Circuit Description
The Camshaft Position (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. The CMP sensor has a power, ground (reference low) and a signal circuit. The PCM supplies 12 Volts to the sensor. The power and reference low circuits are also connected to the CKP sensor.
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 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. |
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 .
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 excessively slow (below 120 RPM). Review Freeze Frame/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
Number(s) below refer to the step number(s) on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||
Does the engine start and run? | -- | |||||||
3 |
Does CMP Sensor Data indicate engine RPM and Cam Signal Present indicate Yes? | -- | ||||||
4 | 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? | -- | Refer to Diagnostic Aids. | |||||
5 |
Does the DMM indicate the specified voltage? | B+ | ||||||
6 | Connect DMM J 39200 between the power circuit and the ground circuit in the CMP sensor harness connector. Does the DMM indicate the specified voltage? | B+ | ||||||
7 |
Does the DMM indicate the specified voltage? | B+ | ||||||
8 | Connect DMM J 39200 between the power circuit and the Ref Lo circuit in the CMP sensor harness connector. Does the DMM indicate the specified voltage? | B+ | ||||||
9 |
| -- | ||||||
10 |
Is voltage indicated? | -- | ||||||
11 | Using DMM J 39200 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 | ||||||
12 | Using DMM J 39200 , check for continuity between the signal circuit and ground. The DMM should display infinite resistance. Does the DMM display infinite resistance? | -- | ||||||
13 | Repair the harness/connections as necessary. Refer to Intermittents and Poor Connections Diagnosis . Is the action complete? | -- | -- | |||||
14 | Repair the open/high resistance power circuit . Is the action complete? | -- | -- | |||||
15 | Repair the open/high resistance ground circuit. Is the action complete? | -- | -- | |||||
16 | Repair open/high resistance sensor signal circuit. Is the action complete? | -- | -- | |||||
17 | Repair the sensor signal circuit shorted to ground. Is the action complete? | -- | -- | |||||
18 | Repair the sensor signal circuit shorted to power. Is the action complete? | -- | -- | |||||
19 | Check for poor connections/terminal tension at the CMP sensor. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found and corrected? | -- | ||||||
20 | Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement . Is the action complete? | -- | -- | |||||
21 | Check the power circuit for the following conditions:
Was a problem found and corrected? | -- | ||||||
22 | Check the ground circuit for an open/high resistance between the PCM and the splice. Was a problem found and corrected? | -- | ||||||
23 | Check for poor connections/terminal tension at the PCM. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found and corrected. | -- | ||||||
24 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |||||
25 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||
26 | Review Captured Info using the scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to the applicable DTC table
| System OK |
