Iveco Daily. Manual - part 363

 

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Iveco Daily. Manual - part 363

 

 

20

ELECTRIC/ELECTRONIC SYSTEM

D

AILY

Base - May 2004

The  electric  system  is  traditionally  a  single-pole  system.  The  body,  the  frame,  the  metal  container  of  electromechanical

components act as equipotential return conductor to the generator, as any point of their metal structure or any negative terminal

not isolated is at the same reference potential or EARTH. This is why the earth has been chosen as reference to the whole system,

conventionally giving it the value of zero.
Due to obvious reasons of construction, in the negative network of the system there are various earth points located on the

vehicle in relation to the location of the components on the frame, engine and body.
On the other hand, ideally, all the equipment should be connected to only one earth point in order to provide them, particularly

for electronic devices, a clearly defined earth reference.
For the above-mentioned reasons it is necessary to distinguish the supply earth or system earth, characterised by strong direct

current  intensity  (>  1  A  for  electromechanical  components),  from  the  analogue  earth,  characterised  by  wave  shapes  at

determinate frequencies and very low current intensity (mA, µA) of electronic systems.
The definition of signal earth or analogue earth depends on the sensitivity of the electronic systems to EMC (electromagnetic

compatibility), as parasite signals emitted by the systems on board or outside the vehicle, induce failures and/or deterioration of

the systems themselves. The best solution for a signal earth is connection with the battery negative terminal.
In order to minimise both continuous and transient disturbance or interference generated by parasite radiation, it is of the utmost

importance to always bear in mind that the satisfactory efficiency of the reference plane or system earth depends on the excellent

conductivity characteristics (contact resistance tending towards zero) in each of its connection points.
Briefly, we can say that the earth understood as equipotential electrical conductor, i.e. as potential reference for all the

electric/electronic components on board, is subdivided into system earth and analogue earth.

IDEAL EQUIPOTENTIAL EARTH NETWORK

Ba. Battery - R. Loads - Rz. Frame impedance - M

1

, M

2, 

M

3.

 Earth

Figure 18

6616

ELECTRIC/ELECTRONIC SYSTEM

21

D

AILY

Practical advice

The negative cables connected to an earth point must be as short as possible and connected to one another in a "star" connection,

trying to tighten them neatly and adequately.
Additionally, for electronic components the following instructions should absolutely be followed:
- Electronic control units must be connected to the system earth when they have a metal container.
- The negative cables of electronic control units must be connected to both a system earth point, for example the dashboard

earth (avoiding "serial" or "chain" connections), and to the negative terminal of the battery/ies.

- Though they are not connected to the system earth/battery negative terminal, analogue earths (sensors) must be perfectly

insulated. Therefore, particular care should be given to the parasite resistances of the terminals: oxidation, clinching defects,

etc.

- In the presence of jointing connectors the unscreened section d, near them, should be as short as possible.
- The cables should be laid on parallel with the reference plane, i.e. as near as possible to the frame/body structure.
- Additional electromechanical systems should be carefully connected to the system earth and must not be set at the side

of the cables of electronic components.

SCREENING BY METAL BRAID OF A CABLE TO AN ELECTRONIC COMPONENT

C. Connector - d. Distance  ! 0

Figure 19

88039

22

ELECTRIC/ELECTRONIC SYSTEM

D

AILY

Base - May 2004

In order to eliminate earth, supply, outer/inner lighting bridges between components, ultrasonic welding points have been used.
These are not easily identifiable as they appear along the cables inside the corrugated tube of the various harnesses and they are

isolated from the cables through heat-shrinking sheaths or insulating plastic.
Generally, the cables of the components converge on one side in the different welding points, while on the other only one cable

connects them with the earth or supply.
It is also possible to have several welding points connected to one another in which several cables converge on both sides of

the welding. In this case, the earth or supply cable will be connected to the last weld of the series.
Ultrasonic welding brings considerable advantages, including:
- reduction of electromagnetic interference outside the vehicle
- the almost total reliability of the electric system, due to elimination of the bridges, with lower possibility of faults.

ULTRASONIC WELDING

A. Wiring diagram - B. Technical layout

CONNECTION BETWEEN COMPONENTS

A. Connection through bridges - B. Connection through ultrasonic welding point

B

A

B

A

Figure 20

4886

8576

8577

Specifications for use
Vehicle electric system rated voltage:

12 V

Suitable for coupling with battery of any capacity

It must work with the battery connected.
Connection with inverted polarity is not allowed.
Operating specifications
Rated voltage

14 V

Rated current delivery

110A

Drive side direction of rotation

clockwise

Maximum continuous speed

≤ 12.000 min

-1

Storage temperature

-40 °C / +110 °C

WIRING DIAGRAM

TECHNICAL VIEW

03000

Figure 21

Figure 22

8649

8656

ELECTRIC/ELECTRONIC SYSTEM

23

D

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MAIN COMPONENTS OF POWER

NETWORK
BOSCH KCBI 14V 110A Alternator

 

 

 

 

 

 

 

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