What Does C0308 Mean?
C0308 indicates the control module (typically ABS/ESC or active suspension) has detected an abnormally low voltage or resistance in Motor A or Motor B circuit. This usually affects active chassis systems such as ABS pump motors, active suspension damper motors, or electronic brake force distribution actuators. The 'low' designation means the circuit voltage is below the expected threshold, suggesting a short to ground, internal motor failure, or wiring fault.
Common Causes
35%
Short to ground in motor control circuit wiring harness or connector corrosion causing low resistance path
30%
Failed motor windings with internal short or degraded insulation in the actuator motor
20%
Faulty control module driver circuit output transistor or internal short
15%
Damaged or chafed wiring causing intermittent short to chassis ground
Diagnostic Steps
1
Step 1: Perform visual inspection of motor harness connectors and wiring for damage, corrosion, water intrusion, or chafing against chassis components. Check connector pin terminals for bent pins or corrosion.
2
Step 2: Disconnect the motor connector and measure resistance between motor terminals using a digital multimeter. Compare readings to manufacturer specifications (typically 2-10 ohms for most chassis motors). Also check for continuity to ground on each motor terminal (should be infinite resistance/open circuit).
3
Step 3: With motor disconnected, measure voltage at the control module side of the harness connector while commanding motor activation through scan tool bidirectional controls. Verify control module is attempting to supply proper voltage (typically 12V pulsed or variable).
4
Step 4: If wiring and voltage supply are correct but motor shows low resistance or continuity to ground, replace the motor assembly. If motor tests good but circuit still shows low, inspect for harness damage between motor and module, checking for pinched wires near mounting points.
5
Step 5: After repairs, clear codes, perform motor relearn/calibration procedure if required, and test drive vehicle while monitoring live data for proper motor operation and absence of code return.
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
C0308 indicates the control module (typically ABS/ESC or active suspension) has detected an abnormally low voltage or resistance in Motor A or Motor B circuit. This usually affects active chassis systems such as ABS pump motors, active suspension damper motors, or electronic brake force distribution...
The most common cause of C0308 (Motor A/B Circuit Low) is: Short to ground in motor control circuit wiring harness or connector corrosion causing low resistance path
Typical repair costs for C0308 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may be safe for limited driving, but ABS, traction control, stability control, or active suspension functions may be disabled or operating in fail-safe mode. Braking performance could be reduced in emergency situations, so immediate repair is recommended and aggressive driving should be avoided.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C0308 to identify the root cause.
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Quick Info
Category
Chassis
System
Chassis Control System (ABS/ESC/Active Suspension)
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
