GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0340: Intake Camshaft Position (CMP) Sensor Circuit Bank 1

DTC P0341: Intake Camshaft Position (CMP) Sensor Performance Bank 1

DTC P0345: Intake Camshaft Position (CMP) Sensor Circuit Bank 2

DTC P0346: Intake Camshaft Position (CMP) Sensor Performance Bank 2

DTC P0365: Exhaust Camshaft Position (CMP) Sensor Circuit Bank 1

DTC P0366: Exhaust Camshaft Position (CMP) Sensor Performance Bank 1

DTC P0390: Exhaust Camshaft Position (CMP) Sensor Circuit Bank 2

DTC P0391: Exhaust Camshaft Position (CMP) Sensor Performance Bank 2

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

The 5-Volt Reference Circuit

P0069, P0107, P0340, P0345, P0365, P0390, P0452, P0522, P0532, P0641, P1183, P2228

P0340, P0345, P0365, P0390

P0641

--

CMP Sensor Signal Circuit

P0340, P0345, P0365, P0390,

P0340, P0345, P0365, P0390

P0340, P0345, P0365, P0390

P0341, P0346, P0366, P0391

Low Reference Circuit

--

P0340, P0345, P0365, P0390

P0340, P0345, P0365, P0390

--

Circuit Description

The camshaft position (CMP) sensor circuits consist of an engine control module (ECM) supplied 5-volt reference circuit, low reference circuit and an output signal circuit. The CMP sensor is an internally magnetic biased digital output integrated circuit sensing device. The sensor detects magnetic flux changes of the teeth and slots of a 4-tooth reluctor wheel attached to the camshaft. As each reluctor wheel tooth rotates past the CMP sensor, the resulting change in the magnetic field is used by the sensor electronics to produce a digital output pulse. The sensor returns a digital ON/OFF DC voltage pulse of varying frequency, with 2 narrow and 2 width output pulses per camshaft revolution that represent an image of the camshaft reluctor wheel. The frequency of the CMP sensor output depends on the velocity of the camshaft. The engine control module (ECM) decodes the narrow and wide tooth pattern to identify camshaft position. This information is then used to sequence the ignition timing and fuel injection events of the engine. The ECM also uses CMP sensor output information to determine the camshaft relative position to the crankshaft, to control the CMP actuator if equipped, and for limp-home operation.

Conditions for Running the DTC

P0340, P0345, P0365, P0390

    • The crankshaft has synchronized and the DTC of 5-volt reference voltage is not set.
    • The engine is cranking or running.
    • The CMP sensor pulses is received or intake MAF is more than 3 g/s.

P0341, P0346, P0366, P0391

The crankshaft has synchronized and the DTC of 5-volt reference voltage is not set.

Conditions for Setting the DTC

P0340, P0345, P0365, P0390

    • When the engine rotates 2 revolution first, CMP sensor pulse is not received.
    • The ECM detects that the starter is commanded ON and the engine has been cranking and detects the rotation for more than 4 seconds without receiving a CMP sensor pulse.
    • The ECM detects that the engine is running for more than 4 seconds without receiving a CMP sensor pulse.
    • The ECM detects that the engine is running, without receiving CMP sensor pulses in 8 times of 10 tests in per 100 engine cycles

P0341, P0346, P0366, P0391

The ECM detects the following conditions:

    • When the engine cranks 2 revolution first, detects that CMP sensor pulses is less than 4 or more than 10.
    • The ECM detects that the engine is running, but in per 100 engine cycles, receives CMP sensor pulses during 397-403 periods.

Action Taken When the DTC Sets

    • DTCs P0340, P0341, P0345, P0346, P0365, P0366, P0390 and P0391 are Type B DTCs.
    • The CMP actuator is commanded to the Stop position.
    • When one intake camshaft position sensor exists malfunction, it will stop the both intake camshaft actuators. When one exhaust camshaft position sensor exists malfunction, it will stop the both exhaust camshaft actuators.

Conditions for Clearing the DTC

DTCs P0340, P0341, P0345, P0346, P0365, P0366, P0390 and P0391 are Type B DTCs.

Diagnostic Aids

With a DTC set, the engine may crank for an extended period of time during start-up.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Controls Connector End Views
    •  Engine Control Module Connector End Views

Description and Operation

Electronic Ignition (EI) System Description

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Engine Control Module Scan Tool Information

Special Tools

J 35616 Connector Test Adapter Kit

Circuit/System Verification

  1. Ignition OFF, inspect the engine wiring harness carrying the CMP sensor circuits for the following conditions:
  2. • Close routing of aftermarket electrical equipment
    • Close to solenoids, motors, and relays
         ⇒Correct any wire harness routing or component placement conditions, if it is determined to be a possible source of electrical interference.
  3. Observe the following parameters for increasement:
  4. • Exhaust CMP Bank 1 Active
    • Intake CMP Bank 1 Active
    • Exhaust CMP Bank 2 Active
    • Intake CMP Bank 2 Active
         ⇒If any of these parameters stops increment, continue with the Circuit/System Testing.
         ⇒If the vehicle passes the Circuit/System Verification Test, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle under the conditions observed from the Freeze Frame/Failure Records.

Circuit/System Testing

P0340, P0345, P0365, P0390

  1. Ignition OFF, disconnect the appropriate camshaft position (CMP) sensor wire harness connector.
  2. Test for less than 1 ohm between the low reference circuit terminal B and ground on the CMP.
  3. If more than the specified values, test the low reference circuit for an open/high resistance. If the circuit test normal, replace the ECM.
  4. Ignition ON, test for 4.8-5.2 volts between the CMP 5-volt reference circuit terminal A and ground.
  5. If less than the specified range, test the 5-volt reference circuit for an open, high resistance or short to ground. If the circuit test normal, replace the ECM.
    If greater than the specified range, test the 5-volt reference circuit for short to voltage. If the circuit test normal, replace the ECM.
  6. Ignition ON, test for 4.8-5.2 volts between the CMP signal circuit terminal C and ground.
  7. If less than the specified range, test the signal circuit for an open, high resistance or short to ground. If the circuit test normal, replace the ECM.
    If greater than the specified range, test the signal circuit for short to voltage. If the circuit test normal, replace the ECM.
  8. Ignition OFF, connect a fused jumper wire to the CMP signal circuit terminal C on the CMP sensor harness connector.
  9. Ignition ON, momentarily touch the other end of the fused jumper wire to the ground. The CMP active counter parameter on the scan tool should be multiplied according to the time of ground.
  10. If the CMP active counter increases, replace the CMP sensor.
    If the CMP active counter does not increase, replace the ECM.

P0341, P0346, P0366, P0391

  1. Ignition OFF, inspect the CMP sensor for correct installation.
  2. If the CMP sensor is loose, inspect the sensor and the O-ring for damage, replace as necessary.
  3. Inspect the engine for the following conditions:
  4. • Engine oil for debris
    • Camshaft reluctor wheel damage
    • The timing chain, tensioner and sprockets for wear or damage
         ⇒If debris is found in the engine oil, inspect the internal engine components to determine the root cause. Repair or replace any worn or damaged components.

Component Testing

Important:  You must perform the Circuit/System Testing before proceeding with Component Testing.

  1. Inspect the CMP sensor for correct installation. Remove the CMP sensor from the engine and inspect the sensor and the O-ring for damage.
  2. If the sensor is loose, incorrectly installed, or damaged, replace the CMP sensor.
  3. Connect the CMP sensor harness connector to the CMP sensor.
  4. Turn the ignition to ON with the engine OFF. Observe the CMP Active Counter parameter on the scan tool.
  5. Pass a flat steel object repeatedly across the tip of the sensor that faces the reluctor wheel. The CMP Active Counter parameter should increase with each pass of the steel object.
  6. If the parameter does not increase, replace the CMP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust
    •  Camshaft Position Sensor Replacement - Bank 2 (Left Side) Intake
    •  Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust
    •  Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake