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ADDITIONAL HEATER - Description

The supplementary heater aids coolant heating immediately following start-up and during running so that the engine heats up faster and engine
service temperature and passenger compartment heating are maintained at optimal levels.

The device works completely automatically and is active only when the engine is running with outdoor temperatures less than or equal to +5° C and
coolant temperature lower than 60° C.

When coolant temperature reaches 61° C, the control unit reduces burner power and cuts off operation when the temperature reaches 72° C. It is
re-activated automatically when the fluid temperature drops to 60° C. If fluid temperature begins to drop immediately after reducing burner power,
the control unit cuts in to restore full power.

For further details see Characteristic of working principle 5020L additional heater .

The control unit supply line is protected by a fuse in the engine compartment junction unit and a relay located in the services compartment (behind
the engine bulkhead).

The relay supply line is protected by a fuse located in the junction unit.

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ADDITIONAL HEATER - Functional description

Additional heater control unit M75 is supplied at pin 1 (connector B) directly from the battery. via the line protected by fuse F23 of the engine
compartment junction unit B1.

The earth is taken to pin 2 (connector B) via additional heater relay J36, switch I20 and relay T1 of junction unit B2.

When relay T1 is energised via the line (15/54) its contact supplies the coil of additional heater relay J36 via fuse F6. Control unit M75 receives an
earth signal via its contact.

Pin 3 of connector A of M75 receives a signal from the appropriate temperature sensor K79 , which measures air temperature within the engine bay.

The sensor only works with the engine running; it receives a reference signal from alternator (D+); this signal is low (earth) when the alternator is
not turning. The signal becomes high (12 V) and supplies the sensor when the engine is running. E5010 STARTING AND RECHARING

Pin 6 of connector A controls additional heater pump N44 , which is earthed through inertia switch I50 . In case of impact, this cuts off the circuit to
prevent the danger of fuel emerging.

If the intertia switch is operated it de-energizes the relay J36.

Control unit M75 is equipped with a self-diagnostic system that may be used by connecting the unit to connector R10 through pin 2 of connector A.
E8010 DIAGNOSTIC MULTIPLE CONNECTOR .

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ADDITIONAL HEATER - Location of components

Component code

Name

Assembly reference

Terminal board

A10

Alternator

A10

Alternator

5530A

Junction unit

5505A

Junction unit

5505A

Dashboard junction unit (CPL)

Junction unit

5505A

MAXI FUSE box

B38

Additional heater fuse

B99

Battery fuses junction unit (CBA)

5530B

C10

Front left earth

C15

Facia earth, driver's side

C30

Rear left earth

C31

Rear right earth

Front-dashboard coupling

Engine front connection

Rear - front coupling

Rear-engine compartment coupling

Recharging front connection

D19

Dashboard / battery coupling

D22

Additional heater junction

D25

Dashboard-left rear coupling

D25

Dashboard-rear coupling left

Ignition switch

5520A

I50

Inertial switch

1040A

J36

Additional heater relay

5020M

J36

Webasto pump inhibitor relay.

K79

Air temperature sensor (additional heater)(

K79

Interior temperaature. sensor for additional heater

M75

Additional heater control unit

N44

Additional heater pump

O25

Additional heater resistance

R10

Multiple tester connection

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ADDITIONAL HEATER - Wiring diagram

Component code

Name

Assembly reference

Terminal board

A10

Alternator

A10

Alternator

5530A

Junction unit

5505A

Junction unit

5505A

Dashboard junction unit (CPL)

Junction unit

5505A

MAXI FUSE box

B38

Additional heater fuse

B99

Battery fuses junction unit (CBA)

5530B

C10

Front left earth

C15

Facia earth, driver's side

C30

Rear left earth

C31

Rear right earth

Front-dashboard coupling

Engine front connection

Rear - front coupling

Rear-engine compartment coupling

Recharging front connection

D19

Dashboard / battery coupling

D22

Additional heater junction

D25

Dashboard-left rear coupling

D25

Dashboard-rear coupling left

Ignition switch

5520A

I50

Inertial switch

1040A

J36

Additional heater relay

5020M

J36

Webasto pump inhibitor relay.

K79

Air temperature sensor (additional heater)(

K79

Interior temperaature. sensor for additional heater

M75

Additional heater control unit

N44

Additional heater pump

O25

Additional heater resistance

R10

Multiple tester connection

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