Circuit Description
The hall effect camshaft position (CMP) sensor produces 3 ON-OFF pulses for each revolution of the camshaft. The CMP output is pulse width encoded. The engine control module (ECM) uses the CMP and crankshaft position (CKP) output pulses to determine the engine speed and position. The CMP is connected directly to the ECM by the following circuits:
| • | 5-volt reference |
| • | Low reference |
| • | CMP sensor signal |
If the ECM does not see a CMP signal for more than 2 seconds, DTC P0340 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0340 Camshaft Position (CMP) Sensor Circuit
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The engine is turning faster than 60 RPM. |
Conditions for Setting the DTC
The ECM does not see a CMP sensor signal for more than 2 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | An intermittent CMP sensor signal may cause DTC P0340 to set. Wiggle the wiring harness with the engine running and observe the Cam Signal Missed parameter of the scan tool. If the parameter indicates anything other than 0, there is an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections and Inducing Intermittent Fault Conditions in Wiring Systems. |
| • | If the CMP sensor signal is lost while running, the engine will operate normally. If the CMP sensor signal is not present on start-up, the engine will not start. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
If the engine starts and runs, the condition is suspected to be intermittent. If there is a condition with the CMP sensor circuit, the vehicle will not run.
-
Inspect the CMP sensor for physical damage. The camshaft may damage the sensor.
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||||||||
Attempt to start the engine. Does the engine start and run? | -- | Go to Diagnostic Aids | Go to Step 3 | |||||||||||
3 |
Does the DMM display a reading within the specified range? | 4.8-5.2 V | Go to Step 5 | Go to Step 4 | ||||||||||
4 | Does the DMM display a reading above the specified value? | 5.2 V | Go to Step 9 | Go to Step 8 | ||||||||||
5 |
Is the resistance above the specified value? | 5 ohms | Go to Step 10 | Go to Step 6 | ||||||||||
6 |
is the voltage more than the specified value? | 0.2 V | Go to Step 11 | Go to Step 7 | ||||||||||
7 |
Does the Cam Signal Present parameter change when the test lamp contracts the signal circuit? | -- | Go to Step 12 | Go to Step 13 | ||||||||||
8 | Test the CMP sensor 5-volt reference circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 | ||||||||||
9 | Test the CMP sensor 5-volt reference circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 | ||||||||||
10 | Repair the high resistance in the CMP sensor 5-volt reference circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 18 | -- | ||||||||||
11 | Test the CMP sensor low reference circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 | ||||||||||
12 | Test the CMP sensor signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 14 | ||||||||||
13 | Test the CMP sensor signal for the following conditions:
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 | ||||||||||
14 | Inspect for poor connections at the CMP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 16 | ||||||||||
15 | Inspect for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 | ||||||||||
|
Important: Inspect the CMP sensor for physical damage before replacing. Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- | |||||||||||
17 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||||||
18 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 19 | ||||||||||
19 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||||
