GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Engine 🢒 Engine Controls - 4.6L (LH2) 🢒 DTC P0366 or P0391

Circuit Description

The exhaust camshaft position (CMP) sensor is a hall integrated circuit (IC) type sensor that works in conjunction with a single tooth reluctor wheel used to determine the position of the exhaust camshaft. The engine control module (ECM) supplies a 12-volt pull up voltage on the CMP sensor signal circuit. As the tooth on the reluctor wheel passes the CMP sensor, it sends a digital signal which is an image of the reluctor wheel, to the ECM. The ECM processes this information to determine the exact position of the camshafts, and to determine the optimum ignition and injection points of the engine. The CMP sensor wiring consists of a 12-volt reference circuit, a low reference circuit, and a signal circuit. If the ECM detects extra or missing CMP sensor signal transitions within a certain number of crankshaft revolutions, DTC P0336 or P0391 will set.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC P0366 Exhaust Camshaft Position (CMP) Sensor Performance Bank 1
    • DTC P0391 Exhaust Camshaft Position (CMP) Sensor Performance Bank 2

Conditions for Running the DTC
    • The engine is running.
    • DTC P0366 or P0391 runs continuously once the above condition is met.

Conditions for Setting the DTC

The ECM detects a signal from the CMP sensor, but the number of pulses are less than or more than what is expected during one crankshaft revolution for more than 1 second.

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.

Test Description

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

  1. This step verifies that the condition is present.

    2.

  2. This step detects if there is electromagnetic interference (EMI) on the CMP sensor circuits.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn ON the ignition, with the engine OFF.
  2. Clear the DTCs with a scan tool.
  3. Start the engine.
  4. Observe the DTC information with a scan tool.

Did DTC P0366 or P0391 fail this ignition?

Go to Step 3

Go to Step 4

3

Did any other DTCs fail this ignition cycle?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 5

4
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 5

Go to Intermittent Conditions

5

Inspect the camshaft position (CMP) sensor circuits for the following conditions:

    • For being routed too close to the ignition coils
    • For being routed too close to after-market electrical equipment
    • For being routed too close to solenoids, relays, and motors

Did you find and correct the condition?

Go to Step 10

Go to Step 6

6

Test for an intermittent and for a poor connection at the affected CMP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

7

Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

8
  1. Remove the affected CMP sensor. Refer to Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust or Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust .
  2. Inspect the CMP sensor and the camshaft actuator reluctor wheel for the following conditions:
    3. • Incorrect sensor installation
    • A cracked or damaged sensor
    • The sensor coming in contact with the reluctor wheel
    • Excessive air gap between the reluctor wheel and the sensor
    • Foreign material passing between the sensor and the camshaft reluctor wheel
    • Camshaft reluctor wheel damage
  3. If you find a condition with the CMP sensor or the camshaft reluctor wheel refer to one of the following procedures:

Did you find and correct the condition?

Go to Step 10

Go to Step 9

9

Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust or Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust .

Did you complete the replacement?

Go to Step 10

--

10
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 11

11

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK