Camshaft sensor - inductive

The purpose of this test is to evaluate the correct operation of an inductive Camshaft Position (CMP) sensor based on the output voltage and frequency with the engine at idle speed.

Connection guidance

Connection for diagnostic work will vary dependent on application.

Technicians should whenever possible gain access to the test circuit without damage to seals and insulation. If this is not possible then make sure appropriate repairs are completed.

General connection advice

PicoScope offer a range of options within the test kits.

Dependent on difficulty of access, choose from:

  1. Breakout leads.
  2. Back-pinning probes.

Testing sensors and actuators (in order to include the relevant harness and connectors):

  • When testing a sensor, it is desirable to gain access at the control module.
  • When testing an actuator, it is desirable to gain access at the actuator.

How to perform the test

  1. Use the vehicle wiring diagram to identify the signal circuit.
  2. Connect PicoScope Channel A.
  3. Start the engine and run at idle.
  4. Minimise the help page and with the example waveform on your screen PicoScope has already selected suitable scales for you to capture a waveform.
  5. Select Go or press the space bar to see live data.
  6. With your live waveform on screen select Stop or press the space bar to stop your capture.
  7. Use the Waveform Buffer and Zoom tools to examine your waveform.

Example waveform

Waveform notes

This known good waveform has the following characteristics:

A periodic waveform, similar to a single sine wave cycle, occurring once every 720 degrees of crankshaft rotation (i.e. once per 360 degrees of camshaft rotation).

As engine speed increases, amplitude and frequency increase.

There is no excessive noise nor any inconsistent breaks in the waveform.

Waveform Library

Go to the drop-down menu bar at the lower left corner of the Waveform Library window and select, Camshaft sensor (inductive).

Example inductive sensor

Further guidance

A CMP signals one or more fixed camshaft reference positions to the Engine Control Module (ECM), for example the arrival of cylinder one intake stroke.

A CMP sensor can also be referred to as a Cylinder Identification (CID) sensor or a phase sensor.

The ECM uses the camshaft sensor signal for accurate timing control of ignition, knock, injection, and variable valve phasing, etc.

An inductive CMP sensor consists of a circuit with a wire coil around a magnet. The sensor is accompanied by a reluctor ring, or trigger wheel, attached to the camshaft. The reluctor ring or trigger wheel, which may be configured with one or more teeth, holes or slots, periodically disturbs the sensor’s magnetic field and induces a circuit voltage. The induced voltage depends on engine speed: the faster the camshaft rotates, the greater the magnetic field disturbance.

If a unique reference mark exists for each cylinder, the camshaft position sensor signal can be used as a rapid start phase sensor: with this configuration a 4-cylinder engine can start within 180 degrees of crankshaft rotation (90 degrees of camshaft rotation).

A faulty camshaft sensor can cause multiple misfire, loss of engine performance, engine cutting out, limp-home mode operation, or engine cranking but not starting symptoms.

Possible faults are:

  • Short or open circuits and high resistance in the sensor coil or circuit.
  • Reduced sensor output due to excessive dirt and detritus on the sensor housing or reluctor.
  • Incorrect fitment or operation of the sensor or camshaft components, causing:
    • excessive gaps between the sensor and reluctor
    • damage to the sensor housing or reluctor
    • excessive camshaft movement or vibration

Diagnostic trouble codes

Selection of component related Diagnostic Trouble Codes (DTCs)

P0340 : Camshaft Position Sensor A - Circuit Malfunction (Bank 1)

P0341 : Camshaft Position Sensor A - Circuit Range/Performance (Bank 1)

P0342 : Camshaft Position Sensor A - Circuit Low Input (Bank 1)

P0343 : Camshaft Position Sensor A - Circuit High Input (Bank 1)

P0344 : Camshaft Position Sensor A - Circuit Intermittent (Bank 1)

P0345 : Camshaft Position Sensor A - Circuit Malfunction (Bank 2)

P0346 : Camshaft Position Sensor A - Circuit Range/Performance (Bank 2)

P0347 : Camshaft Position Sensor A - Circuit Low Input (Bank 2)

P0348 : Camshaft Position Sensor A - Circuit High Input (Bank 2)

P0349 : Camshaft Position Sensor A - Circuit Intermittent (Bank 2)

P0365 : Camshaft Position Sensor B - Circuit Malfunction (Bank 1)

P0366 : Camshaft Position Sensor B - Circuit Range/Performance (Bank 1)

P0367 : Camshaft Position Sensor B - Circuit Low Input (Bank 1)

P0368 : Camshaft Position Sensor B - Circuit High Input (Bank 1)

P0369 : Camshaft Position Sensor B - Circuit Intermittent (Bank 1)

P0390 : Camshaft Position Sensor B - Circuit Malfunction (Bank 2)

P0391 : Camshaft Position Sensor B - Circuit Range/Performance (Bank 2)

P0392 : Camshaft Position Sensor B - Circuit Low Input (Bank 2)

P0393 : Camshaft Position Sensor B - Circuit High Input (Bank 2)

P0394 : Camshaft Position Sensor B - Circuit Intermittent (Bank 2)

GT011-4

Disclaimer
This help topic is subject to changes without notification. The information within is carefully checked and considered to be correct. This information is an example of our investigations and findings and is not a definitive procedure. Pico Technology accepts no responsibility for inaccuracies. Each vehicle may be different and require unique test settings.

Suitable accessories

  • Premium 6-way breakout lead set

    £269.00

  • Back-pinning Probe Set

    £40.00

  • Flexible Back-pinning Probe

    £3.00

  • Large Dolphin/Gator Clips

    £10.00

  • Premium Test Lead: BNC to 4 mm, 3 m

    £47.00

  • Premium Test Leads: Set of four leads 3 m (TA125 - TA128)

    £179.00

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Guided test: Camshaft sensor - inductive