The
C51 code on a Suzuki Burgman 650 indicates an issue with the
CVT (Continuously Variable Transmission) motor circuit, specifically that the CVT motor is not receiving the correct operating voltage from the CVT control unit. This can result in symptoms like the bike being stuck in one gear (often first), failure to shift in automatic or manual mode, or the FI (Fault Indicator) light illuminating. Here’s a breakdown of the issue, potential causes, and steps to troubleshoot based on available information:
###
What the C51 Code Means
- Bike stuck in a single gear (e.g., first gear, limiting speed to ~20-50 mph).
- Inability to shift in automatic or manual mode.
- FI light (F1) on the dashboard, sometimes accompanied by an ABS light.
- CVT motor may not spin, or gears may not engage properly.
https://www.burgmanusa.com/threads/fault-code-f1-with-c51.157641/https://www.burgmanusa.com/threads/my-650-just-threw-a-c51-error.166325/http://www.scootergt.net/showthread.php?12767-Code-panne-C51=
###
Potential Causes
1.
CVT Motor Issues:
- Faulty or seized CVT motor.
- Motor may work when tested with 12V directly but fail under load or in the system.
http://www.scootergt.net/showthread.php?12767-Code-panne-C51=
2.
Wiring or Connection Problems:
- Loose, corroded, or damaged wiring/coupler connections between the CVT motor and the ECM (Engine Control Module) or CVT controller.
- Poor connection at the ECM plug or CVT motor connector.
https://www.burgmanusa.com/threads/my-650-just-threw-a-c51-error.166325/https://www.burgmanusa.com/threads/burgman-650-2007-c51-error.165658/https://www.burgmanusa.com/threads/abs-light-then-f1-c51-code-2009-an650.174796/
3.
Pulley Position Sensor (PPS):
- A malfunctioning PPS can cause a false C51 code, as the controller expects feedback from the PPS to confirm motor movement. A bad PPS is typically associated with a C52 code, but it can sometimes trigger a C51.
https://burgmanusa.com/forums/15-burgman-650-2002-thru-2012/52148-f-i-light-code-c-5-1-a.htmlhttps://www.burgmanusa.com/threads/f1-error-code-help-needed.51950/page-2
4.
CVT Mechanical Issues:
- Seized or stripped gears in the CVT, such as the plastic gear the motor meshes with.
- Debris (e.g., feed corn from rodents, metal particles, or other foreign substances) inside the CVT housing, causing binding or blockages.
https://www.burgmanusa.com/threads/fault-code-f1-with-c51.157641/https://www.burgmanusa.com/threads/burgman-650-2007-c51-error.165658/https://www.burgmanusa.com/threads/code-c58-on-my-cluster.41864/
- Primary pulley stop bolt or other internal CVT component failure (e.g., primary bearing collapse or broken gears).
https://www.burgmanusa.com/threads/fault-code-f1-with-c51.157641/https://www.burgmanusa.com/threads/fi-light-and-wont-shift-out-of-1st-gear-code-c51.169957/
5.
CVT Controller/ECM Issues:
- Faulty CVT control unit or ECM not sending the correct voltage to the motor.
- For 2002-2004 models, separate controllers for the CVT and engine could cause communication issues, potentially triggering C51 (or C50).
https://www.burgmanusa.com/threads/codes.146722/?sortby=oldesthttps://www.burgmanusa.com/threads/code-c58-on-my-cluster.41864/
6.
Other Factors:
- Center stand switch issues may prevent upshifting but typically do not trigger a C51 code.
https://www.burgmanusa.com/threads/burgman-650-2007-c51-error.165658/https://www.burgmanusa.com/threads/fi-light-and-wont-shift-out-of-1st-gear-code-c51.169957/https://www.burgmanusa.com/threads/f1-error-code-help-needed.51950/page-2
- Low oil in the middle chamber or other unrelated issues (e.g., ABS faults) might coincide but are unlikely to directly cause C51.
https://www.burgmanusa.com/threads/abs-light-then-f1-c51-code-2009-an650.174796/
###
Troubleshooting Steps
1.
Check Wiring and Connections:
- Inspect the CVT motor connector for loose or corroded pins. It’s located near the lower left part of the CVT assembly.
https://www.burgmanusa.com/threads/my-650-just-threw-a-c51-error.166325/
- Check the ECM plug (located between the headlights on the Burgman 650) for secure connections and clean any corrosion.
https://www.burgmanusa.com/threads/abs-light-then-f1-c51-code-2009-an650.174796/
- Test continuity and voltage at the CVT motor coupler:
- Disconnect the center stand switch.
- Start the bike on the center stand in auto mode, raise engine speed, and check if voltage changes at the coupler.
- Test continuity from red and black wires to ground (should read infinity) and resistance through the motor wires (should be <0.8 ohms).
https://www.burgmanusa.com/threads/burgman-650-2007-c51-error.165658/
2.
Test the CVT Motor:
- Remove the CVT motor and test it by applying 12V directly. If it spins freely, the motor is likely functional, but test it under load if possible.
http://www.scootergt.net/showthread.php?12767-Code-panne-C51=https://www.burgmanusa.com/threads/burgman-650-2007-c51-error.165658/
- If the motor doesn’t spin when installed and powered by the ECM, suspect wiring or controller issues.
https://www.burgmanusa.com/threads/f1-error-code-help-needed.51950/page-2
3.
Inspect the PPS:
- Test the pulley position sensor per the service manual. A faulty PPS may not trigger a C52 code but can cause C51. Replacement cost is ~$160-$209.
https://burgmanusa.com/forums/15-burgman-650-2002-thru-2012/52148-f-i-light-code-c-5-1-a.html
4.
Examine the CVT Assembly:
- Remove the rubber drain nipple at the bottom of the CVT and inspect for debris (e.g., rodent feed, metal particles). Use a scope or light to check inside.
https://www.burgmanusa.com/threads/fault-code-f1-with-c51.157641/
- Check if the plastic gear meshed with the CVT motor has excessive play or is seized. If it won’t turn, internal CVT components (e.g., gears, primary pulley, or stop bolt) may be damaged.
https://www.burgmanusa.com/threads/fault-code-f1-with-c51.157641/https://www.burgmanusa.com/threads/f1-error-code-help-needed.51950/page-2
- If comfortable, open the CVT to inspect for broken parts, worn belts, or other issues. This requires mechanical expertise and may be best left to a professional.
https://www.burgmanusa.com/threads/fault-code-f1-with-c51.157641/
5. **Check the CVT Controller/E