DTC P0340 Camshaft Position (CMP) Sensor Circuit. Geo Prizm 1996

For 1990-2009 cars

Schematic Reference: Engine Controls Schematics

### Circuit Description

The camshaft position (CMP) sensor is a magnetic generator type sensor, producing an alternating current signal which increases in both frequency and amplitude as the engine RPM increases. The camshaft position signal along with the crankshaft position sensor signal are used by the PCM to determine crankshaft speed, crankshaft position and piston stroke. This information is used by the PCM to calculate fuel injection pulse, establish top dead center for ignition timing and where to start ignition coil and injection sequencing.

### Conditions for Setting the DTC

· No camshaft position sensor signal to PCM during cranking.

OR

· No camshaft position sensor signal to PCM with engine speed at 600 RPM or greater.

### Action Taken When the DTC Sets

• | The PCM will illuminate the MIL during the second key cycle in which the DTC sets.

• | The PCM will store the conditions which were present when the DTC set as Freeze Frame Data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn the MIL "OFF" on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.

• | A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.

• | A DTC can be cleared by using the scan tool "Clear Information" function or by disconnecting the PCM battery feed.

### Diagnostic Aids

• | Check that signal rotor air gap is adjusted properly.

• | An intermittent malfunction may be cause by a poor connection, rubbed through wire insulation, or a broken wire inside the insulation. Inspect harness connectors for backed out terminals, improper matting, broken locks, terminal-to wire connection before component replacement

• | The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.

### Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

1. The OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. This step checks whether DTC P0340 is the result of a hard failure or an intermittent condition. If engine will not start, crank engine over (3 consecutive ignition cycles).

3. Checking the internal resistance of the camshaft position sensor verifies if the CMP sensor is operating properly

4. Both the camshaft position input and crank angle ground circuits need to be check. Using a DVM, measure resistance of the wires from PCM connector to CMP connector (PCM side), if the DVM reads higher than 0.5 ohms check for a short or high resistance in the circuit. Also using a test light connected to ground with both PCM and CMP connectors unplugged, probe each connector terminal, will check whether there is a short to battery voltage.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the "Powertrain On Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain Control Module Connector End Views

2

1. Clear the DTC.
2. Using the scan tool, place the vehicle into Check Mode.
3. Operate vehicle within Condition for Setting the DTC, (if the car will not start, crank engine over).

Does DTC P0340 set?

--

Go to Step 3

Go to Diagnostic Aids

3

1. Turn the ignition switch OFF.
2. Disconnect the distributor connector.
3. Using a DMM measure the resistance of the CMP sensor.

Does the DMM read within the specified value?

185-275 ohms at 50°C (122°F) or 240-325 ohms at 100°C (212°F)

Go to Step 4

Go to Step 6

4

1. Disconnect the PCM harness connector.
2. Check for an open or short in the CMP circuit.
3. Repair as necessary.

Was a repair necessary?

--

Go to Step 8

Go to Step 5

5

1. Check for a poor connection at the PCM and the distributor connector.
2. Repair terminals as necessary.

Was a repair necessary?

--

Go to Step 8

Go to Step 7

6 | Replace the Distributor Housing. Is the action complete? | -- | Go to Step 8 | --
7 | Replace the PCM. Is the action complete? | -- | Go to Step 8 | --
8 | After repairs, use the scan tool clear information function and road test vehicle within "Freeze Frame" conditions that set the DTC. Check for DTC(s) Current or History. Review scan tool data and if no DTC(s) are stored repair is complete. Are any DTC(s) displayed on scan tool? | -- | Go to Applicable DTC table | System OK