Page 1 of 5 1999 Buick Century Century, Regal VIN W Service Manual Document ID: 345654 DTC P0341 Camshaft Position (CMP) Sensor Performance Circuit Description During cranking, the Ignition Control Module (ICM) monitors the 7X crankshaft position sensor signal. Once the ICM determines spark synchronization, 3X reference signals are sent to the PCM. The PCM will command all six injectors ON for one priming shot of fuel in all cylinders. After the priming, the injectors are left OFF for the next six fuel control reference signals (two crankshaft revolutions). This allow each cylinder a chance to use the fuel from the priming shot. During this waiting period, a cam pulse will have been received by the PCM. The PCM uses the Cam signal pulses to initiate sequential fuel injection. The PCM constantly monitors the number of pulses on the Cam signal circuit and compares the number of Cam pulses to the number of 24X reference pulses and the number of 3X reference pulses being received. If the PCM receives an incorrect number of pulses on the Cam reference circuit, DTC P0341 will set and the PCM will initiate injector sequence without the Cam signal with a one in six chance that injector sequence is correct. The engine will continue to start and run normally, although the misfire diagnostic will be affected if a misfiring condition occurs. Conditions for Running the DTC The engine is running (3X reference pulses are being received). 2010 General Motors. All rights reserved.
Page 2 of 5 Conditions for Setting the DTC CMP sensor reference pulse is not detected every engine cycle. 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 will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. The DTC can be cleared by using a scan tool. Diagnostic Aids DTC P0341 can be caused by secondary components leaking high voltage into the ignition module. Check for the following conditions: Incorrect harness routing near secondary ignition component. Ignition coil arcing to wiring harness or Ignition Control Module (check ignition coils for cracks, carbon tracking, or other signs of damage). Secondary ignition wire(s) arcing to wiring harness. Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion. Poor terminal connection. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis, and Connector Repairs Wiring Systems. Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems. Inspect the PCM and the engine grounds for clean and secure connections.
Page 3 of 5 If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set. Test Description Number(s) below refer to the step number(s) on the Diagnostic Table: 8. The Cam Signal on the scan tool should change each time the signal circuit is touched. 9. If the fuse blows in the jumper wire, there is a short to ground on the signal circuit. 16. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed. Step 1 2 Action Did you perform the Powertrain On Board Diagnostic (OBD) System Check? 1. Turn the ignition on. 2. Review and record scan tool fail records data. 3. Operate vehicle within fail records condtion as noted. 4. Using a scan tool, monitor specific DTC info for DTC P0341 until DTC P0341 test runs. Value (s) Yes No Go to Step 2 Go to Powertrain On Board Diagnostic (OBD) System Check Does scan tool indicate DTC P0341 failed this ignition? 3 Go To Diagnostic Aids 3 Using the scan tool monitor Cam Signal. Is Cam Signal Present? Go To Diagnostic Aids 4 4 2. Disconnect the CMP sensor connector. 3. Turn the ignition on, leaving the engine off. 4. Using J 39200 DMM, check for voltage at CMP sensor feed circuit. B+ Does J 39200 DMM display a voltage near the specified value? 6 5 5 2. Disconnect the PCM. 3. Check for an open or short to ground in the CMP sensor feed circuit, repair as 16 12
Page 4 of 5 6 1. Connect an J 35616-200 test lamp to battery positive voltage. 2. Touch CMP sensor ground circuit. Does J 35616-200 test lamp light? 8 7 7 2. Disconnect the PCM. 3. Check for an open in the CMP sensor ground, if a problem is found repair as 16 12 8 1. Start the engine. 2. Monitor Cam Signal on the scan tool. 3. Using a 5 amp fused jumper wire connected to battery positive voltage momentarily touch the signal circuit 5 times for a duration of 1 second each. Does Cam Signal change EACH time the signal circuit is touched? 14 9 9 Did the fuse in the jumper wire blow? 11 10 10 Check signal circuit for an open or a short to voltage, if a problem is found repair as 16 12 11 Check signal circuit for a short to ground, if a problem is found repair as necessary. Refer to Wiring Repairs. 16 12 12 Check connections at PCM and replace terminals as necessary. Refer to Testing for Continuity, Intermittents and Poor Connections Diagnosis, Repairing Connector Terminals and Connector Repairs. Did any terminals require replacement? 16 13 Important: : Replacement PCM must be programmed. 13 Replace the PCM. Refer to Powertrain Control Module Replacement/Programming. Is the action complete? 16 14 Check connections at CMP sensor and replace terminals as necessary. y. Refer to Testing for Continuity, Intermittents and Poor Connections Diagnosis, Repairing Connector Terminals and
Page 5 of 5 Connector Repairs. Did any terminals require replacement? 16 15 15 Replace CMP sensor. Refer to Camshaft Position Sensor Replacement. Is the action complete? Go to Step 16 16 1. Review and record fail records data. 2. Clear DTCs. 3. Operate vehicle within fail records parameters as noted. 4. Using scan tool monitor Specific DTC for DTC P0341 until the DTC P0341 test runs. Does scan tool indicate DTC P0341 failed this ignition? 2 System OK