Circuit Description
The DTC P1012 Rocker Arm Actuator System Stuck Off diagnostic monitors the operation of the rocker arm oil control solenoid. The rocker arm oil control solenoid enables the powertrain control module (PCM) to operate the high speed cam system. The high speed cam system significantly increases valve lift at engine speeds above 6,000 RPM. A second camshaft lobe with a high lift profile is cast into each camshaft, alongside the low/medium speed lobes. Unique rocker arms follow both the high speed and low/medium speed cam lobes. At engine speeds below 6,000 RPM, the low/medium speed cam lobes operate the rocker arms. When the rocker arm oil control solenoid is turned ON between 6,000-8,200 RPM, the rocker arms are operated by the high speed cam lobes. The rocker arm oil control solenoid is controlled by a pulse width modulated (PWM) signal from the PCM.
The rocker arm oil pressure switch detects oil pressure when oil is flowing thorough the rocker arm oil supply system. When the rocker arm oil control solenoid is ON, the oil pressure switch opens and the signal circuit to the PCM goes high. A DTC P1012 sets when the signal circuit of the rocker arm oil pressure switch remains low even when engine speed is more than 6,000 RPM. For additional information on the operation of the rocker arm oil control system refer to Rocker Arm Oil Control System Description .
Conditions for Running the DTC
| • | The engine has been running at least 10 seconds. |
| • | Engine speed is more than 6,000 RPM. |
| • | The engine coolant temperature (ECT) is at least 60°C (140°F). |
| • | The vehicle is operating at more than 10 km/h (6 mph). |
| • | DTC P1012 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | The signal circuit of the rocker arm oil pressure switch stays low. |
| • | The above condition is present for at least 1 second. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL). |
| • | 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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
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.
-
This step checks the operation of the rocker arm oil control solenoid. When commanded ON, the rocker arm oil control solenoid increases valve lift enough to cause the engine to run rough or to stall.
-
This step visually inspects the operation of the rocker arm oil control solenoid. The solenoid plunger and spool valve movement should be smooth and rapid from extended to retracted.
-
This step tests the operation of the rocker arm oil pressure switch. The oil pressure switch is normally closed to ground with less than 20.7 kPa (3 psi) of oil pressure. With the oil control solenoid energized oil pressure will open the switch and the test lamp should turn Off momentarily before the engine stalls.
-
This step checks for electrical resistance in the wiring and connections of the rocker arm oil control solenoid circuit. Circuit resistance as small as 25 ohms can cause the solenoid to malfunction and a DTC P1012 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 12 | ||||||
Does the engine idle very rough or stall when the rocker arm oil control solenoid is commanded ON? | -- | Go to Step 7 | Go to Step 4 | |||||||
Does the solenoid plunger extend to the specified value when voltage is applied and then retract smoothly when voltage is removed? | 3 mm (0.125 in) | Go to Step 5 | Go to Step 11 | |||||||
5 |
Is the rocker arm oil control solenoid oil filter restricted or blocked? | -- | Go to Step 10 | Go to Step 6 | ||||||
6 |
Did you complete the repair? | -- | Go to Step 15 | -- | ||||||
7 |
Is the voltage more than the specified value? | 11.0 V | Go to Step 8 | Go to Step 9 | ||||||
Did the test lamp turn OFF when the rocker arm oil control solenoid was commanded ON? | -- | Go to Intermittent Conditions | Go to Step 13 | |||||||
9 |
Did you find and correct a condition? | -- | Go to Step 15 | Go to Step 14 | ||||||
10 |
Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||
Did you find and correct a condition? | -- | Go to Step 15 | Go to Step 12 | |||||||
12 | Replace the rocker arm oil control solenoid valve. Refer to Rocker Arm Oil Control Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||
13 | Replace the rocker arm oil pressure switch. Refer to Rocker Arm Oil Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||
14 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||
15 |
Does the DTC run and pass? | -- | Go to Step 16 | Go to Step 2 | ||||||
16 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||
