Circuit Description
Ignition voltage is supplied directly to the AIR vacuum control solenoid. The powertrain control module (PCM) controls the solenoid by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component on, the voltage of the control circuit should be near 0 volts. When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be near battery voltage. If the fault detection circuit senses a voltage other than what is expected, this DTC will set.
The PCM will monitor the control circuit for the following:
| • | A short to ground |
| • | A short to voltage |
| • | An open circuit |
| • | An open solenoid |
| • | An internally shorted or excessively low resistance solenoid |
When the PCM detects any of the above malfunctions, this DTC will set and the affected driver will be disabled.
Conditions for Running the DTC
| • | The ignition voltage is between 9-18 volts. |
| • | The engine speed is more than 80 RPM. |
| • | The PCM driver transitions from ON to OFF or from OFF to ON. |
Conditions for Setting the DTC
| • | A short to ground, an open circuit, or a short to battery voltage is detected on the control circuit. |
| • | The condition is present for at least 30 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns the malfunction indicator lamp (MIL) off after 3 consecutive drive trips that the diagnostic runs and does not fail. |
| • | A current DTC clears when the diagnostic runs and does not fail. |
| • | A History DTC clears after 40 consecutive warm-up cycles if this or any other emission related diagnostic does not report any failures. |
| • | Use a scan tool in order to clear the MIL/DTC. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. |
Diagnostic Aids
Notice: Do not insert test equipment probes (DVOM etc.) into any connector or fuse block terminal. The diameter of the test probes will deform most terminals. A deformed terminal will cause a poor connection, which will result in a system failure. Always use the J-35616 GM-Approved Terminal Test Kit in order to front probe terminals. Do not use paper clips or other substitutes to probe terminals.
When using the J-35616 GM-Approved Terminal Test Kit, ensure the terminal test adapter choice is the correct size for the connector terminal. Do not visually choose the terminal test adapter because some connector terminal cavities may appear larger than the actual terminal in the cavity. Using a larger terminal test adapter will damage the terminal. Refer to the J-35616 GM-Approved Terminal Test Kit label on the inside of the J-35616 GM-Approved Terminal Test Kit for the correct adapter along with the connector end view for terminal size.Notice: Do not operate the AIR pump for more than 60 seconds. Continuous operation of the AIR pump in excess of 60 seconds will damage the AIR pump.
If the problem is intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Powertrain On Board Diagnostic (OBD) System Check prompts you to complete some basic checks and store the freeze frame and failure records data on the scan tool.
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Listen for an audible click when the solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.
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Tests for voltage at the feed side of the solenoid.
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Verifies that the PCM is providing ground to the solenoid.
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Determines if ground is constantly being applied to the solenoid.
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The PCM utilizes an electrically erasable programmable read-only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | ||
Does the solenoid turn ON and OFF with each command? | -- | Go to Diagnostic Aids | Go to Step 3 | |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | -- | Go to Step 8 | Go to Step 5 | |
Does the test lamp remain illuminated with each command? | -- | Go to Step 7 | Go to Step 6 | |
6 | Test the control circuit of the solenoid for a short to voltage or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
7 | Test the control circuit of the solenoid for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Inspect for faulty connections at the solenoid. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
9 | Inspect for faulty connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 | Repair the feed circuit of the solenoid. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the solenoid. Did you complete the repair? | -- | Go to Step 13 | -- |
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Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair? | -- | Go to Step 13 | -- | |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
