Introduction
The radiator fans are powered via a specific relay, which is enabled by the engine control unit.
Component assembling position

A injection relay; b etv relay (throttle valve actuator motor), c radiator fan relay, d engine control unit.

Location of right hand fan connection.

Location of left hand fan connection.
Connection wiring diagram

Ccm engine control connection, t radiator fan relay, a key on power (+15 from hands free relay 30), r battery power (+30), l left hand fan, r right hand fan, 85 light blue/black - lb/bk, 30 red/green - r/g, 86 red/black - r/bk, 87 red/grey - r/gr.
In the event of fault
In the event of a radiator fan relay fault, the radiator fans themselves do not work. The relay is not commanded by the ecu.
Fault codes generated and possible correlated faults fault codes generated by the engine control unit and displayed by the dds (fan relay diagnosis):
Note
Check integrity of electric circuit - short-circuit to vdc = with dashboard on, using a voltmeter, a voltage is measured between the wire tested and ground.
Check integrity of electric circuit - short-circuit to ground = with the battery cables disconnected, using an ohmmeter, continuity is detected between the wire tested and ground.
Check integrity of electric circuit - open circuit = with the battery cables disconnected, using an ohmmeter, no continuity is detected between the two ends of the wire tested.
The dashboard service display shows the error "fan relay" and the eobd warning light activates.
Possible correlated faults: coolant reaches boiling point but radiator fans not working. Check:
The radiator fan relay may be actuated from the dds to check radiator fan function.
The fans are normally activated at 103 and switched off at 101C.
If none of the aforementioned tests identify the problem and the radiator fan relay is in proper working order, replace the engine control unit.
Component replacement methods
No special measures are necessary in order to replace the radiator fan relay.
Starter motor relay
Engine speed-timing sensorGearchange mechanism
Return spring
Washer
Special screw
Gear pawl assembly
Interlock plunger holder
Sealing washer
Detent ball spring
Ball
Circlip
Selector claw return spring
Shim washer
Ring
Nut
Selector drum control fork
Gearchange lever pin
Shaft with gearchange lever arm
Gearch ...
Refitting the intake manifold and coolant union
Apply prescribed threadlocker to the fitting (12), start it with seal (24)
and tighten it to a torque of 2.5 Nm (min. 2 Nm -
max. 3 Nm) (sect. 3 - 3, Frame torque settings).
Install the pipe (b) and tighten the clamp (a) to the torque of 1 nm +/- 10%
(sect. 3 - 3, Engine torque settings).
...
Check the idle and the co amount with warm engine
Start the engine;
Switch on the dds and check that it does not signal any error (otherwise
consult the relevant paragraph of this manual
to reset the error and proceed with the idle check);
Enter the "self diagnosis" menu by selecting the diavel model in the
available vehicle version. ...