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 sensors 1 and 2 to determine the actual throttle valve position.

The ECM detects the throttle blade is stuck open or stuck closed for 1 s.

DTC P2072 is a Type A DTC.

DTC P2072 is a Type A DTC.

Inspect for a condition in which the throttle valve may have been held open. For example, ice may have formed in the throttle bore causing the throttle valve not to close.

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Description and Operation

Throttle Actuator Control (TAC) System Description.

1. Ignition ON, observe the DTC information with a scan tool. DTCs P0121, P0122, P0123, P0221, P0222, or P0223 should not set.

⇒	If any DTCs are set, refer to DTC P0068, P0121, or P0221 , or DTC P0122, P0123, P0222, or P0223.

2. Verify throttle position sensor 1 voltage is between 0.4-0.9 v, and throttle position sensor 2 voltage is between 4.1-4.7 .

⇒	If not within the specified range, refer to DTC P0068, P0121, or P0221 , or DTC P0122, P0123, P0222, or P0223for further diagnosis.

3. Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times. DTC P2072 should not set.

⇒	If DTCs P0121, P0122, P0123, P0221, P0222, or P0223 set while performing this procedure, refer to DTC P0068, P0121, or P0221, or DTC P0122, P0123, P0222, or P0223.

4. Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times. DTC P2072 should not set.

⇒	If DTCs P0121, P0122, P0123, P0221, P0222, or P0223 set while performing this procedure, refer to DTC P0068, P0121, or P0221 , or DTC P0122, P0123, P0222, or P0223.

5. 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.

1. Inspect the Q38 Throttle Body for the following conditions:

•	A throttle blade that is not in the rest position

•	A throttle blade that is not in the rest position

•	A throttle valve that opens or closes without spring pressure

⇒	If a condition is found, replace the Q38 Throttle Body.

Note: Disconnecting the Q38 Throttle Body harness connector causes additional DTCs to set.

2. Ignition OFF, disconnect the harness connector at the Q38 Throttle Body.
3. Install fused jumper wires between the Q38 Throttle Body and harness connector of the following circuits:

•	Low reference circuit terminal 6

•	5-volt reference circuit terminal 2

•	Throttle position sensor 1 circuit terminal 1 or throttle position sensor 2 signal circuit terminal 4

4. Ignition ON, test for less than 0.5 V on the motor control circuit terminal 3 and motor control circuit terminal 5.

⇒	If greater than the specified range, test the appropriate motor control circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

Note: The scan tool TAC motor command is disabled, if multiple TP sensor or TAC circuit DTCs are set.

5. Ignition OFF, command the TAC Motor with the scan tool, while measuring the voltage of the TAC motor control circuit terminal 3 and TAC motor control circuit terminal 2.

⇒	If the voltage changes between 0.0  V to greater than 10.5 V on both circuits, replace the Q38 Throttle Body.

⇒	If the voltage changes between 0.0 V to less than 10.5 V on either circuit, test for an open or a short to ground in the appropriate TAC motor control circuit.

⇒	If the circuits test normal, replace the K20 Engine Control Module (ECM).

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.