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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Grand Am 🢒 Engine 🢒 Engine Controls - 2.4L 🢒 DTC P0340 CMP Sensor Circuit Low Input

Object Number: 621245 Size: SF
Engine Controls Components
Power, Ground, KS, CMP, CKP, Coils, and ICM
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Circuit Description

The camshaft position (CMP) sensor correlates the crankshaft to camshaft position so that the Powertrain Control Module (PCM) can determine which cylinder is ready to be fueled by the injector. The CMP sensor also determines which cylinder is misfiring when a misfire is present. If the PCM receives an intermittent signal from the CMP, the CMP Resync Counter will increment. When the PCM cannot use the information from the CMP sensor, a DTC is set and the PCM will fuel the engine using the Alternating Synchronous Double Fire (ASDF) method.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The CMP Active Counter is not incrementing.

Action Taken When the DTC Sets
    • The malfunction indicator lamp (MIL) will illuminate after 2 consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time when the diagnostic fails. This information stores in the Freeze Frame and Failure Records buffers.
    • A history DTC stores.
    • The coolant fan turns on.

Conditions for Clearing the MIL/DTC
    • The MIL will turn off after 3 consecutive ignition cycles in which the diagnostic runs without a fault.
    • A history DTC will clear after 40 consecutive warm up cycles without a fault.
    • Use a scan tool to clear the DTCs.

Diagnostic Aids
    • An intermittent problem may be caused by the following conditions:
       - A poor electrical connection
       - A rubbed-through wire insulation
       - A broken wire inside the insulation
    • Thoroughly inspect any suspected circuitry for the following conditions:
       - Any backed out terminals
       - Any incorrect mating
       - Any broken locks
       - Any incorrectly formed connectors
       - Any damaged terminals
       - Any poor terminal-to-wiring connections
       - Any physical damage to the wiring harness

Test Description

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

  1. This step determines if the DTC P0342 is the result of a hard malfunction or an intermittent condition.

    2.

  2. This step determines if the voltage is available to the CMP sensor through the PCM.

    3.

  3. This step determines if the voltage is available to the CMP sensor through the PCM.

    4.

  4. This step tests the output of the CMP sensor. If there is a varying voltage, then the problem is in the CMP signal circuit. If there is no varying voltage, then problem is in the CMP sensor electrical connections or is a malfunctioning CMP sensor.

    5.

  5. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.

DTC P0340-Camshaft Position (CMP) Sensor Circuit Low Input

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Start the engine and idle the engine.
  2. Observe the CMP Active counter with the scan tool.

Does the CMP Active counter increment?

--

Go to Step 3

Go to Step 4

3

Operate the vehicle within the Failure Records conditions and the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 4

Go to Diagnostic Aids

4
  1. Turn off the engine, leaving the ignition on.
  2. Disconnect the camshaft position (CMP) sensor connector.
  3. Connect a test lamp to ground.
  4. Probe the ignition positive voltage circuit at the CMP sensor connector.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 6

5
  1. Connect a test lamp to B+.
  2. Probe the CMP ground circuit at the connector.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 8

6
  1. Turn off the ignition.
  2. Test the CMP ignition positive voltage circuit for the following conditions:
    3. • A poor connection
    • An open
    • A short to ground
  3. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

7
  1. Turn off the ignition.
  2. Install fused jumpers between the CMP connector and the CMP sensor on the following circuit:
    3. • The round
    • The sensor ignition positive voltage
  3. Remove the fuel pump fuse.

    4. Important:: The DMM must be connected to Sensor ground to insure proper readings.

  4. Connect a DMM to Sensor ground.
  5. Set the DMM on Hz.
  6. Probe the CMP signal circuit at the CMP sensor.
  7. Crank the engine.

Does the frequency vary within the specified range?

0.5-2.6 Hz

Go to Step 9

Go to Step 14

8
  1. Turn off the ignition.
  2. Inspect the CMP ground circuit for the following conditions:
    3. • A poor connection
    • An open
  3. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

9
  1. Turn off the ignition.
  2. Disconnect the PCM connector C1.
  3. Remove all the fused jumpers.
  4. Turn on the ignition, leaving the engine off.
  5. Connect a test lamp to ground.
  6. Probe the CMP sensor signal circuit at the CMP connector.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 10

10
  1. Connect a test lamp to B+.
  2. Probe the CMP sensor signal circuit at the CMP connector.

Does the test lamp illuminate?

--

Go to Step 13

Go to Step 11

11
  1. Turn off the ignition.
  2. Inspect the CMP sensor signal circuit for the following conditions:
    3. • An open
    • A poor connection
  3. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

12
  1. Turn off the ignition.
  2. Repair the short to B+ in the CMP signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

13
  1. Turn off the ignition.
  2. Repair the short to ground in the CMP signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

14
  1. Turn off the ignition.
  2. Inspect the CMP sensor for a poor connection.
  3. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition.

--

Go to Step 18

Go to Step 16

15
  1. Turn off the ignition.
  2. Inspect the PCM for poor connections. If a problem is found, repair as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and complete the repair?

--

Go to Step 18

Go to Step 17

16

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

Did you complete the repair?

--

Go to Step 18

--

17

Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the repair?

--

Go to Step 18

--

18
  1. Use a scan tool to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK