Circuit Description
The P0012 Intake Camshaft Position (CMP) System Performance - Retarded diagnostic monitors the operation of the camshaft position (CMP) actuator solenoid. The CMP actuator solenoid enables the powertrain control module (PCM) to change the intake camshaft timing while the engine is running. The CMP actuator solenoid contains a spool valve that controls the advance of the camshaft. The CMP actuator solenoid is controlled by a pulse width modulated (PWM) signal from the PCM. The CMP sensor monitors the camshaft position or the camshaft angle, and compares that position or phase to the crankshaft position (CKP) senor signal. The PCM determines whether the camshaft angle is correct by comparing the actual camshaft position to the target camshaft position. By continuously analyzing the input of the CMP sensor and the CKP sensor the PCM can detect a fault in the CMP actuator system. For additional information on the operation of the CMP actuator system refer to Camshaft Actuator System Description .
Conditions for Running the DTC
| • | The engine is running. |
| • | The engine coolant temperature (ECT) is more than 70°C (158°F). |
| • | Engine speed is 400-4,000 RPM |
| • | The vehicle speed is more than 8 km/h (5 mph). |
Conditions for Setting the DTC
| • | The PCM does not detect a change in the camshaft timing. |
| • | The PCM detects that the camshaft timing is fixed. |
| • | Either of the above conditions is present more than once when the CMP actuator solenoid is activated. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active. |
| • | The PCM stores the conditions that were present when the DTC set as Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present. |
| • | A DTC clears after 40 consecutive warm-up cycles have occurred without a fault. |
| • | A DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
Inspect for any of the following conditions:
| • | Inspect for any recent engine mechanical repairs. An incorrectly timed or incorrectly installed camshaft can cause a DTC P0012 to set. |
| • | Inspect the CMP sensor reluctor for a damaged tooth. A damaged reluctor can cause an incorrect CMP sensor reading that may set a false DTC P0012. |
| • | If a DTC P0012 and P0011 are both present, inspect for a malfunctioning CMP solenoid valve. Observe that the Cam Phase Angle and Cam Phase Angle Desired parameters on a scan tool are approximately equal. A difference in the two parameters indicates that the CMP solenoid may be sticking. |
| • | An intermittent DTC P0012 can be caused by a loss in the oil supply to the CMP solenoid valve or the CMP actuator assembly. Inspect the oil passages for foreign material and blockage. Inspect the oil filter of the CMP actuator solenoid valve for dirt or restrictions. Refer to Camshaft Position Actuator Solenoid Valve Filter Replacement . |
An intermittent malfunction may be caused by a fault in the electrical circuit of the CMP actuator valve. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .
The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step checks the operation of the CMP actuator system. When commanded ON, the CMP actuator solenoid advances the camshaft, usually causing the engine to stall.
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This step visually inspects the operation of the CMP actuator solenoid valve. The solenoid plunger and spool valve movement should be smooth and rapid from extended to retracted.
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This step checks for electrical resistance in the wiring and connections of the CMP actuator solenoid circuit. Circuit resistance as small as 15 ohms can cause the solenoid to malfunction and a DTC P0012 to set.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | ||
2 |
Is the resistance within the specified range? | 6.9-7.9 ohms at 20°C (68°F) | Go to Step 3 | Go to Step 10 |
Does the engine idle very rough or stall when the CMP actuator solenoid is commanded ON with the scan tool? | -- | Go to Diagnostic Aids | Go to Step 4 | |
Does the solenoid plunger extend to at least the specified value when voltage is applied and then retract when voltage is removed? | 3 mm (0.125 in) | Go to Step 5 | Go to Step 10 | |
5 |
Is the CMP actuator solenoid oil filter restricted or blocked? | -- | Go to Step 9 | Go to Step 6 |
6 |
Was a repair necessary? | -- | Go to Step 13 | Go to Step 7 |
Was the voltage within the first specified value with the solenoid OFF, and within the second specified value with the solenoid ON? | 0.7-1.0 V 8.0-10.0 | Go to Step 11 | Go to Step 8 | |
8 |
Was a repair necessary? | -- | Go to Step 13 | Go to Step 12 |
9 |
Is the action complete? | -- | Go to Step 13 | -- |
10 | Replace the CMP actuator solenoid valve. Refer to Camshaft Position Actuator Solenoid Valve Replacement . Is the action complete? | -- | Go to Step 13 | -- |
11 | Replace the CMP actuator assembly. Refer to Timing Chain and Sprocket Replacement in Engine Mechanical. Is the action complete? | -- | Go to Step 13 | -- |
12 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 13 | -- |
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 |
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
