HAVE A 2500HD WITH AN 8

  • Tiny
  • kylemeyer
  • 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?

Wednesday, March 20th, 2013 AT 9:48 PM

6 Answers

  • Tiny
  • ASEMaster6371
  • Expert
  • 25,555 posts

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

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Wednesday, March 20th, 2013 AT 10:21 PM
  • Tiny
  • kylemeyer
  • Member

Sorry should have also said that we have cleared the code several times and it keeps returning

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Wednesday, March 20th, 2013 AT 10:56 PM
  • Tiny
  • ASEMaster6371
  • Expert
  • 25,555 posts

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

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Wednesday, March 20th, 2013 AT 11:01 PM
  • Tiny
  • kylemeyer
  • Member

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?

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Wednesday, March 20th, 2013 AT 11:10 PM
  • Tiny
  • ASEMaster6371
  • Expert
  • 25,555 posts

Take your time and follow each line. Try not to skip any steps along the way.

Roy

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Wednesday, March 20th, 2013 AT 11:11 PM
  • Tiny
  • Twitch2500HD8.1
  • Member

I know this is years late but if anybody is having the same issue with a 2500HD 8.1 and sees this, I will share my fix. I have a 2003 Sierra 2500HD 8.1 gasoline. I got the P0342 code a couple years ago, replaced the cam sensor, replaced the crankshaft sensor, had the wiring harness checked, replaced PCM and the code would always come back soon after the engine started. The engine had a hard start/long cranking and backfiring. Once the engine started it ran just fine though. GM has stopped making certain parts for 2003 and the timing system is one of them so even finding the new cam sensor and harness was a pain. I ended up converting my timing system to the 2004+ setup. Everything is the same fit for the 2003. You will need a timing gear set for a 2004 (The new cam gear has a different design for the new sensor), timing cover for 2004(the new timing cover has a raised section to allow room for the taller sensor), camshaft positioning sensor for 2004(taller sensor), wiring harness pigtail for 2004 camshaft positioning sensor(to cut and splice with existing harness wires). I bought a new water pump since I was removing the old one to remove the timing cover and installed that as well. Truck fires right up like brand new everytime and code has been gone since. I spent about 500 on parts. The only thing I had to purchase from dealer was the timing cover which came with gasket and oil seal installed. Everything else was an OEM part from an auto parts store in my area. You will need a special harmonic damper puller as the standard 3 bolt puller will not work. You need the Lisle puller, part number 51450. Lisle also makes the damper installer tool as well. I used the rental from AutoZone which is not ideal on this truck as the Driving Nut is recessed because the Damper is not flat faced. Took me an hour and a half and a lot of sweat and knuckle busting to install mine back on where I' m sure the lisle installer would have made the job much easier. I also baked my crankshaft timing gear in the oven at 350 degrees for 15-20 minutes right before installing it. This will make the gear expand and slip back over the crank all the way without having to be pressed on. Line up the keyway and slide the gear on, leave it alone for 30 minutes, let the gear cool down and it will shrink and pressure fit itself. Hope this helps someone

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Friday, April 29th, 2016 AT 10:15 PM

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