Mechanics

CHEVROLET SILVERADO SENSOR PROBLEM

2001 Chevrolet Silverado • 75,000 miles

Have a 2500hd with an 8.1. Giving code p0342 low input on the camshaft sensor.I have already replaced the sensor and connector and put a new battery in the vehicle. I will check the starter shortly. Any other ideas?
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Kylemeyer
March 20, 2013.



Here is the check chart for the code

CIRCUIT DESCRIPTION
The Camshaft Position (CMP) sensor works in conjunction with a 1X reluctor wheel on the camshaft. The Powertrain Control Module (PCM) provides a 12-volt reference circuit to the CMP sensor as well as a low reference 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 CKP sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic for the CMP sensor checks for a loss of CMP sensor signal.

Observe that as long as the PCM receives the CKP sensor 24X signal, the engine will start. The PCM can determine top dead center for all cylinders by using the CKP sensor 24X signal alone. The CMP sensor 1X signal is used by the PCM in order to determine if the cylinder at Top Dead Center (TDC) is on the firing stroke or on 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
The engine speed is less than 4,000 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 control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
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
The following conditions may cause this DTC to set: Camshaft reluctor wheel damage
The sensor coming in contact with the reluctor wheel
Foreign material passing between the sensor and the reluctor wheel
Using Freeze Frame/Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/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 or a fail. Operate the vehicle within the same Freeze Frame conditions such as RPM, load, vehicle speed, temperature, etc. That you observed. This will isolate when the DTC failed.

The CMP sensor output can be tested. The sensor must be supplied with a power and a ground. The engine must be cranking to perform this test. You can measure the duty cycle at the signal circuit of the sensor. The duty cycle should be between 45-55 percent for a good sensor.

If the problem is intermittent, Refer to Intermittent Conditions. See: Powertrain Management\Computers and Control Systems\Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic Strategies\Intermittent Conditions

Roy

ASEMaster6371
Mar 20, 2013.
Sorry should have also said that we have cleared the code several times and it keeps returning

Tiny
Kylemeyer
Mar 20, 2013.
Clearing does nothing. The light is on for the issue and clearing does nothing. You need to repair the problem, then the light will go out and stay out

Roy

ASEMaster6371
Mar 20, 2013.
Ok thanks for the info. I am very much an amateur mechanic Am I in over my head? Or can the info you've given be taken care of in my garage?

Tiny
Kylemeyer
Mar 20, 2013.
Take your time and follow each line. Try not to skip any steps along the way.

Roy

ASEMaster6371
Mar 20, 2013.