Circuit Description
The intake manifold upper plenum is divided into two separate runners, one for each bank, by an intake manifold runner control (IMRC) valve. During low speed, high load conditions the IMRC valve is closed creating a longer runner path inside the plenum which increases torque. During higher engine speeds, above 3,200 RPM, the IMRC valve opens creating a shorter runner path inside the plenum which increases horsepower. The IMRC valve is controlled by an IMRC vacuum solenoid. Manifold vacuum is supplied to the IMRC solenoid. A 12-volt supply from the manifold fuse to the IMRC 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 a vacuum to be applied to the IMRC valve. When the IMRC solenoid is commanded OFF, the voltage of the control circuit is high, battery voltage. When the IMRC solenoid is commanded ON, the voltage of the control circuit is low, near zero 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.
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 IMRC solenoid from OPEN to CLOSED. |
Conditions for Setting the DTC
The voltage of the control circuit drops below 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 runner control (IMRC) solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.
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Tests for voltage at the coil side of the IMRC solenoid. The manifold fuse supplies power to the coil side of the IMRC solenoid.
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Verifies that the ECM is providing ground to the IMRC solenoid.
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Tests if ground is constantly being applied to the IMRC solenoid.
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 IMRC 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 ON? | Go to Step 5 | Go to Step 11 | |
Does the test lamp turn ON and OFF? | Go to Step 9 | Go to Step 6 | |
Does the test lamp remain ON with each command? | Go to Step 8 | Go to Step 7 | |
7 | Test the control circuit of the IMRC solenoid for an open or high resistance. Did you find and correct the condition? | Go to Step 14 | Go to Step 10 |
8 | Test the control circuit of the IMRC solenoid for a short to ground. Did you find and correct the condition? | Go to Step 14 | Go to Step 10 |
9 | Inspect for poor connections at the IMRC 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 voltage circuit of the IMRC solenoid. Did you complete the repair? | Go to Step 14 | -- |
12 | Replace the IMRC solenoid. Refer to Intake Plenum Switchover Solenoid Replacement . 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 | |
