Actuator Supply Voltage "B" Circuit High
P2671 indicates the Engine Control Module (ECM) has detected abnormally high voltage in the Actuator Supply Voltage B circuit. This circuit supplies power to various engine actuators, and the excessive voltage can damage sensitive electronic components if not corrected promptly.
What You Might Notice
- Check Engine Light (MIL) illuminated
- Engine may run rough or stall
- Loss of power or reduced performance
- Transmission shift issues or limp mode
- Multiple related actuator fault codes
Most Common Causes
- 1
Charging system fault
A faulty alternator or voltage regulator overcharging the system, causing voltage to exceed normal operating range (typically above 14.5V).
- 2
Wiring or connector damage
Water intrusion, corrosion, melted connectors, or damaged wiring in the actuator supply circuit causing abnormal voltage readings.
- 3
Short to power in circuit
An unintended connection between the actuator supply line and a high-voltage source, forcing voltage above normal levels.
- 4
Defective ECM or power distribution module
Internal failure of the ECM or integrated power distribution module preventing proper voltage regulation.
How to Diagnose It
- 1
Check Charging system fault — A faulty alternator or voltage regulator overcharging the system, causing voltage to exceed normal operating range (typically above 14.5V).
- 2
Check Wiring or connector damage — Water intrusion, corrosion, melted connectors, or damaged wiring in the actuator supply circuit causing abnormal voltage readings.
- 3
Check Short to power in circuit — An unintended connection between the actuator supply line and a high-voltage source, forcing voltage above normal levels.
- 4
Check Defective ECM or power distribution module — Internal failure of the ECM or integrated power distribution module preventing proper voltage regulation.
How to Fix It
- 1
Test and replace alternator if faulty
Use a multimeter to test charging voltage at idle and under load. Voltage should be 13.5-14.5V. If higher, the alternator or voltage regulator is defective and requires replacement.
- 2
Inspect and repair wiring and connectors
Visually inspect all wiring and connectors in the actuator supply circuit for corrosion, water damage, melting, or loose connections. Repair or replace damaged components as needed.
- 3
Check battery condition and connections
Verify the battery voltage is correct (12.6V at rest) and inspect all battery cables and terminals for corrosion or loose connections. Replace battery if voltage is incorrect.
- 4
Test and replace ECM or power module
If wiring, charging system, and battery check out normal, the ECM or power distribution module may be internally faulty. This requires professional diagnostics and potential replacement.
Need a deeper diagnosis?
Search for related repair guides or browse by system.