Camshaft sensor - AC excited type

The purpose of this test is to evaluate the correct operation an AC excited camshaft sensor based on the AC voltage supply and AC voltage return signal during engine run conditions.

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 offers 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 (to include relevant circuit/connectors):

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

How to perform the test

The sensor has three wires, one carrying the AC voltage input signal, a second the AC voltage output signal and a third earth cable.

  1. Connect PicoScope Channel A to the input signal, Channel B to the output signal and both channels to earth.
  2. Start the engine and allow it to idle.
  3. Minimise the help screen and with the Example Waveform on your screen PicoScope has already selected suitable scales for you to capture a waveform.
  4. Select GO on your screen or press the space bar to capture the data.

Example waveform

Waveform notes

This type of sensor is used on some of the GM/Vauxhall/Opel ECOTEC engines. This Cylinder Identification (CID) sensor differs in operation from the other inductive sensors by having an Alternating Current (AC) voltage supply to the CID sensor. The Electronic Control Module (ECM) supplies a high frequency of 100 to 150 kHz (100,000 to 150,000 cycles per second) to an exciter coil that is located close to a rotating disc.

The disc is located at the end of the camshaft and has a section removed that, when aligned with the sensor, allows the frequency to excite the receptor (through mutual inductance) and returns the signal to the ECM, indicating the position of number 1 cylinder.

As the frequency is so fast, the time scale should be set to 20us/division so that the oscilloscope can capture the frequency.

The CID sensor is used as a reference by the ECM to determine the camshaft's position, from which the correct timing for the sequential fuel injection can be determined.

Further guidance

This camshaft sensor differs in operation from the other sensors by having an Alternating Current (AC) voltage supply. The ECM supplies a high frequency of around 100 to 150 kHz to an exciter coil that is located close to a rotating disc.

The disc is located at the end of the camshaft and has a section removed that, when aligned with the sensor, allows the frequency to excite the receptor (through mutual inductance). The signal returns to the ECM, indicating the position of number 1 cylinder.

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)

GT013-5

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

  • PicoScope Battery Clip

    £2.75

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Guided test: Camshaft sensor - AC excited type