C0310 – Motor A/B Circuit Open

System: Chassis | Standard: ISO/SAE Controlled | Fault type: Circuit/Open

Official meaning: Motor A/B Circuit Open

Definition source: SAE J2012 naming/structure guidance

What Does C0310 Mean?

C0310 – Motor A/B Circuit Open means the chassis control system has detected an open circuit condition in the Motor A/B electrical circuit. The official meaning is: Motor A/B Circuit Open.

An “open” indicates the control module cannot see the complete electrical path it expects in the Motor A/B circuit. When continuity is lost (for example, a disconnected connector, a broken wire, or an internal open in the motor circuit), the module may not be able to operate the motor and may disable the associated chassis function to prevent unintended behavior.

C0310 is an ISO/SAE controlled diagnostic trouble code in the Chassis system, and the enforced fault type is Circuit/Open.

Quick Reference

• Code: C0310
• Official Title: C0310 – Motor A/B Circuit Open
• Official Meaning: Motor A/B Circuit Open
• System: Chassis
• Standard classification: ISO/SAE Controlled
• Fault type: Circuit/Open
• What it indicates: Loss of electrical continuity in the Motor A/B circuit (no valid electrical path/response)
• First checks: Connector seating, terminal condition, harness damage, power feed and ground integrity to the motor circuit

Symptoms

When C0310 is present, symptoms typically relate to a chassis function that relies on the Motor A/B circuit. The exact function depends on the vehicle’s design and how Motor A/B is implemented, but an open circuit generally leads to a non-operational motor or a disabled feature.

• Warning indicator illuminated: a chassis-related warning lamp or system indicator may turn on
• Function disabled or limited: the system that uses the motor may be reduced, unavailable, or placed into a protective mode
• Intermittent operation: if the open is intermittent, operation may cut in and out with vibration, harness movement, or temperature changes
• No motor response when commanded: the motor may not run when the system requests operation
• Additional stored chassis DTCs: other related circuit or performance codes may be present depending on what the module monitors

Common Causes

C0310 is set when the control module detects an open circuit condition affecting Motor A/B. Causes generally fall into wiring/connection faults, power/ground delivery faults, or an internal open in the motor circuit.

• Open in Motor A/B wiring: broken wire, damaged harness, or internal conductor break that creates loss of continuity
• Connector not fully seated: partially latched connector at the motor, module, or an intermediate junction
• Terminal problems: backed-out terminal, spread terminal, corrosion, moisture intrusion, or overheating that prevents electrical contact
• Open power feed to the motor circuit: blown fuse, open in the power supply wiring, or a fault in the circuit that provides power to the motor path
• Open ground path: broken ground wire, poor ground point connection, or excessive resistance that behaves like an open
• Internal open in the motor circuit: an open winding or internal connection that results in no continuity through the motor circuit
• Open in a control module driver path: an internal open in the output stage that prevents completing the circuit (evaluate only after external circuit checks)
• Poor prior circuit repair: incorrect terminal crimp, poor splice, or damaged pin fitment creating an open condition

Diagnosis Steps

Diagnosing C0310 requires confirming the fault is truly an open circuit and locating where continuity is lost in the Motor A/B circuit. Use a scan tool capable of reading chassis codes, a digital multimeter, and the correct wiring diagram for the specific vehicle configuration.

1. Confirm the code and status: scan for C0310 and any additional chassis DTCs. Record freeze-frame/failure record data and note whether the code is current or history.
2. Verify the symptom: check for warning indicators and confirm the affected chassis function is inoperative or limited. If the system supports it, attempt a functional command (active test) to reproduce the issue.
3. Identify the Motor A/B circuit path: use service information and wiring diagrams to determine the motor circuit routing, connector locations, and power/ground sources. “Motor A/B” must be verified by the vehicle documentation.
4. Perform a visual inspection: inspect harness routing from the control module to the motor/actuator. Look for chafing, pinched sections, heat damage, or areas where movement could stress the wiring.
5. Inspect connectors and terminals: check the motor connector and module connector for bent pins, backed-out terminals, corrosion, moisture, or incomplete locking. Correct connector seating issues before deeper testing.
6. Check power supply to the circuit: with the circuit configured as specified in service procedures, verify the motor circuit receives the required power feed. If the system can be commanded on, confirm voltage is present when commanded and does not drop out.
7. Check ground integrity: verify the ground path using a voltage drop test under load (preferred when possible). An open or high-resistance ground can cause the module to interpret the circuit as open.
8. Test continuity of Motor A/B wiring: with power off and connectors disconnected as required, measure continuity end-to-end on the Motor A/B circuit conductors. Wiggle the harness and connectors during testing to identify intermittent opens.
9. Check for high resistance that behaves like an open: inspect suspect terminals, splice points, and junctions. If continuity exists but readings are unstable or resistance is excessive, address the connection fault.
10. Test the motor circuit for an internal open: measure resistance/continuity of the motor circuit at the specified terminals and compare with service specifications. An internal open should be concluded only after confirming the external wiring, power, and ground are intact.
11. Evaluate module output only after external checks: if the circuit, power, ground, and motor circuit test within specification, follow service procedures to verify the module’s ability to drive/monitor the circuit.
12. Clear codes and recheck: after repairs, clear DTCs and perform a functional verification under conditions that previously set the code. Confirm C0310 does not return.

Possible Fixes

Repairs for C0310 focus on restoring continuity and correct electrical operation in the Motor A/B circuit.

• Repair open wiring: repair or replace damaged wiring/sections in the Motor A/B circuit and secure routing to prevent repeat damage
• Restore connector/terminal integrity: clean corrosion, correct terminal fitment, repair water intrusion, and ensure connectors are fully seated and locked
• Restore power feed: repair opens in the power supply wiring and replace related protection components only after identifying the cause of the open condition
• Restore ground path: repair open ground wiring and service the ground connection point to ensure a solid electrical connection
• Replace the motor/actuator if internally open: only after confirming the motor circuit itself has an internal open and the external circuit is good
• Address control module driver issues if verified: only after confirming proper power/ground, verified circuit integrity, and failed output testing per service procedures

Can I Still Drive With C0310?

Driving with C0310 depends on which chassis function relies on the Motor A/B circuit and how the vehicle responds to the fault. Because the code indicates a circuit open, the motor may not operate and the related chassis function may be disabled or limited.

If a warning indicator is on and a stability- or traction-related chassis function is reduced, vehicle control characteristics may be affected under low-traction conditions. If you experience reduced system operation, drive conservatively, avoid demanding conditions where the affected chassis function is needed, and have the open circuit diagnosed and repaired as soon as practical.

Repair Costs

Repair cost depends on whether the confirmed root cause is wiring, connector condition, a switch or module issue, or the labor needed to diagnose the fault correctly.

Last updated: March 26, 2026