Refer to Engine Controls Schematics
Crankshaft and Camshaft Position Sensor
.
Circuit Description
The camshaft position (CMP) sensor has a power, ground (reference low) and a signal circuit. The powertrain control module (PCM) supplies 12 volts to the sensor. The PCM determines which pair of cylinders is at top dead center (TDC) using the crankshaft position (CKP) sensor data. The CMP sensor signal, when combined with the CKP sensor signal, enables the PCM to determine exactly which cylinder is on a firing stroke. The PCM can then properly synchronize the ignition system, fuel injectors, and knock control.
Conditions for Running the DTC
Engine cranking or running
Conditions for Setting the DTC
The PCM detects a problem with the CMP sensor signal.
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 MIL OFF after 3 consecutive drive trips during which the diagnostic runs and passes. |
| • | A last test failed, or the current DTC, clears when the diagnostic runs and passes. |
| • | A History DTC clears after 40 consecutive warm-up cycles, if no other emission related diagnostic failures are reported. |
| • | Use a scan tool in order to clear the MIL diagnostic trouble code. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description , Clearing Diagnostic Trouble Codes. |
Diagnostic Aids
Notice: 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
Ensure that the engine grounds are clean and tight, including the main battery ground cable at the engine block.
If no trouble is found with the CMP sensor or the related circuitry, and DTC P0340 continues to set, the engine should be checked for incorrect cam timing. Refer to Timing Chain in Engine Mechanical.
If the problem is intermittent, refer to Intermittent Conditions .
CKP/CMP sensor DTCs may set if the key is turned to Start and the starter is inoperative. If P0335, P0340, and P0385 are set and no trouble is found, check for the following:
| • | Is there a no-crank condition or an intermittent no-crank condition? |
| • | Was an attempt made to crank the engine with the shift lever not in P/N? |
DTC P0340 may set if engine cranking speed is below 120 RPM. Review Freeze Frame and Failure Records to determine if the DTC set during cranking with an engine speed of less than 120 RPM. If this was the case, correct the cause of the slow cranking speed. The scan tool parameter CMP Sensor Data will not display an accurate RPM value below 120 RPM.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
Does CMP Sensor Data indicate engine RPM and Cam Signal Present indicate Yes? | -- | Go to Step 3 | Go to Step 4 | |
3 | Move the related harnesses and connectors, by hand only, while monitoring the scan tool display. Does the Cam signal present display change to No or does CMP Sensor Data RPM become erratic? | -- | Go to Step 10 | Go to Diagnostic Aids |
4 |
Does the DMM indicate the specified voltage? | B+ | Go to Step 5 | Go to Step 11 |
5 | Connect the DMM between the power circuit and the ground circuit in the CMP sensor harness connector. Does the DMM indicate the specified voltage? | B+ | Go to Step 6 | Go to Step 12 |
6 |
Is RPM indicated on the scan tool? | -- | Go to Step 16 | Go to Step 7 |
7 |
Is voltage indicated? | -- | Go to Step 15 | Go to Step 8 |
8 | Using the DMM, check the signal circuit for continuity between the CMP sensor harness connector and the PCM harness connector. Does the DMM display the value shown or lower? | 5 ohms | Go to Step 9 | Go to Step 13 |
9 | Using the DMM, check for continuity between the signal circuit and ground. The DMM should display infinite resistance. Does the DMM display infinite resistance? | -- | Go to Step 18 | Go to Step 14 |
10 | Repair the harness and connections as necessary. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Is the action complete? | -- | Go to Step 20 | -- |
11 | Repair the sensor power circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 20 | -- |
12 | Repair the open or high resistance sensor ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 20 | -- |
13 | Repair the open or high resistance sensor signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 20 | -- |
14 | Repair the sensor signal circuit shorted to ground. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 20 | -- |
15 | Repair the sensor signal circuit shorted to power. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 20 | -- |
16 | Check for poor connections and terminal tension at the CMP sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Was a problem found and corrected? | -- | Go to Step 20 | Go to Step 17 |
17 | Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement . Is the action complete? | -- | Go to Step 20 | -- |
18 | Check for poor connections and terminal tension at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Was a problem found and corrected? | -- | Go to Step 20 | Go to Step 19 |
19 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 20 | -- |
20 |
Does the scan tool indicate that this test ran and passed? | -- | Go to Step 21 | Go to Step 2 |
21 | Review Captured Info using the scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to the applicable DTC table
| System OK |
