DTC P0343 Camshaft Position (CMP) Sensor Circuit High Voltage. GMC Truck GMC K Sierra

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Sierra - 4WD 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC P0343 Camshaft Position (CMP) Sensor Circuit High Voltage

Engine Controls Component Views
Cell 21: P100, Camshaft Position Sensor, Crankshaft Position Sensor, and Knock Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Camshaft Position sensor is mounted through the top of the engine block at the rear of the valley cover. The CMP sensor works in conjunction with a 1X reluctor wheel on the camshaft. The reluctor wheel is inside the engine immediately in front of the rear cam bearing. The PCM provides a 12 volt power supply to the CMP sensor as well as a ground and a signal circuit.

The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic for the Camshaft Position sensor checks for a loss of Camshaft Position sensor signal.

Observe that as long as the PCM receives the Crankshaft Position sensor 24X signal, the engine will start. The PCM can determine top dead center for all cylinders by using the Crankshaft Position sensor 24X signal alone. The Camshaft Position sensor 1X signal is used by the PCM to determine if the cylinder at top dead center is on the firing stroke, or the exhaust stroke. The system attempts synchronization and looks for an increase in engine speed indicating the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes it incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.

Conditions for Running the DTC

The engine speed is less than 4000 RPM.

Conditions for Setting the DTC

The PCM detects the Cam signal is stuck high when the signal should be low for 1.5 seconds.

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 OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

•	A last test failed, or current DTC, clears when the diagnostic runs and does not fail.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

•	Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

The following conditions may cause this DTC to set:

•	Poor connections/terminal tension at the sensor

•	Camshaft reluctor wheel damage

•	The sensor coming in contact with the reluctor wheel

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.

The CMP sensor output can be tested. The sensor must be supplied with a power and a ground. The engine must be cranking to perform this test. You can measure the duty cycle at the signal circuit of the sensor. The duty cycle should be between 45-55% for a good sensor.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

This step verifies that the fault is present. A hard start is observed when a malfunction is present.

This step tests the Camshaft Position sensor ignition feed circuit from the PCM to the CMP.

This step tests the Camshaft Position sensor ground circuit from the PCM to the CMP.

This step tests the Camshaft Position sensor signal circuit. Applying a voltage causes the CAM signal input - High to Low and Low to High parameter to increase if the circuit and the PCM are operating properly.

This step tests the Camshaft Position sensor ignition feed circuit from the PCM to the CMP sensor.

This step tests the Camshaft Position sensor ground circuit from the PCM to the CMP sensor.

Step

Action

Value(s)

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Install a scan tool.
Idle the engine.
Monitor the CAM signal input - High to Low and Low to High transition parameter in the Engine Data List 1 using the scan tool.

Does the scan tool parameter increment?

Go to Step 3

Go to Step 4

Turn ON the ignition leaving the engine OFF.
Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
Turn OFF the ignition for 15 seconds.
Idle the engine.
Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, then enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

Go to Step 4

Go to Diagnostic Aids

Turn OFF the ignition.
Disconnect the Camshaft Position Sensor (CMP).
Turn ON the ignition leaving the engine OFF.
Measure the Camshaft Position sensor ignition feed voltage using the DMM J 39200 connected to battery ground.

Does the DMM display near the specified value?

B+

Go to Step 5

Go to Step 7

Measure the voltage from the Camshaft Position sensor ignition feed circuit to the Camshaft Position sensor ground circuit using the DMM J 39200 .

Does the DMM display near the specified voltage?

B+

Go to Step 6

Go to Step 9

Start the engine.
Monitor the CAM signal input - High to Low and Low to High transition in the Engine Data List 1 using the scan tool.
Momentarily and repeatedly probe the signal circuit with the test lamp J 35616-200 connected to B+.

Does the CAM signal input - High to Low and Low to High transition counters increment when the test lamp contacts the signal circuit?

Go to Step 15

Go to Step 10

Turn OFF the ignition.
Disconnect the PCM connector C2 located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module Replacement/Programming .
Test the continuity of the CMP ignition feed circuit using the DMM J 39200 . Refer to Testing for Continuity in Wiring Systems.

Is there continuity and is the resistance within the specified range?

0-5ohms

Go to Step 8

Go to Step 12

Inspect the CMP ignition feed circuit for the following:

•	A grounded circuit

•	A poor connection

Did you find and correct the condition?

Go to Step 19

Go to Step 16

Turn OFF the ignition.
Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement/Programming .
Test the continuity of the CMP ground circuit using the DMM J 39200 . Refer to Testing for Continuity in Wiring Systems.

Is there continuity and is the resistance within the specified range?

0-5ohms

Go to Step 16

Go to Step 13

Turn OFF the ignition.
Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement/Programming .
Test the continuity of the CMP signal circuit using the DMM J 39200 . Refer to Testing for Continuity in Wiring Systems.

Is there continuity and is the resistance within the specified range?

0-5ohms

Go to Step 11

Go to Step 14

Turn ON the ignition leaving the engine OFF.
Test the CMP signal circuit for the following:

•	A grounded circuit

•	A circuit shorted to a voltage

Did you find and correct the condition?

Go to Step 19

Go to Step 16

Inspect the CMP ignition feed circuit for an open.
If you find an open circuit , repair the CMP ignition feed circuit. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 16

Repair the CMP ground circuit for an open. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

Go to Step 19

Repair the CMP signal circuit for an open. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

Go to Step 19

Inspect for poor connections at the CMP harness connector. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If you find a poor connection repair the connector as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 17

Inspect the PCM harness connector for poor connections. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If you find a poor connection repair the connector as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 18

Replace the Camshaft Position sensor. Refer to Camshaft Position Sensor Replacement .

Is the action complete?

Go to Step 19

Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

Go to Step 19

Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

Go to Step 20

Go to Step 2

Select the Capture Info option and the Review Info option using the scan tool.

Does the scan tool display any DTCs that you have not diagnosed?

Go to applicable DTC Table

System OK