Introduction
The engine control system on the diavel uses a sensor that measures air temperature. This sensor has a resistance of ntc type (negative temperature coefficient), that reduces its own value when the temperature increases. The air temperature sensor allows the engine control unit to modify the fuel-air mixture and ignition advance in relation to the atmospheric air temperature.
Components assembling position
The air temperature sensor is mounted on the right hand air intake (the image also shows the location of the connection).
Wiring diagram
Ccm engine control connection, s air temperature sensor. 1 Green/blue - g/b, 2 black/purple - bk/v.
In the event of fault
In the event of an air temperature sensor fault, the engine control unit implements a recovery value of 25C.
Fault codes generated and possible correlated faults
Fault codes generated by the engine control unit and displayed by the dds (intake air temperature sensor 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 "air temperature" and the eobd warning light activates.
Possible correlated faults: inadequate engine power, irregular idle speed (target idle speed is 1350 rpm with engine stabilised at operating temperature), the engine does not start easily. Check: -sensor resistance, which must be approximately 2 kohm at 25 C.
The air temperature value may be checked using the dds. Check that the value given is plausible.
If none of the aforementioned tests identify the problem and the air temperature sensor is in proper working order, replace the engine control unit.
Component replacement methods
No special measures are necessary in order to replace the air temperature sensor.
Vehicle speed indicator
This function displays vehicle speed (km/h or mph depending on the set
measurement system).
The dashboard receives information about the actual speed and displays the
number increased by 5%.
Maximum speed displayed is 299 km/h (186 mph).
Over 299 km/h (186 mph) the display will show a s ...
Instrument panel diagnosis
This function identifies any abnormal vehicle behaviours.
The instrument panel activates any abnormal vehicle
behaviours in real time (errors).
At key-on (at the end of the check) one or more "errors"
are displayed in red (only if they are active).
When an "error" is t ...
Adjusting the chain tension
Make the rear wheel turn until you find the position where chain is tightest.
Set the vehicle on the side stand. Push down
the chain at the point of measurement and release. Measure the distance between
the "aperture" upper profile and pin
centre.
The read distance must be: 9 to 11 mm.
...