ADDITIONAL HEATER - Functional description

1.9 JTD 8v, 1.9 JTD 16v

Functional description

The relay J36 controls the engagement of the first additional heater coil

The relay is supplied from the fuse B38.

The relay J37 controls the engagement of the other two additional heater coils.

The supply for relay arrives from the line for maxifuse PTC2, located on the battery, connector B99.

the ignition (INT/A) protected by fuse F49 of the junction unit under the dashboard B2.

This supply is cut off in the case of overheating, via the safety switch l95.

Control unit M75 controls device operation: it is supplied by an igntiion-operated line (INT) protected by fuse F49 of underfacia control unit B2, and connected via the CAN line to Body Computer M1and the other network nodes.

The climate control unit M75 sends the enabling signal for engaging the first resistance O25A to excite relay J36 and a signal to activate the two coils O25B at relay J36.

Another dedicated signal controls activation of the first speed of air fan N85, supplied by ignition-operated line (INT/A) of relay T8 and dedicated fuse F8 of engine bay control unit B1 - it is operated at the first speed in any case if the supplementary heating device is on. See E6020 AIR CONDITIONING.

1.9 JTD 8v, 1.9 JTD 16v · Automatic Air Conditioning

Functional description

The relay J36 controls the engagement of the first additional heater coil

The relay is supplied from the line of the fuse B38.

The relay J37 controls the engagement of the other two additional heater coils.

The supply for relay arrives from the line for maxifuse PTC2, located on the battery, connector B99.

the ignition (INT/A) protected by fuse F49 of the junction unit under the dashboard B2.

The climate control unit M70 sends the enabling signal for engaging the first resistance O25A from pin 8 of connector B: this signal excites relay J36.

The climate control unit M70 sends a signal for enabling the engagement of the two resistances O25B from pin 7 of connector B: this signal energizes the relay J36.

1.9 JTD 8v, 1.9 JTD 16v · Webasto

Functional description

The additional heater unit is connected to the vehicle electrical system through connector D8 D.

This connector, pin G, receives a direct supply through the line protected by the maxifuse PTC2, located on the battery, connector B99, pin E is earthed.

Pin A of D8 D is connected to the outside air temperature sensor K79 which, in turn, receives the reference supply from the alternator (D+ pin signal, pin 19 of connector A of M1 ): in this way the signal for the outside temperature is only sent to the additional heater control unit if the engine is running.

Pin D receives the on signal from the remote control receiver M74.

This receiver is supplied by a direct line, protected by fuse F39 of the junction unit under the dashboard B2.

Pin B receives the inertia switch I50 earth signal which cuts off the circuit in the case of an impact and prevents the dangerous delivery of fuel.

The additional heater control unit is equipped with an autodiagnostic system which can be used: by connecting the unit to connector R10: it receives signals from pin 4 of D8 Dvia the diagnostic K line See E8010 DIAGNOSTIC MULTIPLE CONNECTOR.

The additional heater control unit M75 controls the engagement of the fan N85 with the heater on: a suitable signal reaches pin 4 of M75 from pin F of D8 D.

The control unit M75 receives a supply controlled by the ignition (INT/A) - pin 5 - from the line protected by fuse F31 of the junction unit under the dashboard B2 and controlled by relay T8 of the specific fuse F8 for the engine compartment junction unit B1; the supply controlled by the ignition (INT) - pin 2 - arrives from the line protected by fuse F49 of the junction unit under the dashboard B2.

The power supply from the line from the specific fuse B38 reaches pin 8; pin 3 is earthed.

The signal for switching on the fan N85 departs from pin 9 of M35.