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Circuit Description
The Camshaft Position (CMP) 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 sensor's internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position (CKP) sensor 24X signal in order to determine crankshaft position and stroke. The PCM monitors for a loss of the CMP sensor signal.
Observe that as long as the PCM receives the Crankshaft Position sensor 24X signal, the engine will start. The PCM can determine top dead center for all cylinders by using the Crankshaft Position sensor 24X signal alone. The Camshaft Position sensor 1X signal is used by the PCM to determine if the cylinder at top dead center is on the firing stroke, or the exhaust stroke. The system attempts synchronization and looks for an increase in engine speed indicating the engine started. If the PCM does not detect an increase in engine speed, 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
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 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 the MIL OFF after three consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed (current DTC) clears when the diagnostic runs and does not fail.
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
Use a scan tool in order to clear the MIL/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.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A. Using this kit prevents damage to the harness/component terminals.
The following conditions may cause this DTC to set:
Poor connections.
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.
For an intermittent, refer to Symptoms. See: Diagnosis By Symptom (Computers and Control Systems)
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 tests the Camshaft Position sensor B+ reference circuit.
This step tests the Camshaft Position sensor ground circuit.
This step tests for a short to B+ on the Camshaft Position sensor signal circuit.
This step tests for a short to ground on the Camshaft Position sensor signal circuit.
I have a 2005 Tahoe 5.3L and got a P0342 code. The battery is only 2 weeks old so I changed the Camshaft Position Sensor but I still get the P0342 code. I also noticed that when I start the Tahoe I have to make second attempt for it to start, that never happened before. Can anyone help me to resolve this issue. Thanks.
I am having the same issue with my 2005 Suburban 5.3L. I replaced my camshaft sensor as well and same code. What ended up fixing yours?
A "circuit low" is sometimes a wiring issue...short to ground ...if you didn't check wiring you only did half the job...these CMP sensors are the same as the C5...3 wire Hall Effect sensors...a 12 volt reference from the PCM, a signal wire (pull up or pull down circuit design) back to the PCM, and sensor ground !!...I don't have a wiring diagram so I can't help you there !!
Ok, Found that the CMP sensor is located in top rear of engine near flywheel...PCM located between battery and radiator. Your 12 volt ref. is the red wire...the "low reference" (ground) is pink/black. The signal wire is brown/white. With sensor harness
still connected back probe (pictured) the red wire and with key ON you should have 12 volts. The ground should be LESS THAN 100mv (.1 volts) and signal wire should read low like .02V or .03V if it is a "pull up" or will read 12 volts if it is a "pull down"...if voltage read low with your voltmeter STILL CONNECTED to the brown/white take a 12 volt test light connected to battery POSITIVE...touch the tip of test light to the volt meter red lead that is connected to the signal wire...the voltmeter should read 12 volts if signal wire good...if signal wire reads 12 volts switch test light to battery NEGATIVE and touch tip to brown/white...volt meter should now read low if signal wire good !!
I was getting zero voltage read from the cmp connector pin that leads to the brw/wht wire but when I inserted a t pin through the cable i was getting proper voltage. Replaced the connector and issue is resolved. Thanks for your help!
Originally Posted by C5 Diag
Ok, Found that the CMP sensor is located in top rear of engine near flywheel...PCM located between battery and radiator. Your 12 volt ref. is the red wire...the "low reference" (ground) is pink/black. The signal wire is brown/white. With sensor harness
still connected back probe (pictured) the red wire and with key ON you should have 12 volts. The ground should be LESS THAN 100mv (.1 volts) and signal wire should read low like .02V or .03V if it is a "pull up" or will read 12 volts if it is a "pull down"...if voltage read low with your voltmeter STILL CONNECTED to the brown/white take a 12 volt test light connected to battery POSITIVE...touch the tip of test light to the volt meter red lead that is connected to the signal wire...the voltmeter should read 12 volts if signal wire good...if signal wire reads 12 volts switch test light to battery NEGATIVE and touch tip to brown/white...volt meter should now read low if signal wire good !!
09-14-2006, 09:42 AM
