Circuit Description
The powertrain control module (PCM) receives voltage pulses from the camshaft position (CMP) sensor. The PCM uses the pulses from the CMP sensor in order to identify cylinders and perform misfire diagnostics. The CMP sensor generates the voltage pulses from the rotation of the camshaft. A signal rotor, which rotates with the camshaft, passes through the magnetic field of the CMP sensor. The movement of the signal rotor past the sensor creates a flux in the magnetic field. The CMP sensor responds to the change in the magnetic field and sends this information to the PCM.
Conditions for Setting the DTC
| • | No signal from the CMP sensor while cranking the engine. |
| • | No signal from the CMP sensor when the engine is running. |
| • | The condition is present for 2 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL). |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer. |
Conditions for Clearing the MIL/DTC
| • | The MIL turns OFF after three consecutively passing trips without a fault present. |
| • | A History DTC clears after 40 consecutive warm-up cycles without a fault. |
| • | Use the scan tool Clear DTC Information function or disconnect the PCM battery feed in order to clear the DTC. |
Diagnostic Aids
Check the CMP sensor for damage or foreign material. Remove any metal particles attracted to the sensor end and recheck.
An intermittent malfunction may be caused by a fault in the CMP sensor electrical circuit. Inspect the wiring harness and components for any of the following conditions:
| • | Backed out terminals. |
| • | Improper mating of terminals. |
| • | Broken electrical connector locks. |
| • | Improperly formed or damaged terminals. |
| • | Faulty terminal to wire connections. |
| • | Physical damage to the wiring harness. |
| • | A broken wire inside the insulation. |
| • | Corrosion of electrical connections, splices, or terminals. |
If a DTC P0340 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.
Test Description
The numbers below refer to the step numbers in the Diagnostic Table.
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The Powertrain OBD system check 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.
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This step determines if fault is present.
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This step checks for reference voltage at the CMP sensor.
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This step checks the operation of the CMP sensor. Passing a magnetic material across the face of the CMP sensor simulates the movement of the signal rotor and should cause a response from the sensor. A good CMP sensor will switch back and forth from 0.0-1.0 volts to 4.0-5.0 volts when the magnetic field is cut by a metal object passing at a distance of approximately 1 mm (0.03 in).
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic System Check? | -- | |||||||||
Does the scan tool indicate a DTC P0340? | -- | Go to Diagnostic Aids | ||||||||
3 |
Is the voltage at the specified value? | B+ | ||||||||
Measure the voltage from the CMP sensor signal circuit (harness side) to ground with the DMM. Is the voltage within the specified value? | 4-5 volts | |||||||||
5 | Probe the CMP sensor ground circuit at the CMP sensor harness connector with a test lamp connected to B+. Did the test lamp illuminate? | -- | ||||||||
Does the DMM indicate that the CMP sensor signal is switching from the first specified value to the second specified value? | 0-1 volt 4-5 volts | |||||||||
7 |
Was a repair necessary? | -- | ||||||||
8 | Repair the open in the CMP sensor ignition feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||
9 | Repair the open or the faulty connection in the CMP sensor ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||
10 | Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement . Is the action complete? | -- | -- | |||||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | -- | |||||||
12 |
Was a repair necessary? | -- | Go to Diagnostic Aids | |||||||
13 |
Are any DTCs displayed on the scan tool? | -- | Go to the Applicable DTC Table | System OK |
