Mechanics

P0412

2000 Buick Lesabre • 117,000 miles

P0412 code on my 2000 buick lesabre? What is that

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Dom777
May 31, 2012.




Diagnostic Chart

Schematic

CIRCUIT DESCRIPTION
Ignition Voltage is supplied directly to the AIR vacuum control solenoid. The 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 low (near 0 volts ). When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high (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 9.0 and 18.0 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 tails. 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 MIL Oft after three consecutive drive trips that the diagnostic runs and does not fail.
A last test failed (current DTC) clears when the diagnostic runs and does not fail.
A History DTC clears after forty 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. Refer to Powertrain Control Module (PCM) Description, Clearing Diagnostic Trouble Codes. See: Powertrain Management Computers and Control Systems Testing and Inspection Reading and Clearing Diagnostic Trouble Codes Clearing Diagnostic Trouble Codes

DIAGNOSTIC AIDS

NOTE: Use the connector test adapter kit J 35616-A for any test that requires probing the following items: The PCM harness connectors
The electrical center fuse/relay cavities
The component terminals
The component harness connector

Using this kit will prevent damage caused by the improper probing of connector terminals.

NOTE: 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. See: Powertrain Management Computers and Control Systems Testing and Inspection Initial Inspection and Diagnostic Overview Diagnostic Strategies Intermittent Conditions

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.

The powertrain OBD System Check prompts you to complete some basic checks and store the freeze frame and failure records data on the scan tool.
Listen for an audible click when the solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.
Tests for voltage at the feed side of the solenoid.
Verifies that the PCM is providing ground to the solenoid.
Tests if ground is constantly being applied to the solenoid.

The PCM utilizes Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.

Secondary air pump issue. Lots of checks needed that require a scan tool.

Roy

ASEMaster6371
May 31, 2012.


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