Circuit Description
The camshaft position (CMP) sensor correlates the crankshaft to CMP so that the powertrain control module (PCM) can determine which cylinder is ready to be fueled by the injector. The CMP sensor also determines which cylinder is misfiring when a misfire is present. If the PCM receives an intermittent signal from the CMP, then the CMP Resync Counter will increment. When the PCM cannot use the information from the CMP sensor, a DTC is set and the PCM will fuel the engine by using the alternating synchronous double fire (ASDF) method.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The CMP Active Counter is not incrementing.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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
| • | Whenever the PCM sees less than 15 resyncs in 256 seconds, the counter resets to 0. Any time a poor connection is present, the CAM sensor active counter stops incrementing and the CAM sensor resync counter starts to increment. |
| • | Inspect the wiring harness for damage. If the harness appears to be OK, observe the CMP resync counter on the scan tool while moving connectors and wiring harnesses related to the CMP sensor. If the CMP resync counter still does not count, operate any non-engine related electrical components on the vehicle, while observing the scan tool. A change in display will indicate the location of the malfunction. |
| • | A defective reluctor wheel or a cracked or damaged CMP sensor can result in an intermittent. Remove the CMP sensor and inspect for any damage. With the CMP sensor removed, you can also inspect the reluctor wheel through the hole. Inspect the porosity and condition of the wheel. The edges must be square, look for a nicked or damaged wheel. |
If this DTC is determined to be intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines if there is a problem with the signal circuit.
-
If the fuse is open in the jumper wire, there is a short to ground on the signal circuit.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate the CMP Active Counter is incrementing? | -- | Go to Step 3 | Go to Step 4 |
3 |
Does the DTC reset? | -- | Go to Step 4 | Go to Diagnostic Aids |
4 |
Does the voltage measure near the specified value? | B+ | Go to Step 6 | Go to Step 5 |
5 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 |
6 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 7 |
7 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 |
Does the CAM signal change EACH time the signal circuit is touched? | -- | Go to Step 14 | Go to Step 9 | |
Did the fuse in the jumper wire open? | -- | Go to Step 11 | Go to Step 10 | |
10 | Test the signal circuit of the CMP sensor for a short to voltage or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 |
11 | Test the signal circuit of the CMP sensor for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 |
12 | Inspect for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
13 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- |
14 | Inspect for poor connections at the CMP sensor. Refer to Wiring Repairs in Wiring Systems Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 |
15 | Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- |
16 |
Does the DTC run and pass? | -- | Go to Step 17 | Go to Step 2 |
17 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
