Circuit Description
The intake air duct is divided into two separate runners connecting to the intake manifold tuning (IMT) valve plenum. The IMT valve plenum is an H type configuration containing the IMT valve assembly. During low speed, high load conditions the IMT valve is closed creating two separate runner paths in the incoming air ducts which aids an increasing torque. During higher engine speeds, above 3,200 RPM, the IMT valve opens creating a path between the two intake air duct runners allowing equalization of the intake air pressure which aids in increasing horsepower. The IMT valve is controlled by an IMT vacuum solenoid. Manifold vacuum is supplied to the IMT solenoid. A 12-volt supply from the manifold fuse to the IMT solenoid is applied when the ignition key is turned ON. The solenoid is normally closed which will not allow vacuum to pass through it. When the engine speed and load are increased above a calibrated threshold, the engine control module (ECM) provides a ground to the solenoid, energizing the solenoid and allowing vacuum to be applied to the IMT valve. When the IMT solenoid is commanded OFF, the voltage of the control circuit is high, battery voltage. When the IMT solenoid is commanded ON, the voltage of the control circuit is low, near 0 volts. The ECM applies a pull up voltage of 2.6-4.6 volts on the control circuit to differentiate between an open, a short to ground, or a short to voltage. If the ECM detects a voltage above a predetermined threshold, DTC P0662 will set.
Conditions for Running the DTC
| • | The engine speed is more than 40 RPM. |
| • | The battery voltage is more than 8.05 volts and less than 18 volts. |
| • | The ECM must change the state of the IMT solenoid from OPEN to CLOSED. |
Conditions for Setting the DTC
The voltage of the control circuit is above a predetermined threshold.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | 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 non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Listen for an audible click when the intake manifold tuning (IMT) solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.
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This step verifies that the engine control module (ECM) is providing a ground to the IMT solenoid.
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This step tests for an open in the battery positive voltage circuit to the IMT solenoid.
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This step tests if voltage is constantly being applied to the IMT solenoid control circuit.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
Does the IMT solenoid click with each command? | Go to Step 3 | Go to Step 4 | |
3 |
Does the DTC fail this ignition? | Go to Step 4 | Go to Intermittent Conditions |
Does the test lamp turn ON and OFF? | Go to Step 5 | Go to Step 6 | |
Does the test lamp turn ON and OFF when commanded with a scan tool? | Go to Step 9 | Go to Step 11 | |
Does the test lamp remain OFF with each command? | Go to Step 8 | Go to Step 7 | |
7 | Test the control circuit of the IMT solenoid for a short to ground or an open. Did you find and correct the condition? | Go to Step 14 | Go to Step 10 |
8 | Test the control circuit of the IMT solenoid for a short to voltage. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
9 | Inspect for poor connections at the IMT solenoid. Did you find and correct the condition? | Go to Step 14 | Go to Step 12 |
10 | Inspect for poor connections at the harness connector of the engine control module (ECM). Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
11 | Repair the battery positive voltage circuit of the IMT solenoid. Did you complete the repair? | Go to Step 14 | -- |
12 | Replace the IMT solenoid. Did you complete the replacement? | Go to Step 14 | -- |
13 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | Go to Step 14 | -- |
14 |
Does the DTC run and pass? | Go to Step 15 | Go to Step 2 |
15 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |
