16 · Electrical

Heater plug control unit operation check

Make: Fiat
Model: 500 Factory Service Manual
Year: 2007–2024
Section: Engine starting › Heater plug control unit operation check

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Electrical equipmentHeater plug control unit operation check

HEATER PLUG CONTROL UNIT OPERATION CHECK

Check 5520CB

1.3 Multijet

STEP	CHECK TO BE PERFORMED	REMEDIAL ACTION IF THE CHECK IS NOT OK
1	Preheating control unit power supply check Turn the key to the MAR position Using an Examiner in Voltmeter mode, check that there is a 12 V battery voltage between pin 3 and earth Move on to Step 2	Restore the electrical continuity of the supply lead See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT Restore the 15 A fuse (F11) in the fuse box after having identified the cause of the problem. Replace main relay Replace the junction unit Op. 5505A13
2	Check earth connection Disconnect negative battery cable Disconnect the wiring from the glowheater plugs control unit Reconnect the negative battery cable Using an Examiner In Ohmmeter mode, connect between pin 1 of the wiring and earth Check that the resistance is less than 1 Ohm Move on to Step 3	Restore the electrical continuity of the earth lead See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
3	Check on preheating control unit activation control by engine control unit Turn the key to the ON position With the Examiner in voltmeter mode check that there is a voltage of 0 V between pin 2 and earth Check that the voltage switches to about 9 Volt after a few seconds Start the engine and check that the voltage switches firstly to 0 Volt and then to around 9 Volt Move on to Step 4	Restore the wiring between the engine management control unit and the heater plugs control unit See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT If the voltage is interrupted Replace the engine management control unit Op. 1060G80 DIESEL ELECTRONIC INJECTION CONTROL UNIT - R.R and carry out the correct operation renewal procedure
4	Check on return signal from preheating control unit to engine management control unit With the Examiner in voltmeter mode Turn the ignition to the ON position and check that there is a voltage of around 10 V between pin 5 and earth See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT Start the engine and check that the voltage switches to about 0 Volt Move on to Step 5	Restore the wiring between the preheating control unit and the engine control unit. If OK Replace heater plug preheating control unit Op. 5520C20 HEATER PLUGS CONTROL UNIT - R.R and carry out the correct operation renewal procedure
5	Check on power supply Check that there is a 12 Volt voltage present at pin 30 See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT Move on to Step 6	Restore the wiring between the preheating control unit and the fuse box on the battery Restore the power fuse after having identified the cause of the problem.
6	Heater plugs power supply check Start the engine and check that the battery voltage arrives correctly to the individual glow plugs during the preheating stage See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT The test can be considered over.	Restore the wiring between the preheating control unit and the glow heater plugs Replace the preheating control unit Op. 5520C20 HEATER PLUGS CONTROL UNIT - R.R and carry out the correct operation renewal procedure.

STEP

CHECK TO BE PERFORMED

REMEDIAL ACTION IF THE CHECK IS NOT OK

Preheating control unit power supply check

Turn the key to the MAR position

Using an Examiner in Voltmeter mode, check that there is a 12 V battery voltage between pin 3 and earth

Move on to Step 2

Restore the electrical continuity of the supply lead

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

Restore the 15 A fuse (F11) in the fuse box after having identified the cause of the problem.

Replace main relay

Replace the junction unit

Op. 5505A13

Check earth connection

Disconnect negative battery cable

Disconnect the wiring from the glowheater plugs control unit

Reconnect the negative battery cable

Using an Examiner In Ohmmeter mode, connect between pin 1 of the wiring and earth

Check that the resistance is less than 1 Ohm

Move on to Step 3

Restore the electrical continuity of the earth lead

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

Check on preheating control unit activation control by engine control unit

Turn the key to the ON position

With the Examiner in voltmeter mode

check that there is a voltage of 0 V between pin 2 and earth

Check that the voltage switches to about 9 Volt after a few seconds

Start the engine and check that the voltage switches firstly to 0 Volt and then to around 9 Volt

Move on to Step 4

Restore the wiring between the engine management control unit and the heater plugs control unit

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

If the voltage is interrupted

Replace the engine management control unit

Op. 1060G80 DIESEL ELECTRONIC INJECTION CONTROL UNIT - R.R

and carry out the correct operation renewal procedure

Check on return signal from preheating control unit to engine management control unit

With the Examiner in voltmeter mode

Turn the ignition to the ON position and check that there is a voltage of around 10 V between pin 5 and earth

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

Start the engine and check that the voltage switches to about 0 Volt

Move on to Step 5

Restore the wiring between the preheating control unit and the engine control unit.

If OK

Replace heater plug preheating control unit

Op. 5520C20 HEATER PLUGS CONTROL UNIT - R.R

and carry out the correct operation renewal procedure

Check on power supply

Check that there is a 12 Volt voltage present at pin 30

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

Move on to Step 6

Restore the wiring between the preheating control unit and the fuse box on the battery

Restore the power fuse after having identified the cause of the problem.

Heater plugs power supply check

Start the engine and check that the battery voltage arrives correctly to the individual glow plugs during the preheating stage

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

The test can be considered over.

Restore the wiring between the preheating control unit and the glow heater plugs

Replace the preheating control unit

Op. 5520C20 HEATER PLUGS CONTROL UNIT - R.R

and carry out the correct operation renewal procedure.

PROCEDURE FOR RESTORING CORRECT OPERATION OF PREHEATING SYSTEM

Each time any of the preheating system components (preheating control unit, glow heater plugs, engine management control unit, wiring) is replaced/renewed, a complete heater plugs activation plus heater plugs warning light flashing cycle (described below) should be carried out in order to allow the error in the engine management control unit to be correctly deleted and avoid the heater plugs warning light continuing to flash in the instrument panel even if there is no fault in the preheating system.

OPERATING CYCLE:

1. Turn the ignition ON and wait until the heater plugs warning light goes out (preheating stage).

2. Start the vehicle and wait until the preheating control unit is deactivated (the heater plugs warning light should be off during this stage)

3. If there is a fault in the preheating system, the heater plugs warning light should start flashing for 30 seconds.

4. At the end of this stage, turn the ignition OFF and repeat the starting process.

5. If at the end of the activation of the preheating control unit, the heater plugs warning light no longer flashes (defect no longer present), delete the error from the memory using the Examiner.

HEATER PLUG CONTROL UNIT OPERATION CHECK

Heater plugs control unit
Pin	Component
G1	Heater plug 1
G2	Heater plug 2
G3	Heater plug 3
G4	Heater plug 4
G5	N.C.
31	Earth
K	Preheating control unit control
86	+ 15 Supply
ST	N.C.
Di	Feedback signal
+30 Batt (Threaded pin)	Power supply

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Parts & tools for this job For 2007 Fiat 500

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