Final Control Diagnosis

Final Control Diagnosis

=> [ Activating Output Diagnostic Test Mode ]

=> [ Activated Actuators ]

Note the following as regards final control diagnosis:

• The A/C compressor regulator valve (N280) is activated by the Climatronic control module (J255) A/C control head only when the engine is not running.

• The request to activate the coolant fans (speed "1" and speed "2") is sent by the Climatronic control module (J255) A/C control head to the respective engine control module (ECM). The engine control module (ECM) switches on the fan(s) but only with the engine running. Refer to => Vehicle Diagnosis, Testing and Information System VAS 5051 in the "guided fault finding" function

• The output diagnostic test mode is possible only up to 3000 rpm and a vehicle speed of less than 3 mph (5 km/h).

• Installation locations of activated components => [ A/C System Control and Regulation Components ] A/C System Control and Regulation Components.

• Final control diagnosis can be repeated several times if necessary.

• Control element malfunctions are stored in fault memory.

• During the output diagnostic test mode, the regulation and the display of the Climatronic control module (J255) A/C control head are switched off (depending on the version, 22°C is displayed on both displays for example). The display segments in the Climatronic control module (J255) A/C control head are only actuated during the "segment test" function.

• The A/C system control motors are driven into a pre-determined position by the Climatronic control module (J255) A/C control head after selecting the "output diagnostic test mode" function. During final control diagnosis, it is therefore not necessary to wait for control motors to reach a specified position.

• In vehicles with an 8-cyl. engine, the compressor is driven by a shaft not a belt.

Activating Output Diagnostic Test Mode

- With the ignition switched off, connect the Vehicle Diagnosis, Testing and Information System (VAS 5051A) e.g. with the diagnostic cable (VAS 5051/5A) and the K-wire adapter (VAS 6017B) (or the K-wire adapter (VAS 6017A)) to the 16-pin data link connector (DLC) => [ VAS 5051A, Connecting and Selecting Functions ] VAS 5051A, Connecting and Selecting Functions.

- Switch on ignition/start engine.

• Switch ignition on (when checking activation of A/C Compressor Regulator Valve (N280), the engine should not be running)

• Start engine (to check activation of Coolant Fan ( V7))

- Set operating mode "Auto" on A/C control head Climatronic Control Module (J255).

- Select Address word "08" for A/C heater/electronics => [ VAS 5051A, Connecting and Selecting Functions ] VAS 5051A, Connecting and Selecting Functions.

- Open the instrument panel vents

- Query the DTC memory of the Climatronic control module (J255) A/C control head => [ DTC Memory, Interrogating ] DTC Memory, Interrogating.

Indication on display of Vehicle Diagnosis, Testing and Information System (VAS 5051A):

- Select function "03 - Output Diagnostic Test Mode (DTM)".

Indication on display of Vehicle Diagnosis, Testing and Information System (VAS 5051A):

• Display field - 1 - shows which actuator is currently being activated (e.g. 1st actuator in test).

• Display field - 2 - lists in succession the actuators that were already activated or which one is currently activated. The one currently being actuated appears in the bottom line.

- By touching the -> button you can call up the next component to be tested. Function and sequence => [ Activated Actuators ].

• By clicking the <- button, you will return to the selection menu.

• Output DTM can be terminated by pressing the C button.

• When output DTM is completed, check DTC memory => [ DTC Memory, Interrogating ] DTC Memory, Interrogating.

• When aborting the output diagnostic test mode, query the DTC memory => [ DTC Memory, Interrogating ] DTC Memory, Interrogating and read the measured value block (display group "002").

Activated Actuators

• The A/C compressor regulator valve (N280) is currently only activated with the engine off. If the engine is running, this actuator in the output diagnostic test mode (depending on the version of the Climatronic control module (J255) A/C control head) is not shown on the display of the Vehicle Diagnosis, Testing and Information System (VAS 5051A) and is not activated by the Climatronic control module (J255) A/C control head

• The regulator valve is installed in the compressor (the compressor can only be replaced in an A/C system service point workshop).

• The current flowing when the A/C compressor regulator valve (N280) is switched on can be measured with an inductive pickup for example.

• If there is a compression shutoff condition in addition to the compressor shutoff condition "5 = engine speed less than 300 rpm", the A/C compressor regulator valve (N280) is not activated.

CAUTION!
Do not reach into the area of the coolant fan ( V7)!

• If the activation of the coolant fan (V7) needs to be checked, start the engine. The respective engine control module switches the coolant fan(s) (V7) on only when the engine is running.

• Depending on the version of the Climatronic control module (J255) A/C control head, the coolant fan is switched on immediately in A/C system mode when the compressor is switched on or the coolant fan is only activated when a pressure of approx. 9 bar is exceeded in the refrigerant circuit.

• The request to switch on the coolant fan (V7) is transmitted via the comfort data bus system by the Climatronic control module (J255) A/C control head, to the instrument cluster control module (J285). The instrument cluster control module (J285) (gateway) then transmits the request to the powertrain data bus system to which the respective engine control module is connected. The engine control module then uses a square wave signal to activate the coolant fan control module (J293) and the coolant fan control module ( J293) activates the coolant fan(s) (V7).

• Depending on the version of the A/C control head, the Climatronic control module (J255), the coolant fan ( V7) is activated in speed "1" and "2" without further switching to a test step or further switching is necessary for activation of speed "2".

• Check the function of the interior temperature sensor fan (V42), e.g. with smoke (hold the smoke source in front of the intake frame installed in the Climatronic control module (J255) A/C control head).

• The interior temperature sensor fan (V42) is installed in the Climatronic control module (J255) A/C control head, and cannot be replaced individually.

• Depending on the version of the Climatronic control module (J255) A/C control head, the activation sequence of the back pressure flap motor (V71) and the recirculation flap motor (V113) differs (in vehicles constructed at the start of production, the back pressure flap motor (V71) is activated first, in vehicles from VIN "400000" of model year 2005 (Sedan and Avant) and "012913" of model year 2005 (Cabrio) the recirculation flap motor (V113 ) is activated first.

• This control motor is only installed in vehicles with steering on the left; it actuates the back pressure/fresh air flaps.

• This control motor is not installed in vehicles with steering on the right If this control motor is displayed in the case of a vehicle with steering on the right, check the coding of the Climatronic control module (J255) A/C control head (read measured value block, display group "019").

• The recirculation flap motor (V113) only moves the recirculation flap in vehicles with steering on the left; the back pressure/fresh air flaps are moved by the back pressure flap motor (V71).

• The recirculation flap motor (V113) moves the recirculation flap and the fresh air flaps in vehicles with steering on the right. In these vehicles no back pressure regulation is provided and no back pressure flap motor (V71) is installed.

The activation sequence of the components listed below depends on the optional equipment of the vehicle and the version of the Climatronic control module (J255) A/C control head.

• In the case of vehicles constructed at the start of production, an Climatronic control module (J255) A/C control head is installed and after the "segment test" for example the heated windshield (Z1) and then (if present as optional equipment) the heated windshield (Z2), the driver seat heating element (Z6), and the passenger seat heating element (Z8) are activated.

• For vehicles starting with VIN "400000" of model year 2005 (Sedan and Avant) and "012913" of model year 2005 (Cabrio), the driver seat heating element ( Z6) and the passenger seat heating element (Z8 ) are activated first (if present as optional equipment). The heated rear window (Z1) and (if present as optional equipment) the heated windshield (Z2) are then activated

• In the case of vehicles up to VIN "399999" of model year 2005 (in the Sedan and Avant) and "012912" of model year 2005 (Cabrio), the heated rear window ( Z1) is directly controlled by the Climatronic control module (J255) A/C control head (the relay that connects the current is installed in the Climatronic control module (J255) A/C control head)

• In the case of vehicles up to VIN "400000" of model year 2005 (in the Sedan and Avant) and "012913" of model year 2005 (Cabrio), the heated rear window ( Z1) is no longer directly controlled by the Climatronic control module (J255) A/C control head (a relay is not installed in the Climatronic control module (J255) A/C control head with a part number from index "AJ"). In these vehicles the heated rear window (Z1) is controlled via the rear window defogger relay (J9).

• The switch-on function of the Climatronic control module (J255) A/C control head for the heated rear window (Z1) can be checked for example in vehicles up to VIN " 399999" of model year 2005 (Sedan and Avant) and "012912" of model year 2005 (Cabrio) during the output diagnostic test mode with the multimeter (V.A.G 1715 ). Place the inductive pickup over the positive wire from the Climatronic control module (J255) A/C control head to the heated rear window (Z1) and select the "current measurement via inductive pickup" function on the multimeter; the display changes from approx. 0 A to greater than 7 A.

• If the "heated windshield" actuator is displayed in vehicles without that option after the heated rear window (Z1) actuator, check the coding of the Climatronic control module A/C control head (J255). Refer to => [ A/C Control Head Climatronic Control Module, Coding ] A/C Control Head Climatronic Control Module, Coding.

• If this actuator is activated in vehicles without the "heated windshield" option, check the coding of the Climatronic control module (J255) A/C control head => [ A/C Control Head Climatronic Control Module, Coding ] A/C Control Head Climatronic Control Module, Coding.

• The heated windshield (Z2) is activated by the Climatronic control module (J255) A/C control head in the output diagnostic test mode only up to a temperature of approx. 40° C in the passenger compartment. If the temperature is higher, " function unknown or currently cannot be executed" is shown on the display of the fault read-out device.

• The switch-on function of the heated windshield control module (J505) can be checked with the multimeter (V.A.G 1715) for example. Place the inductive pickup over the positive wire from the heated windshield control module (J505) to the heated windshield (Z2) and select the "current measurement via inductive pickup" function on the multimeter (V.A.G 1715); the display changes from approx. 0 A to greater than 7 A.

• The function of the heated windshield (Z2) is displayed in the measured value block of the Climatronic control module (J255) A/C control head (display group "015 ") and => [ Heated Windshield ] Heated Windshield.

• The heated seats are only activated in the case of a Climatronic control module (J255) A/C control head equipped with a potentiometer for seat heating (observe part no. and index).

• The switch-on function for seat heating can be checked with the multimeter (V.A.G 1715) for example. Place the inductive pickup over the positive wire to the seat heating element and select the "current measurement via inductive pickup" function on the multimeter (V.A.G 1715); the display changes from approx. 0 A to greater than 2 A.

• The "seat ventilation" option is currently not available (introduction not yet finalized).

• Climatronic control module (J255) A/C control heads configured for activation of seat ventilation can be identified by the part no. and by the thumb wheels for seat heating (position " 0" is in the center of the adjusting range)