P2071
DTC P2071
DTC DESCRIPTOR
DTC P2070
Intake Manifold Tuning (IMT) Valve Stuck Open
DTC P2071
Intake Manifold Tuning (IMT) Valve Stuck Closed
DIAGNOSTIC FAULT INFORMATION
IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection
TYPICAL SCAN TOOL DATA
CIRCUIT/SYSTEM DESCRIPTION
An intake manifold tuning (IMT) valve is used to change the intake manifold plenum configuration. When the IMT valve is open, the intake manifold is configured to one large plenum. When the IMT valve is closed, the intake manifold is configured to 2 smaller plenums. The IMT valve improves engine performance at low and high engine speeds depending on the engine load. The IMT valve assembly consists of the following:
- A tuning valve
- A microprocessor
- An electric motor
- A hall-effect sensor
- An ignition voltage circuit
- A ground circuit
- A variable tuning signal circuit
- An IMT fan position signal circuit
Ignition Voltage Circuit
An ignition voltage is supplied directly to the IMT valve assembly from the powertrain relay through a 10-amp fuse. The ignition voltage provides power to a microprocessor and to a motor that rotates the IMT valve within the intake manifold.
Ground Circuit
Ground circuit is supplied directly to the IMT valve assembly. This circuit provides ground for the micro-processor and the motor.
Variable Tuning Signal Circuit
During operation when the valve is open the control module applies ground to the variable tuning signal circuit which indicates to the microprocessor within the IMT valve to position the valve to the closed position which turns the motor ON and rotates the IMT valve within the intake manifold plenum.
IMT Fan Position Signal Circuit
When the IMT valve is rotated the hall-effect sensor is reporting the position of the valve to the ECM. The control module uses this feedback signal to determine the position of the IMT valve.
The control module compares the commanded state of the variable tuning signal circuit and compares it to the IMT Fan Position Signal Circuit for being stuck open, stuck closed.
CONDITIONS FOR RUNNING THE DTC FOR P2070
- The engine speed is between 1,000-3,600 RPM.
- The system voltage is between 9-18 volts.
- DTCs P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0220, P0222, P0223, P0660, P1258, P1516, P2071, P2077, P2078 P2101, P2119 P2135, P2138, or P2176 are not set.
CONDITIONS FOR SETTING THE DTC
P2070
The control module detects that the IMT valve is stuck open. This diagnostic runs continuous when the above conditions are met.
P2071
The control module detects that the IMT valve is stuck closed. This diagnostic runs continuous when the above conditions are met.
ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
- The control module commands the TAC system to operate in the Reduced Engine Power mode.
- A message center or an indicator displays Reduced Engine Power.
- Under certain conditions the control module commands the engine OFF.
CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.
CIRCUIT/SYSTEM VERIFICATION
Command the IMT valve ON. The IMT Valve Command parameter should transition from open to closed and the IMT Valve Feedback parameter should transition from 20-22 percent to 77-80 percent.
CIRCUIT/SYSTEM TESTING
1. Monitor the scan tool for any other DTCs.
- If DTC P0660 is set, diagnose that DTC first. Refer to DTC P0660. P0660
2. Ignition ON, disconnect the IMT valve harness connector and measure for 0.5 volt on the variable tuning signal circuit and ground.
- If less than 0.5 volt test the variable tuning signal circuit for a short to ground, or a faulty control module.
3. Measure for 5.0 volts on the IMT fan position signal circuit at the IMT valve harness connector.
- If more than 5 volts, test the IMT fan position signal circuit for a short to voltage.
4. Disconnect the ECM harness connector for the IMT fan position signal circuit and measure the resistance of the circuit.
- If more than 5 ohms, repair the high resistance condition.
- If all circuits test OK, replace the IMT valve.
REPAIR INSTRUCTIONS
- Control Module References
- Intake Manifold Tuning Valve Replacement
REPAIR VERIFICATION
IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests