LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Pontiac >> 2005 >> Grand Prix Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 3.8L - DTC P0137 To DTC P0405 >> DTC P0340 >> Test Description
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Test Description

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

  1. 14:  This test verifies if the sensor is working correctly. By suppling a ground to the circuit, the voltage should change when the circuit is touched with a test lamp.
  2. 26:  This step determines if the fault is caused by a missing camshaft magnet or by a faulty PCM. The voltage measured in this step should be near 5 volts, and decrease to near 0 volts when the CMP sensor interfaces with the camshaft magnet.
DTC P0340

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) 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 Attempt to start the engine.
Does the engine start and run?		 - Go to Step 3  Go to Step 4 
3
  1. Turn OFF the ignition for 30 seconds.
  2. Start the engine.
  3. 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 4  Go to Diagnostic Aids
4
  1. Turn OFF the ignition.
  2. Disconnect the powertrain control module (PCM).
  3. Turn ON the ignition, with the engine OFF.
    4. IMPORTANT: If voltage measures 0 volts, rotate the crankshaft to ensure the camshaft position (CMP) sensor magnet is not located under the CMP sensor at the time of the test.
  4. Measure the voltage from the CMP signal circuit at the PCM connector to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage within the specified range?		 4.5-5.5 V Go to Step 8  Go to Step 5 
5 Does the voltage on the CMP signal circuit measure more than the specified value? 5 V Go to Step 17  Go to Step 6 
6 Probe the CMP signal circuit at the PCM connector with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 16  Go to Step 7 
7
  1. Disconnect the ignition control module (ICM).
  2. Measure the resistance of the CMP signal circuit between the ICM and the PCM with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance within the specified value?		 0-5 Ω Go to Step 8  Go to Step 15 
8
  1. Turn OFF the ignition.
  2. Remove the CMP sensor from the engine front cover without disconnecting the CMP sensor harness connector. Refer to Camshaft Position (CMP) Sensor Replacement .
    3. IMPORTANT: The magnet used must have sufficient power and the correct polarity. If the voltage remains at 5 volts, retest using the opposite end of the magnet.
  3. Turn ON the ignition, with the engine OFF.
  4. Place a magnet on the CMP sensor.
  5. Measure the voltage from the CMP signal circuit at the PCM connector to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Does the voltage toggle from 5 volts to 0 volts when the magnet is moved across the sensor surface?		 - Go to Step 25  Go to Step 9 
9
  1. Turn OFF the ignition.
  2. Install the CMP sensor to the engine front cover.
  3. Disconnect the CMP sensor.
  4. Turn ON the ignition, with the engine OFF.
  5. Probe the 12-volt reference circuit of the CMP sensor with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 10  Go to Step 18 
10
  1. Turn OFF the ignition
  2. Disconnect the ICM.
  3. Measure the resistance of the low reference circuit from the CMP sensor connector to the ICM connector with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance within the specified value?		 0-5 Ω Go to Step 11  Go to Step 19 
11
  1. Connect the ICM.
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the voltage from the CMP sensor signal circuit of the CMP sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage less than the specified value?		 7 V Go to Step 12  Go to Step 22 
12
  1. Turn OFF the ignition.
  2. Disconnect the ICM.
  3. Measure the resistance of the CMP sensor signal circuit from the CMP sensor connector to the ICM connector with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance within the specified range?		 0-5 Ω Go to Step 13  Go to Step 20 
13
  1. Connect the ICM.
  2. Turn ON the ignition, with the engine OFF.
  3. Probe the CMP sensor signal circuit of the CMP sensor with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 21  Go to Step 14 
14 
  1. Connect the ICM.
  2. Disconnect the PCM.
  3. Turn ON the ignition, with the engine OFF.
  4. Momentarily and repeatedly probe the CMP sensor signal circuit with a test lamp that is connected to a good ground.
  5. Measure the voltage on the CMP signal circuit at the PCM connector to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Does the voltage change when the circuit is touched?		 - Go to Step 24  Go to Step 23 
15 Repair the open in the CMP signal circuit between the ICM and the PCM. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 31  -
16 Test the CMP signal circuit between the ICM and the PCM for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 31  Go to Step 23 
17 Test the CMP signal circuit between the ICM and the PCM for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 31  Go to Step 23 
18 Test the CMP 12-volt reference circuit between the CMP sensor and the ICM for an open, high resistance, or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 31  Go to Step 23 
19 Repair the open or high resistance in the low reference circuit between the CMP sensor and the ICM. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 31  -
20 Repair the open or high resistance in the CMP sensor signal circuit between the CMP sensor and the ICM. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 31  -
21 Test the CMP sensor signal circuit between the CMP sensor and the ICM for a short to ground. Refer to Circuit Testing andWiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 31  Go to Step 23 
22 Test the CMP sensor signal circuit between the CMP sensor and the ICM for a short to voltage. Refer to Circuit Testing andWiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 31  Go to Step 23 
23 Test for an intermittent and for a poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections andConnector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 31  Go to Step 27 
24 Test for an intermittent and for a poor connection at the 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 31  Go to Step 28 
25 Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections andConnector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 31  Go to Step 26 
26 
  1. Install the CMP sensor to the engine front cover. Refer to Camshaft Position (CMP) Sensor Replacement .
  2. Measure the voltage of the CMP signal circuit at the PCM connector to ground with a DMM. Refer to Circuit Testing in Wiring Systems.
  3. Observe the voltage while repeatedly bumping the engine with the starter.
Does the voltage toggle from 5 volts to 0 volts while bumping the engine with the starter?		 - Go to Step 29  Go to Step 30 
27 Replace the ICM. Refer to Ignition Control Module Replacement .
Did you complete the replacement?		 - Go to Step 31  -
28 Replace the CMP sensor. Refer to Camshaft Position (CMP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 31  -
29 Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 31  -
30 Replace a faulty or missing CMP sensor magnet on the camshaft sprocket.
Did you complete the replacement?		 - Go to Step 31  -
31
  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 32 
32 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
scientia non olet · About LEMON Manuals