DTC P0340 CMP Sensor Circuit Low Input. Pontiac Sunfire 2000

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2000 🢒 Sunfire 🢒 DTC 🢒 DTC P0340 CMP Sensor Circuit Low Input

Engine Controls Component Views
Power, Ground, CMP, KS, and CKP
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, then 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 by 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 two 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 three 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 faulty electrical connection

-	Rubbed-through wire insulation

-	Broken wire inside the insulation

•	Thoroughly check any suspected circuitry for the following conditions:

-	Backed-out terminals

-	Improper mating

-	Broken locks

-	Improperly formed connectors

-	Damaged terminals

-	Faulty terminal-to-wire connections

-	Physical damage to the wiring harness

Test Description

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

The Powertrain On-Board Diagnostic (OBD) System Check prompts you to complete some of the basic diagnostics and to store the Freeze Frame and Failure Records data on the scan tool, if applicable. This creates an electronic copy of the data that was captured when the malfunction occurred. The scan tool stores this data for later reference.

This step determines if the DTC P0340 is the result of a hard malfunction or an intermittent condition.

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

This step checks for a signal from the CMP sensor. It is necessary to supply B+ to the CMP sensor ignition positive voltage terminal in order for the CMP sensor to have B+ supplied to the CMP sensor. While cranking the engine, the CMP sensor will send a varying voltage signal that can be read by the DMM as a frequency check.

Reprogram the replacement PCM and perform the crankshaft position system variation learning procedure. Refer to the latest Techline™ procedures for PCM reprogramming.

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

Step

Action

Value(s)

Yes

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

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Install a scan tool.
Start the engine.
Idle the engine.
Observe the CMP active counter with the scan tool.

Is the CMP Active counter incrementing?

Go to Step 3

Go to Step 4

Turn ON the ignition, with the engine OFF.
Review the Freeze Frame data and record the parameters.
Start the engine.
Operate the vehicle within the Freeze Frame conditions and Conditions for Setting the DTC as specified.

Is the CMP active counter incrementing?

Go to Step 16

Go to Step 4

Turn ON the ignition, with the engine OFF.
Remove the air cleaner outlet resonator. Refer to Air Cleaner Outlet Resonator Replacement .
Disconnect the camshaft position (CMP) sensor electrical connector.
Connect a test lamp to a ground.
Probe the battery positive voltage terminal of the CMP electrical connector.

Did the test lamp illuminate?

Go to Step 5

Go to Step 6

Connect a test lamp to B+.
Probe the CMP electrical connector ground terminal.

Did the test lamp illuminate?

Go to Step 7

Go to Step 8

Check for the following conditions on the CMP battery positive voltage circuit:

•	A faulty electrical connection

•	An open connection

•	A short to ground

Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

Go to Step 16

Go to Step 15

Turn OFF the ignition.
Use the correct test adapters from the J 35616 and install adapters to the CMP connector terminals A and B.
Install the correct adapters to the CMP sensor terminals A and B.
Connect the fused jumper wires between each of the adapters to the correct corresponding terminals on the CMP sensor.
Remove the fuel pump fuse.
Connect a DMM to a ground.
Select the A/C volt scale on the DMM, then select the Hz scale.
Probe the CMP signal terminal C of the CMP sensor.
Crank the engine and observe the DMM.

Does the DMM display a frequency reading that is varying between the specified values?

0.5-2.6 Hz

Go to Step 9

Go to Step 14

Check for the following conditions on the CMP ground circuit:

•	A faulty electrical connection

•	An open connection

Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

Go to Step 16

Go to Step 15

Turn OFF the ignition.
Disconnect the PCM electrical connector C1.
Remove all the fused jumper wires and test adapters from the CMP sensor and the CMP sensor electrical connector.
Turn ON the ignition, with the engine OFF.
Connect a test lamp to a ground.
Probe the CMP sensor signal terminal at the CMP electrical connector with the test lamp.

Does the test lamp illuminate?

Go to Step 12

Go to Step 10

Connect a test lamp to B+.
Probe the CMP sensor signal harness connection terminal C with the test lamp.

Does the test lamp illuminate?

Go to Step 13

Go to Step 11

Check the CMP sensor signal circuit for the following conditions:

•	An open circuit

•	A faulty electrical terminal connection at the CMP sensor

Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

Go to Step 16

Go to Step 15

Turn OFF the ignition.
Repair the short to B+ in the CMP signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

Go to Step 16

Turn OFF the ignition.
Repair the short to ground in the CMP signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

Go to Step 16

Turn OFF the ignition.
Check for a faulty electrical connection at the CMP sensor electrical connector. Refer to Wiring Repairs in Wiring Systems.
If the CMP electrical connection is OK, replace the CMP sensor. Refer to Camshaft Position Sensor Replacement .

Is the action complete?

Go to Step 16

Turn OFF the ignition.
Check for a faulty electrical terminal connection at the PCM electrical connector.
Refer to Powertrain Control Module Replacement/Programming .
If the connection is OK, replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 16

Install the fuel pump fuse if the pump is still removed.
Reconnect the CMP electrical connector if the electrical connector is still disconnected.
Clear the DTCs with the scan tool.
Start the engine.
Idle the engine at the normal operating temperature.
Operate the vehicle within the Conditions for Running this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has run and passed?

Go to Step 17

Go to Step 2

Check to see if any additional DTCs are set.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List/Type

System OK