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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2005 🢒 TopKick C-Series (Conventional) C6/C7/C8 🢒 Restraints 🢒 SIR 🢒 DTC P0385

Circuit Description

The camshaft position (CMP) sensor is installed on the cylinder head at the rear of the camshaft gear. The CMP sensor has the following circuits:

    • A 12-volt reference circuit
    • A CMP sensor signal circuit

The engine control module (ECM) supplies 12 volts to the CMP sensor on the 12-volt reference circuit. The CMP sensor provides a signal to the ECM on the CMP signal circuit. The CMP sensor detects a total of 7 through holes, 6 holes arranged equally at every space, and one reference hole on the camshaft gear flange surface, and sends signals to the ECM. Receiving these signals, the ECM determines cylinder #1 compression top dead center (TDC). If the ECM detects the CMP sensor signals are not generated, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0385 Crankshaft Position (CKP) Sensor B Circuit

Conditions for Running the DTC

The crankshaft speed sensor signal is OK.

Conditions for Setting the DTC

The camshaft speed sensor signals are not generated during 10 engine rotations.

Action Taken When the DTC Sets
    • The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

Conditions for Clearing the DTC
    • The MIL resets when the ignition is turned OFF.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • Clear the MIL and the DTC with a scan tool.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Test the camshaft position (CMP) sensor 12-volt reference circuit between the engine control module (ECM) and the CMP sensor for the following conditions:
    2. • A short to CMP sensor signal circuit
    • An open circuit
  2. Repair the circuits, as necessary.

Did you find and correct the condition?

Go to Step 11

Go to Step 3

3
  1. Test the CMP sensor 12-volt reference circuit between the ECM and the CMP sensor for the following conditions:
    2. • A short to ground circuit
    • A short to voltage circuit
    • An open circuit
  2. Repair the circuits, as necessary.

Did you find and correct the condition?

Go to Step 11

Go to Step 4

4
  1. Test the CMP sensor circuit between the ECM and the CMP sensor for an open circuit.
  2. Repair the circuits, as necessary.

Did you find and correct the condition?

Go to Step 11

Go to Step 5

5
  1. Inspect for installation of the CMP sensor.
  2. Repair the installation, as necessary.

Did you find and correct the condition?

Go to Step 11

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Disconnect the CMP sensor connector.
  3. Inspect for connections at the harness connector of the CMP sensor.
  4. Repair the connections, as necessary.

Did you find and correct the condition?

Go to Step 11

Go to Step 7

7
  1. Observe the 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 8

Go to Intermittent Conditions

8

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

Did you complete the replacement?

Go to Step 9

--

9
  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 10

Go to Step 12

10

Important: The new ECM must be programmed.

Replace the ECM. Refer to Engine Control Module Programming and Setup , Engine Control Module Replacement/Restore Fuel Rate Data , and Fuel Injector Flow Rate Programming .

Did you complete the replacement?

Go to Step 11

--

11
  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 12

12

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

System OK