camshaft position sensor question
Thread Starter
Burning Brakes
Joined: Oct 2007
Posts: 1,093
Likes: 33
From: Morristown TN
camshaft position sensor question
I need a little info on the camshaft sensor.
I have been getting a code P0342 for a long time, well over a year, I did have a new sensor installed but that did not help.
I was told that the only problem I would have would be extra time starting it because the computer would use the Crank position sensor as a backup and the car would run fine even if the sensor was not hooked up at all.
I am now trying to track down a slight engine miss at normal highway speed along with loss of MPG It dropped from 30mpg average on a long drive to about 20MPG
When the engine is running hard it is great and has all the power it ever had.
The 0342 is the only code other than p1571 desired torque which has been on it for 5 years
Could the cam sensor cause this/. Is there a way to test the sensor.
thanks in advance.
I have been getting a code P0342 for a long time, well over a year, I did have a new sensor installed but that did not help.
I was told that the only problem I would have would be extra time starting it because the computer would use the Crank position sensor as a backup and the car would run fine even if the sensor was not hooked up at all.
I am now trying to track down a slight engine miss at normal highway speed along with loss of MPG It dropped from 30mpg average on a long drive to about 20MPG
When the engine is running hard it is great and has all the power it ever had.
The 0342 is the only code other than p1571 desired torque which has been on it for 5 years
Could the cam sensor cause this/. Is there a way to test the sensor.
thanks in advance.
Melting Slicks
Joined: Nov 1999
Posts: 2,347
Likes: 857
From: MI
Cruise-In VI Veteran
for 1998
C P0342 Camshaft Position (CMP) Sensor Circuit Low Voltage
Circuit Description
The Camshaft Position sensor is mounted through the top of the engine block at the rear of the valley cover. The CMP sensor works in conjunction with a 1X reluctor wheel on the camshaft. The reluctor wheel is inside the engine immediately in front of the rear cam bearing. The PCM provides a 12 volt power supply to the CMP sensor as well as a ground and a signal circuit.
The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic for the Camshaft Position sensor checks for a loss of Camshaft Position sensor signal.
Observe that as long as the 24X signal is available, the engine starts even if there is no Camshaft Position sensor signal. The PCM can determine when a particular cylinder is on either a firing or exhaust stroke by the 24X signal alone, but the PCM requires the cam signal in order to determine which (firing or exhaust). The system attempts synchronization and looks for an increase in engine speed indicating the engine started. If the PCM does not detect an engine speed increase, the PCM assumes it incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.
Conditions for Running the DTC
• System voltage is between 9.0 volts and 17.0 volts.
• Engine speed is less than 4000 RPM.
Conditions for Setting the DTC
The PCM detects the Cam signal is stuck low when the signal should be high for 1.5 seconds.
Action Taken When the DTC Sets
• The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
• The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
Important: Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
The following mechanical problems may cause this DTC to set:
• Poor connections/terminal tension at the sensor
• Camshaft reluctor wheel damage
• The sensor coming in contact with the reluctor wheel
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step verifies that the fault is present.
If the duty cycle is present at the PCM connector, the Camshaft Position sensor B+ reference and ground circuits are OK.
This step checks the Camshaft Position sensor B+ reference circuit.
This step checks the Camshaft Position sensor ground circuit.
This step checks for a short to B+ on the Camshaft Position sensor signal circuit.
This step checks for a short to ground on the Camshaft Position sensor signal circuit.
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
Install a scan tool.
Idle the engine.
Monitor the CAM signal input - High to Low transition in the Engine Data List 1 using the scan tool.
Does the scan tool parameter increment?
--
Go to Step 3
Go to Step 4
3
Turn ON the ignition leaving the engine OFF.
Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
Turn OFF the ignition for 15 seconds.
Idle the engine.
Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Setting the DTC.
Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, then enter the DTC number using the scan tool.
Does the scan tool indicate that this diagnostic failed this ignition?
--
Go to Step 4
Go to Diagnostic Aids
4
Disconnect the PCM connector located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .
Install the brown terminal from the terminal kit J 35616 into the Camshaft Position sensor signal circuit (PCM harness side).
Probe the Camshaft Position sensor signal circuit with one lead of the DMM and connect the other lead to a ground.
Select the duty cycle option on the DMM.
Crank the engine.
Does the DMM display a duty cycle within the specified range?
45% - 55%
Go to Step 17
Go to Step 5
5
Turn OFF the ignition.
Reconnect the PCM connector.
Remove the intake manifold in order to gain access to the Camshaft Position sensor. Refer to Engine/Engine Mechanical for the procedure.
Disconnect the Camshaft Position sensor electrical connector.
Turn ON the ignition leaving the engine OFF.
Measure the voltage from the Camshaft Position sensor B+ reference circuit to the battery ground using the DMM J 39200 .
Does the DMM display the specified voltage?
B+
Go to Step 6
Go to Step 8
6
Measure the voltage from the Camshaft Position sensor B+ reference circuit to the Camshaft Position sensor ground circuit using the DMM J 39200 .
Does the DMM display the specified voltage?
B+
Go to Step 9
Go to Step 7
7
Check for an open in the Camshaft Position sensor ground circuit.
If you find a circuit problem, repair the circuit as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 20
Go to Step 17
8
Check for an open or a short to ground in the Camshaft Position sensor B+ reference circuit.
If you find a circuit problem, repair the circuit as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 20
Go to Step 17
9
Turn ON the ignition leaving the engine OFF.
Measure the voltage at the Camshaft Position sensor signal circuit to ground using the DMM J 39200 .
Is the voltage less than the specified value?
1.0V
Go to Step 10
Go to Step 14
10
Probe the Camshaft Position sensor signal circuit using the Test Lamp connected to battery positive voltage.
Does the Test Lamp illuminate?
--
Go to Step 15
Go to Step 11
11
Turn OFF the ignition.
Disconnect the PCM connector located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .
Check the continuity of the signal circuit from the sensor harness connector to the PCM using the DMM J 39200 .
Is the resistance less than the value specified?
5ohms
Go to Step 18
Go to Step 16
12
Repair the open or short to ground in the Camshaft Position sensor B+ reference circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
13
Repair the open in the Camshaft Position sensor ground circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
14
Repair the short to voltage in the Camshaft Position sensor signal circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
15
Repair the short to ground in the Camshaft Position sensor signal circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
16
Repair the open in the Camshaft Position sensor signal circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
17
Check the connections at the PCM. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 20
Go to Step 19
18
Important: Before replacing the CMP sensor, inspect the harness connector for proper terminal tension. Refer to Body and Accessories/Wiring Systems.
Replace the Camshaft Position sensor. Refer to Camshaft Position Sensor Replacement .
Is the action complete?
--
Go to Step 20
--
19
Important : Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .
Replace the PCM.
Is the action complete?
--
Go to Step 20
--
20
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test ran and passed?
--
Go to Step 21
Go to Step 2
21
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to applicable DTC Table
System OK
C P0342 Camshaft Position (CMP) Sensor Circuit Low Voltage
Circuit Description
The Camshaft Position sensor is mounted through the top of the engine block at the rear of the valley cover. The CMP sensor works in conjunction with a 1X reluctor wheel on the camshaft. The reluctor wheel is inside the engine immediately in front of the rear cam bearing. The PCM provides a 12 volt power supply to the CMP sensor as well as a ground and a signal circuit.
The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic for the Camshaft Position sensor checks for a loss of Camshaft Position sensor signal.
Observe that as long as the 24X signal is available, the engine starts even if there is no Camshaft Position sensor signal. The PCM can determine when a particular cylinder is on either a firing or exhaust stroke by the 24X signal alone, but the PCM requires the cam signal in order to determine which (firing or exhaust). The system attempts synchronization and looks for an increase in engine speed indicating the engine started. If the PCM does not detect an engine speed increase, the PCM assumes it incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.
Conditions for Running the DTC
• System voltage is between 9.0 volts and 17.0 volts.
• Engine speed is less than 4000 RPM.
Conditions for Setting the DTC
The PCM detects the Cam signal is stuck low when the signal should be high for 1.5 seconds.
Action Taken When the DTC Sets
• The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
• The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
Important: Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
The following mechanical problems may cause this DTC to set:
• Poor connections/terminal tension at the sensor
• Camshaft reluctor wheel damage
• The sensor coming in contact with the reluctor wheel
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step verifies that the fault is present.
If the duty cycle is present at the PCM connector, the Camshaft Position sensor B+ reference and ground circuits are OK.
This step checks the Camshaft Position sensor B+ reference circuit.
This step checks the Camshaft Position sensor ground circuit.
This step checks for a short to B+ on the Camshaft Position sensor signal circuit.
This step checks for a short to ground on the Camshaft Position sensor signal circuit.
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
Install a scan tool.
Idle the engine.
Monitor the CAM signal input - High to Low transition in the Engine Data List 1 using the scan tool.
Does the scan tool parameter increment?
--
Go to Step 3
Go to Step 4
3
Turn ON the ignition leaving the engine OFF.
Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
Turn OFF the ignition for 15 seconds.
Idle the engine.
Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Setting the DTC.
Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, then enter the DTC number using the scan tool.
Does the scan tool indicate that this diagnostic failed this ignition?
--
Go to Step 4
Go to Diagnostic Aids
4
Disconnect the PCM connector located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .
Install the brown terminal from the terminal kit J 35616 into the Camshaft Position sensor signal circuit (PCM harness side).
Probe the Camshaft Position sensor signal circuit with one lead of the DMM and connect the other lead to a ground.
Select the duty cycle option on the DMM.
Crank the engine.
Does the DMM display a duty cycle within the specified range?
45% - 55%
Go to Step 17
Go to Step 5
5
Turn OFF the ignition.
Reconnect the PCM connector.
Remove the intake manifold in order to gain access to the Camshaft Position sensor. Refer to Engine/Engine Mechanical for the procedure.
Disconnect the Camshaft Position sensor electrical connector.
Turn ON the ignition leaving the engine OFF.
Measure the voltage from the Camshaft Position sensor B+ reference circuit to the battery ground using the DMM J 39200 .
Does the DMM display the specified voltage?
B+
Go to Step 6
Go to Step 8
6
Measure the voltage from the Camshaft Position sensor B+ reference circuit to the Camshaft Position sensor ground circuit using the DMM J 39200 .
Does the DMM display the specified voltage?
B+
Go to Step 9
Go to Step 7
7
Check for an open in the Camshaft Position sensor ground circuit.
If you find a circuit problem, repair the circuit as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 20
Go to Step 17
8
Check for an open or a short to ground in the Camshaft Position sensor B+ reference circuit.
If you find a circuit problem, repair the circuit as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 20
Go to Step 17
9
Turn ON the ignition leaving the engine OFF.
Measure the voltage at the Camshaft Position sensor signal circuit to ground using the DMM J 39200 .
Is the voltage less than the specified value?
1.0V
Go to Step 10
Go to Step 14
10
Probe the Camshaft Position sensor signal circuit using the Test Lamp connected to battery positive voltage.
Does the Test Lamp illuminate?
--
Go to Step 15
Go to Step 11
11
Turn OFF the ignition.
Disconnect the PCM connector located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .
Check the continuity of the signal circuit from the sensor harness connector to the PCM using the DMM J 39200 .
Is the resistance less than the value specified?
5ohms
Go to Step 18
Go to Step 16
12
Repair the open or short to ground in the Camshaft Position sensor B+ reference circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
13
Repair the open in the Camshaft Position sensor ground circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
14
Repair the short to voltage in the Camshaft Position sensor signal circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
15
Repair the short to ground in the Camshaft Position sensor signal circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
16
Repair the open in the Camshaft Position sensor signal circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 20
--
17
Check the connections at the PCM. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 20
Go to Step 19
18
Important: Before replacing the CMP sensor, inspect the harness connector for proper terminal tension. Refer to Body and Accessories/Wiring Systems.
Replace the Camshaft Position sensor. Refer to Camshaft Position Sensor Replacement .
Is the action complete?
--
Go to Step 20
--
19
Important : Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .
Replace the PCM.
Is the action complete?
--
Go to Step 20
--
20
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test ran and passed?
--
Go to Step 21
Go to Step 2
21
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to applicable DTC Table
System OK
