P1589 Throttle Control Unit Modulated Command Malfunction

• P1589: Throttle Control Unit Modulated Command Malfunction – This code indicates a malfunction in the throttle control unit’s ability to modulate commands properly. It typically relates to issues with the electronic throttle control system.
• P0120: Throttle/Pedal Position Sensor/Switch “A” Circuit – This code is triggered when there is an issue with the circuit of the throttle position sensor or pedal position switch.
• P0220: Throttle/Pedal Position Sensor/Switch “B” Circuit – Indicates a problem with the circuit related to the second throttle position sensor or pedal position switch.
• P2135: Throttle/Pedal Position Sensor/Switch “A”/”B” Voltage Correlation – This code is set when there is a discrepancy between the voltage readings of two throttle/pedal position sensors/switches.
• P2101: Throttle Actuator Control Motor Circuit Range/Performance – Indicates that there is an issue with the performance or range of the throttle actuator control motor circuit.

p1589 – Throttle Control Unit Modulated Command Malfunction

Typical Severity: Critical

Common Causes

P1589 Throttle Control Unit Modulated Command Malfunction

Common causes:

• Faulty throttle control unit
• Wiring or connector issues in the throttle control system
• Electronic throttle body malfunction
• Engine control module (ECM) software issue

 

Common Misdiagnosis

OBD2 Code: P1589

Description: Throttle Control Unit Modulated Command Malfunction

Common Misdiagnosis: Replacing the throttle body without verifying the integrity of the wiring or connectors.

 

Common Diagnostic Steps

OBD2 Code: P1589

Description: Throttle Control Unit Modulated Command Malfunction

• Check for any other related trouble codes that may be present and address them first.
• Inspect the throttle body and throttle position sensor for signs of damage or wear.
• Ensure all electrical connections to the throttle control unit are secure and free from corrosion.
• Test the wiring harness between the throttle control unit and the engine control module (ECM) for continuity and shorts.
• Use a scan tool to monitor live data from the throttle position sensor to ensure it is operating within specifications.
• Perform a throttle body cleaning if carbon buildup is observed, which can affect performance.
• If applicable, perform a relearn procedure for the throttle position sensor using an appropriate scan tool.
• If issues persist, consider replacing the throttle control unit or associated components as necessary.