull the cable with the red tip back into the controller compartment.

Step 6: Reconnect All Cables

1. Connect red to red, aligning pins and arrows, then press firmly.
2. Connect large black to large black, align pins and arrows, and push firmly.
3. Connect small black to small black, align pins and arrows, press until secure.
4. Connect yellow to yellow, align pins, and push firmly.
5. Leave the small yellow and square black connectors disconnected. Do not connect these.
6. Connect the motor cable, align arrows, and push straight — do not twist.
7. Tuck cables and new controller neatly into the compartment and confirm all are secure.

Step 7: Secure the Cables and Reinstall the Cover

1. Route all cables neatly along the frame, following their original path.
2. Use three new zip ties to secure the cables to the frame.
3. Trim the excess ends of the zip ties.
4. Reinstall the controller cover beneath the crankset area, and tighten the bolts with a 3 mm Allen wrench or multi-tool.

Step 8: Reinstall the Battery

1. Carefully slide the battery back into the frame housing until it’s fully seated.

2. Use the battery key to lock the battery in place.

3. Turn the battery on by switching it to the “I” position.

Troubleshooting

• The bike won’t power on after installation → Ensure the battery is locked in place and switched to “I”. Recheck all controller connections, especially the red, black, and yellow cables.
• Display turns on but motor doesn’t respond → Verify that the motor cable arrows are aligned and the connector is fully seated. Never twist the plug, as this can bend the pins.
• Intermittent power loss while riding → Inspect all cable connections and zip ties. Make sure no cables are pinched or bent under the cover or inside the frame.
• Error code or flashing display → A connector may not be fully seated or may be mismatched. Unplug and reconnect each Julet connector, matching by color and size.
• The battery won’t charge or fit properly → The housing may not be positioned correctly. Loosen the bolts, push the housing fully backward, then retighten.
• Lights or pedal assist not working → Confirm the small black (rear light) and yellow (pedal assist) connectors are fully seated and aligned with matching arrows.
• The controller feels warm during first rides → Mild warmth is normal. If it becomes hot to the touch or performance drops, stop using the bike and contact MOD Support.

⚠️ Note: Always double-check all battery connections before riding. Loose cables or improper installation may result in power loss or damage. If unsure, visit a certified MOD BIKES service location.

FAQs

• Do I need to disconnect the battery before replacing the controller?
  Yes. Always turn the battery to the “O” position and remove it before doing any electrical work.
• Can I ride if one of the connectors isn’t plugged in?
  No. All connectors must be properly seated and aligned for safe operation.
• How do I know if the controller is working after installation?
  Turn the battery to “I” and power on the display. If the screen lights up and the motor engages when pedaling or using the throttle, it’s functioning correctly.
• The motor cable won’t fit through the seat tube — what should I do?
  Ensure the red and small black cables are pulled down first. The motor cable must be threaded last for proper clearance.

Warning

⚠️ Important Safety & Liability Notice

These instructions are provided as a general guide for MOD BIKES products. Always ensure that all screws, bolts, and fasteners are properly tightened and secured before riding. Improper assembly or maintenance may result in damage, injury, or voiding of warranty.

If you are not confident performing these steps, please seek assistance from a qualified MOD BIKES technician or authorized service provider. MOD BIKES shall not be held liable for injury, damage, or loss caused by improper use, assembly, or failure to follow these guidelines. Local laws and regulations may apply.