Crankshaft Angle Sensor (CAS) (Peugeot Eurovans 806)

The crankshaft angle sensor (CAS), which determines fuel injection time and ignition timing, is located near the flywheel (see illustration 11.9). The crankshaft angle sensor consists of an inductive magnet that emits a magnetic field. The sensing ring, attached to the flywheel, includes 60 steel pins installed around the perimeter at equal intervals. When the flywheel rotates, the pins also rotate in the magnetic field, and an AC voltage signal is sent to the electronic control unit to determine the rotation speed. Two sensing pins are missing, thus serving as a TDC reference mark. As the flywheel rotates, the two missing pins cause changes in the signal that is returned to the electronic control unit, thus determining the TDC position.



Peak-to-peak voltage signal (if you look at the oscilloscope) the voltage can vary from 5 V at idle to over 100 V at 6000 rpm. The electronic control unit uses a digital converter to convert the AC pulse into a digital signal.

Crankshaft Angle Sensor (CAS) Voltage Values

Terminal numbers

CAS	ECM	Element	Volts	State	VAC* (rpm)	VAC* (full swing)
2	48	Sensor feedback signal	0.25 max
3	54	Grounding	0.25 max
1	49	Output voltage		When cranking/idling	0.7V+	2.0V+
				At idle	4.0B+	11.0V+
				On the move	5.0B+	14.0V+

* VAC - alternating current voltage See illustration 11.10, 11.11

Resistance values of the crankshaft angle sensor (CAS

)

Terminal numbers

CAS	ECM	Resistance (I)
1 and 2	49 and 48	300 - 400
1 and 3	49 and 47	Infinity
2 and 3	48 and 47	Infinity

Influence of external factors

• Incorrect air gap
• The flywheel is faulty or incorrectly installed

Checking the crankshaft angle sensor (CAS) (general check)

1. Inspect the crankshaft angle sensor multi-pin connector for signs of corrosion or damage.



2. Make sure the connector pins are properly installed and have good contact with the crankshaft angle sensor multi-pin connector.

3. Remove the crankshaft angle sensor from the engine block. Inspect the end face for signs of corrosion and damage.

4. Measure the resistance of the crankshaft angle sensor and compare the obtained value with the specifications. See resistance determination tests at the end of this chapter.

5. The presence of the faults listed above is a common cause indicating a defective sensor or a failure in the signal coming from the crankshaft angle sensor.

Checking the crankshaft angle sensor output signal with an oscilloscope

When turning the crankshaft

Note: This check should be performed with the engine off.

1. Disconnect the crankshaft angle sensor (CAS) or electronic control module (ECM) multi-pin connector.

2. Connect an oscilloscope between terminals 1 and 2 of the crankshaft angle sensor or the corresponding terminals of the ECM multi-pin connector.

3. Turn the crankshaft, the instrument reading should be approximately 4.0 to 5.0 V - minimum (full swing) (see illustration 11.12).

4. Check the uniformity of peak values. If one or more values are much lower than the others, this indicates damage to the crankshaft angle sensor cam.

5. If there is no signal or if the signal is very weak or unstable:

Measure the resistance of the crankshaft angle sensor (CAS).

• Check the sensor for damage and contamination with dirt or oil.
• Check the flywheel for damage.
• Check the crankshaft angle sensor (CAS) air gap (if possible).

Information copied from the resource: PEUGEOTBOOK.ru

With the engine running

1. Connect the crankshaft angle sensor (CAS) or electronic control module (ECM) multi-pin connector and (where possible) bend back the insulation to obtain voltage by connecting the voltmeter probes to the crankshaft angle sensor terminals (or connect a terminal block (TB) between the ECU multi-pin connector and the ECU).

2. Best results are usually obtained by connecting the probes to the (+) terminal, although quite often a waveform can be obtained by connecting the probes to the ground terminal of the crankshaft angle sensor.

3. Run the engine at different speeds and check the stability of the signal.

Checking the crankshaft angle sensor output signal using an AC voltmeter (CAS)

When turning the crankshaft

Note: This check should be performed with the engine off.

1. Disconnect the crankshaft angle sensor (CAS) or electronic control module (ECM) multi-pin connector and connect an AC voltmeter between the CAS terminals.

2. Turn the crankshaft. The meter reading should be approximately 0.7 V(rpm) (minimum), although most good sensors provide an output voltage of more than 1.4 V(rpm).

Note: An AC voltmeter at least proves that the crankshaft angle sensor is producing a signal. However, AC voltage is an average voltage, so it does not accurately indicate damage to the crankshaft angle sensor cams. Testing the Crankshaft Angle Sensor (CAS) Output Signal with an AC Voltmeter

With the engine running

Note: Measuring output voltage with the engine running will be a little tricky.

1. Connect the multi-pin connector and peel back the insulation (where possible), to obtain voltage by connecting the voltmeter probes to the sensor terminals.

2. Start the engine and let it idle. The alternating current (VAC) voltage (rpm) can be displayed at different engine speeds by adjusting the throttle valve.

Note: This is possible (even probably), that the engine will not start with the voltmeter connected. Alternatively, if the voltmeter is attached while the engine is running, it may stall or even misfire when the throttle valve opens.

3. First, start the engine at 2000 rpm, and then connect the voltmeter probes, the high output voltage at this speed is usually enough to prevent the engine from stalling and allow it to continue running. The engine will not be damaged if the specifications are followed when connecting the voltmeter.

Checking the resistance of the crankshaft angle sensor (CAS) using an ohmmeter

1. Disconnect the crankshaft angle sensor (CAS) or electronic control module (ECM) multi-pin connector and connect an ohmmeter between the two terminals leading to the sensor.

2. Record the obtained resistance and compare it with the resistance values of the crankshaft angle sensor (CAS).

Note: Even if the resistance meets the specifications, this does not prove that the crankshaft angle sensor can produce an acceptable signal.

Shielded crankshaft angle sensor (CAS) wire

1. The crankshaft angle sensor (CAS) may have a shielded wire (not in all cases). Locate the multi-pin connector of the electrical wiring or disconnect the multi-pin connector of the electronic control module (ECM).



2. Place the ohmmeter probe on one of the sensor terminals No. 1 or No. 2.

3. Apply the other ohmmeter probe to the terminal of the shielded wire. The device should show infinite resistance.

4. Disconnect the ohmmeter probe from the shielded wire terminal and connect it to ground. The reading should also be infinity.

Note: On some systems, the crankshaft angle sensor shield wire is connected to the crankshaft angle sensor ground wire. In this case, the presence of conductivity will be registered by the ohmmeter, and this is normal for this vehicle. Refer to the wiring diagrams to determine which wires connect to the crankshaft angle sensor.