DAF 95 XF series Service Manual

DAF 95 XF series Service Manual
DAF 95 XF series PDF Repair manual

TROUBLESHOOTING DAF Trucks 95 XF series
The following test equipment and tools can be used to localise faults.

  1. The best instrument for this purpose is a digital multimeter. This instrument enables voltages, currents and resistances to be measured without reading errors, and it can trace virtually all faults.
  2. Many but not all faults can be traced in a simple way by using warning lamps. However, faults which are caused by a poor earth connection can in general not be traced via a warning lamp or a buzzer.

The most frequently occurring faults are:

  • short circuit
  • open circuit
  • earthing problems (poor earth connection caused by corrosion).

SHORT CIRCUITS DAF 95 XF series
A short circuit is caused by a positive wire shorting somewhere to earth. In most cases this will cause a fuse to blow. 70W is then used to trace this fault. First check the diagram to see which consumers are protected by the fuse and then switch them all off.

Remove the fuse and replace it with a test lamp. Then, one by one, switch the consumers on and off. If the test lamp starts burning very brightly when a consumer is switched on, it is almost certain that the fault is in the wiring of that particular consumer. Check the diagram to see which connector is used to connect this consumer. Remove the first wiring connection (looking from the fuse). If the test lamp continues to burn brightly, the fault is between the fuse and this wiring connection.

However, if the test lamp stops burning, the fault is somewhere further on in the wiring. Restore the wiring connection and disconnect the next one. If the test lamp continues to burn brightly, the fault is between these two wiring connections. However, if the lamp stops burning again, the fault tracing procedure must be continued. In this way the faulty section of the wiring can be found.

OPEN CIRCUITS DAF 95 XF series
Suppose a consumer is not functioning. The fault may then be in the consumer itself, or the wiring may be interrupted. First switch on the consumer and check for voltage with the test lamp. If no voltage is present, first check whether the fuse is still intact.

If there is voltage at the fuse, the wiring must be checked again from the fuse to the consumer. Every wiring connection must be checked. If there is no voltage at one of these wiring connections, the interruption is between this connection and the connection checked second-last.

If voltage was found at the consumer, there is still the possibility of an interruption in the wiring from the negative terminal of the consumer to earth. This can be checked with a test lamp. Make sure the circuit concerned is connected up.

Connect one end of the test lamp to earth and the other end to the negative (-) terminal of the component to be checked. If the test lamp starts burning, the earth connection of the component is interrupted. If the test lamp does not come on, the earth connection of the component will in most cases be in good order. If the positive and negative connections are both in good order, the consumer is defective and must be replaced.

EARTHING PROBLEMS DAF 95 XF series
Problems with the earth connections are mostly caused by corrosion on the contact surfaces of electrical connections. Earthing problems can only be traced with a (preferably digital) multimeter. Digital, because this kind of problem usually involves only a few volts and the readings of an analog meter are not precise enough for this purpose.

To establish whether a certain earthing point has a good earth connection, measure with a voltmeter between the battery negative pole and the earthing point in question. Now switch on as many consumers as possible. If there is a correct earth connection, no voltage should be found. In practice, however, a loss of approx. 0,5V will often be measured. If the reading is higher, the earth connection must be checked carefully. In this way the earth connections of all the consumers can be checked and measured.

ENGINE SPEED AND VEHICLE SPEED SENSORS
The engine speed and vehicle speed sensors are inductive sensors. The vehicle is equipped with a number of inductive sensors, such as:

  • engine speed sensor
  • ABS sensor
  • vehicle speed sensor.

Operating principle
An inductive sensor is composed of a permanent magnet (1), a core (2) and a coil (3). When the inductive sensor is situated between two teeth, the lines of force of the magnetic field will run directly from the north pole to the south pole via the housing.

The moment a tooth approaches the inductive sensor, the lines of force of the magnetic field will run from the north pole to the south pole via the housing, the teeth of the wheel, and the core. In this situation more lines of force will pass through the core, which will give an increased magnetic-field intensity. As a result of this change in the magnetic field, an alternating voltage will be generated in the coil. The value of the generated alternating voltage depends on the rotation speed of the toothed wheel and the air gap between sensor (core) and tooth.

From alternating voltage to “pulse train” The output signal of the inductive sensor is used by the various electronic units and analog meters/gauges (rev counter, tachograph). The electronic unit has a microprocessor, which can only process digital signals (pulses). Therefore, the sine-wave signal should be converted into a “pulse train”. Similarly, the meters/gauges (rev counter, tachograph) only respond to a “pulse train”.

Duty cycle of vehicle speed signal
The linear characteristic of the duty cycle (%) versus the vehicle speed (V) is plotted in the graph opposite. This characteristic applies to all vehicle types. Checking: The alternating voltage signal can be checked with a multimeter set to the alternating voltage range. The “pulse train” (square-wave voltage) can be checked with a multimeter set to the direct voltage or duty cycle range.

FLUID-LEVEL SENSORS
The vehicle is equipped with a number of fluid-level sensors, such as: fluid-level sensor for the cooling system 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 fluid-level sensors can be checked with a multimeter set to the resistance range.

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.

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.

REMOVING AND INSTALLING CONTACTS FROM CONNECTORS
Contact kit A (DAF no. 0694960) If additions are made to the wiring, a contact may have to be removed from the connector. For this purpose special ejectors have been developed, which are included in the contact kit. To facilitate the selection of the contact, crimping tool and ejector, a sticker has been affixed to the inside of the box.

The information given on this sticker is to be interpreted as follows:At the top is the DAF no. of the contact shown. Roman numerals I and II, shown under the illustrations, refer to the crimping tool to be used.

The numeral or letter added to Roman numeral I or II indicates the hole in the tool in which the contact is to be placed. Roman numerals III to VII refer to the type of ejector to be used for removing the contact from the connector. The information at the bottom refers to the wire core cross sectional area suitable for the contact.

Contact kit B (DAF no. 1240065) Additional crimping and ejector tools are required for SCAT contacts and for micro-timer contacts. To facilitate the selection of the contact, crimping tool and ejector, a sticker has been affixed to the inside of the box.

INSTALLING CONTACT UNITS ON ELECTRICAL WIRES
The increasing application of electronics in vehicles has made it necessary to use new types of connectors and contacts. This has resulted in the use of relatively small contacts. More attention must therefore be paid to the connections as a whole.

In addition, the number of connections has considerably increased, so that the wiring harnesses have become thicker. To keep the wiring harnesses manageable, a new type of wiring is now being used:

  1. Wires with a core section of 1 to 2.5 mm2 and reduced insulation thickness, retaining the mechanical properties, resistant to temperatures up to 70C (in accordance with DAF standard 9502). These wires are not suitable for engine and gearbox wiring.
  2. Wires with a core section of 1 to 120 mm2 and normal insulation thickness, resistant to temperatures up to 105C (in accordance with DAF standard 9504).

REMOVAL AND INSTALLATION OF CONTACT UNITS OF CONNECTORS WITH ADDITIONAL CONTACT LOCK
Some connectors have an additional contact lock. Such a connector is in halves. The upper half (wire entry side) together with the lower half constitutes the additional contact lock.

In order to unlock the additional contact lock, slightly push the upper half of the connector in the direction shown by the arrow (on the connector housing). Now you can correctly position the wires with their contact units. Contact units with an additional contact lock are removed using the special ejector tool from contact kit A or B. Correctly position the wires with their contact units. Once the contacts have been fitted, push back the connector until it locks.

Master switch diagram 95XF series
Master switch C555 should be switched on manually outside the cab. The master switch can be switched off:

  1. Manually (outside the cab)
  2. Pneumatically (inside the cab)

Relay G186 is activated when the voltage on pin 4 drops out. Engine stop valve B082 will then be activated for 60 seconds. If pressure switch E559 is open, engine stop valve B082 is not activated. Switch A can be used to switch off the master switch pneumatically inside the cab. This also involves the opening of pressure switch E559.

The electric master switch C669 must be switched on manually outside the cab. The electric master switch can be switched off in the following ways:

  1. Manually (outside the cab)
  2. Electrically (outside the cab)
  3. Electrically (inside the cab)

When switch C667 or C668 is closed, the relay of the electric master switch is activated, so that the electric master switch is switched off. As soon as the electric master switch is switched off there will be no voltage on the relay. When the electric master switch is switched off, the engine continues to operate. D+ will then be connected to earth.

40A CONNECTOR
This connector (A) is a two-pole connector. The supply voltage for this connector is branched off from the power supply before contact via fuse E168. It is possible to connect a connector to a contact block. This way you get a central connection point for supply and earth.

CHARGING CIRCUIT/STARTING MOTOR/CONTACT/STARTER SWITCH
CONTACT CIRCUIT
If a connection is made between contacts 1 and 6 with contact/starter switch C539, a voltage is applied through fuse E037, switch C539 and wire 1130 to contact 85 of relay G178. Because relay G178 is activated, a connection is made between contacts 30 and 87 and a voltage is applied through fuse E037, wire 1100, the contacts 30 and 87 of relay G178, wire 1147, and through fuses E027 and E052 to the electronic unit of converter 24 V/12V D525 and the work light switch C725.

If a connection is made between contacts 1 and 4 with contact/starter switch C539, a voltage is applied through fuse E037, wire 1100, switch C539 and wire 4001 to contact 85 of relay G015. As a result, relay G015 is activated, so that wire 1000 is connected to wire 1010. Now voltage is applied to the supply behind contact circuit (connection point 1010) and, through resistor B036 and diode D668, to the connection points D+ of the alternator A502, connection point 85 of relay G303 and to the electronic unit CWS D853.

START CIRCUIT
When the engine is started, a connection is made between the contacts 1 and 2 with contact/starter switch C539. The voltage now runs from the batteries through wire 1000, fuse E037, connection 1–2 of the contact/starter switch, wire 4002 and contacts 30 and 87 of relay G303, wire 4009, to connection point 50 of starting motor B010. The coil of the starting motor relay is now activated, so that a voltage is supplied to the starting motor, as a result of which the motor will start operating.

As soon as the engine is running, the voltage on connection D+ of the alternator will increase to the adjustment voltage (= board voltage). This voltage will cause the coil of relay G303 to be energised. It will break the connection between 30 and 87A and connects 30 to 87. As a result, wire 4002 is disconnected from wire 4009. In