2.3 Fluid-level sensors

The vehicle is equipped with a number of fluid-level sensors, such as:

f luid-level sen sor fo r th e coo li ng syste m

The fluid-level sensor is a reed contact type. The sensor is provided with a micro switch which is influenced by a magnetic field outside the sensor.

If the fluid level drops, the switch will be operated by a float with a magnet in the tank or reservoir, and the contacts will close.

The closing of the contacts will ‘activate' a warning lamp.

Checking

The flu id-level sensors can be checked with a multimeter set to the resistance range.

2.4 Pressure sensors

The vehicle is equipped with a number of pressure sensors, such as:

pressure sensor to register the bag pressure in ECAS.

A diaphragm of semiconductor material (silicon) is incorporated in the pressure sensor.

If pressure is exerted on the diaphragm, it will bend.

This bending of the diaphragm will produce a change of resistance of the semiconductor material.

The diaphragm is part of a so-called bridge circuit.

The bending of the diaphragm will unbalance the bridge circuit, which causes the output signal to change.

The output voltage is directly proportional to the pressure applied (bending of the diaphragm).

Checking

The output voltage can be checked with a multimeter set to the direct voltage range.

2.5 Proximity sensors

The vehicle is equipped with a number of proximity sensors, such as:

sensor under the clutch pedal for E-throttle

cab lock sensor

mechanic rear axle lift system

Inductive proximity sensors

A changing electromagnetic field is generated by a pulsating current in a coil (oscillation).

If a metal object is introduced into the electromagnetic field, eddy currents will occur in that metal object.

These eddy currents will 'damp' the magnetic field in the coil, so that the current taken up in the coil will change.

This change will result in an output voltage.

Checking

Placing a metal object in front of the sensor (inductive sensor) makes it possible to check the output voltage with a multimeter set to the direct voltage range.

3. Inspection and adjustment

   1. Checking electrical systems

Special tools that may be used, are:

• DAVIE 2.0

multimeter, preferably digital

• DELSI 2

DAVIE 2.0

For information on how to use DAVIE 2.0. see the instructions supplied with the DAVIE equipment.

Multimeter

For the use of a digital multimeter, see the instructions supplied with the meter and the section‘Signal measuring'.

DELSI

DELSI stands for DAF Electronic Simulator.

A road speed signal is required for testing a number of electronic systems.

DELSI 2 (DAF no. 694941) is an electronic road speed simulator which can only be used in combination with a compact tachograph.

DELSI is connected to the road speed sensor plug on the gearbox.

To connect the DELSI, you must first break the seal on the connector. The road speed signal can be regulated with a rotary knob.

The road speed setting can be read on the tachograph.

For a reliable operational test the road speed should be above 20 km/h.

Note:

Remember to seal the road speed sensor plug again after DELSI has been used.