For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category

### DTC Descriptors

DTC P2072: Throttle Actuator Control System - Ice Blockage

### Circuit/System Description

The engine control module (ECM) controls the throttle valve by applying a varying voltage to the control circuits of the throttle actuator control (TAC) motor. The ECM monitors the duty cycle that is required to actuate the throttle valve. The ECM monitors the throttle position (TP) sensors 1 and 2 to determine the actual throttle valve position. The ECM performs diagnostics that monitor the voltage levels of both APP sensors, both TP sensors, and the throttle actuator control motor circuit. It also monitors the spring return rate of both return springs that are housed internal to the throttle body assembly. These diagnostics are performed at different times based on whether the engine is running, not running, or whether the ECM is currently in a throttle body relearn procedure. Every ignition cycle the ECM performs a quick throttle return spring test to make sure the throttle plate can return to the 7 percent rest position from the 0 percent position. This is to make sure that the throttle plate can be brought to the rest position in case of an actuator motor circuit failure

### Conditions for Running the DTC

• | The ignition is ON.

• | The speed is less than 40 km/h (25 mph).

• | The air intake temperature is greater than 40°C (104°F).

### Conditions for Setting the DTC

The actual engine speed is greater than the desired engine speed by at least 200 rpm for longer than 10 seconds or the ECM detects 3 fuel cut off's due to engine over speed while the engine is idling

### Action Taken When the DTC Sets

DTC P2072 is a type A DTC.

### Conditions for Clearing the DTC

DTC P2072 is a type A DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Throttle Actuator Control (TAC) System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Start the engine, rapidly move the accelerator pedal from the rest position, to wide open throttle position then back to the rest position. Repeat the procedure a four times. DTC P2072 should not set.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Disconnect the harness connector of the ECM. Ignition ON, load test for battery voltage on the ignition circuits at the ECM.

⇒ | If less than B+, repair the ignition circuit for an open/high resistance.

2. If all circuits/connections test OK, replace the ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification.

Engine Control Module Replacement for engine control module replacement, setup, and programming