356027 - L26 (ELECTRIC) AIR PREHEATING IS NOT ACTIVATED AT LOW OUTSIDE TEMPERATURES

The outside temperature information is correctly displayed on the reconfigurable matrix.The electrical pre-heating device (only fitted on the JTD versions) consists of two (PTC) resistances with different resistance values which develop a maximum power of 700 W when a current passes through; when one of the two resistances or both of them are activated, the climate control system control unit is capable of modulating the interior heating;

the system can only be activated in the following circumstances: the system can only be activated in the following circumstances: 1) Ignition on and climate control switched on 2) Outside temperature below 20°C 3) Coolant temperature below 64°C 4) Battery voltage not less than 12.2 V 5) Engine rpm higher than 700 rpm

STEP	OPERATIONS TO BE CARRIED OUT	TEST RESULTS
1	CHECK USING DIAGNOSTIC EQUIPMENT	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Using the diagnostic equipment (Examiner or other instruments) connected, check the following information at the CAN network: no control unit not activated; that there are no faulty control units; no control unit with faulty CAN line;	Move on to Step	1. Presence of faults	1. Continue following the instructions for the diagnostic equipment
			2. Error detected in the climate control system control unit	Move on to Step
			3. Error detected in the engine management control unit	Move on to Step
2	CHECK USING DIAGNOSTIC EQUIPMENT	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Keeping the diagnostic equipment (Examiner or other instruments) connected to the diagnostic socket, check: that there are no faults in the climate control system node parameter plausibility	Move on to Step	1. Presence of faults	1. Continue following the instructions for the diagnostic equipment
			2. Parameters not plausible	2. Continue following the instructions for the diagnostic equipment
			3. No communication between climate control system control unit	3. Restore connection between the climate control unit and diagnostic connector (Wiring Diagram ) E6020 AIR CONDITIONING
3	CHECK USING DIAGNOSTIC EQUIPMENT	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Keeping the diagnostic equipment (Examiner or other instruments) connected to the diagnostic socket, check: that there are no faults in the engine management node parameter plausibility	Move on to Step	1. Presence of faults	1. Continue following the instructions for the diagnostic equipment
			2. Parameters not plausible	2. Continue following the instructions for the diagnostic equipment
			3. No dialogue with the engine management control unit	3. Restore the connection between the engine management control unit and the diagnostic connector (Wiring Diagram ) E5050 DIESEL ENGINE ELECTRONIC MANAGEMENT
4	CHECK USING DIAGNOSTIC EQUIPMENT	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Keeping the diagnostic equipment (Examiner or other instruments) connected to the diagnostic socket, carry out the active diagnosis of the heating resistance relay feeds	Move on to Step	Relay is not activated	Check the condition of the relay operating circuit, if necessary, replace the relay (Wiring Diagram ) E6020 AIR CONDITIONING
5	PTC RESISTANCES ELECTRICAL POWER CIRCUIT CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check the continuity of the power (supply) circuit for the resistances from the engine compartment junction unit to the resistances	Move on to Step	Circuit broken	Restore the connection between the engine compartment junction unit and the resistances (Wiring Diagram ) E6020 AIR CONDITIONING
6	PTC RESISTANCES CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check the electrical continuity of the resistances (Wiring Diagram ) E6020 AIR CONDITIONING	Move on to Step	Resistances broken	Replace PTC resistances
7	CHECK ON CORRECT OPERATION	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check that the fault is no longer present		Fault persists	Replace the climate control system control unit    See in Op. 5040D18 Air conditioning CONTROL UNIT - R.R.