P1589 – Throttle Control Unit Modulated Command Malfunction

P1589 Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P1589 Possible Causes

Faulty Throttle Control Unit,Throttle Control Unit harness is open or shorted,Throttle Control Unit circuit poor electrical connection

P1589 Description

The Powertrain Control Module (PCM) tests the electronic throttle for the ability of the throttle plate to return to the default (limp home) position from both the open and closed positions.