Checking rear seat heating — AUDI

Checking rear seat heating
Components involved in the rear seat heating actuation process
The activation of the rear seat heating differs according to the vehicle version and equipment.
Note
On vehicles with no
rear Climatronic operating unit
E265
, the heat setting for the rear seats is made by way of the
heated rear left seat switch with regulator
E128
or the
rear left seat heating switch
E77
and the
heated rear right seat switch with regulator
E129
or the
rear right seat heating switch
E78
. The
heated bench seat cushion for rear left seat
Z10
, the
heated backrest for rear left seat
Z11
, the
heated bench seat cushion for rear right seat
Z12
and the
heated backrest for rear right seat
Z13
are then actuated by the
heated rear seats control unit
J786
. This control unit has no self-diagnosis capability at present. Actuation is however only implemented if corresponding release is issued by the
onboard supply control unit
J519
Vehicle diagnostic tester
in
“Guided Fault Finding”
mode and
Current flow diagrams, Electrical fault finding and Fitting locations
.
On vehicles with
rear Climatronic operating unit
E265
, the rear seat heating is set via
E265
.
E265
activates the rear seat heating differently depending on the vehicle equipment and model.
On vehicles with no
control unit for rear left seat adjustment
J876
and no
control unit for rear right seat adjustment
J877
, the rear seat heating is actuated by the
rear Climatronic operating unit
E265
. The rear seat heating is then switched on by
E265
if the
onboard supply control unit
J519
does not receive any conditions preventing actuation of the seat heating.
J519
first transmits the request via the data bus to the
data bus diagnostic interface
J533
, from where it is relayed via the operating unit,
Climatronic control unit
J255
to
E265
Vehicle diagnostic tester
in the
“Guided Fault Finding”
mode and
Current flow diagrams, Electrical fault finding and Fitting locations
(for the corresponding vehicle system).
On vehicles with a
control unit for rear left seat adjustment
J876
and a
control unit for rear right seat adjustment
J877
, the rear seat heating is not actuated directly by the
rear Climatronic operating unit
E265
. Actuation is implemented by the
J876
and
J877
. The request for activation of the seat heating is transmitted by
E265
to the operating unit, (
Climatronic control unit
J255
). By way of the data bus, this control unit first relays the request to the
data bus diagnostic interface
J533
, from where it is transmitted to
J876
and
J877
Vehicle diagnostic tester
in
“Guided Fault Finding”
mode and
Current flow diagrams, Electrical fault finding and Fitting locations
(for the corresponding vehicle system).
A start/stop system is offered for this vehicle in combination with certain engines. On vehicles with a start/stop system, the seat heating is deactivated while the stop function is active (to protect the
battery
A
). However, the setting for the activation of the seat heating remains stored in the
rear Climatronic operating unit
E265
. The seat heating is switched on again after the engine has been re-started via the start function
Vehicle diagnostic tester
in
“Guided Fault Finding”
mode.
Note
The seat heating may be activated differently depending on the vehicle model
Current flow diagrams, Electrical fault finding and Fitting locations
.
Depending on the model and vehicle equipment, the various pieces of information on the actuation of the seat heating (setting transmitted by the operating and display unit (
rear Climatronic control unit
E265
), specified and actual seat temperature, etc.) are displayed differently in the various measured value blocks in the different control units
Vehicle diagnostic tester
in
“Guided Fault Finding”
mode.
Situations preventing activation of the rear seat heating (e.g. short circuit in connection to seat heating element, open circuit in power supply to corresponding control unit) are stored as faults in the
rear Climatronic operating unit
E265
, the
onboard supply control unit
J519
, the operating unit (
Climatronic control unit
J255
), the
data bus diagnostic interface
J533
, the
control unit for rear left seat adjustment
J876
or the
control unit for rear right seat adjustment
J877
(depending on the vehicle model and equipment). On this vehicle, the information that the event memory in the corresponding control unit has to be read out may not be transmitted via the data bus to
E265
Vehicle diagnostic tester
in
“Guided Fault Finding”
mode. In the event of problems with seat heating, the first step should therefore always be to read out the event memories of the control units which activate the seat heating.
Checking actuation of the heated seats is described in the Guided Fault Finding routine for the corresponding control unit (
rear Climatronic operating unit
E265
,
control unit for rear left seat adjustment
J876
or
control unit for rear right seat adjustment
J877
, depending on vehicle model and equipment)
Vehicle diagnostic tester
in
“Guided Fault Finding”
mode.
If, for example, the voltage measured at the
onboard supply control unit
J519
at terminal
“30”
drops below a value stored in
J519
, the seat heating power is reduced or the function is completely deactivated to relieve the load on the
alternator
C
Vehicle diagnostic tester
“Guided Fault Finding”
function.
The
“Read measured values”
function of the Guided Fault Finding routine for the
rear Climatronic operating unit
E265
shows which seat heating setting has been made. Actuation of the seat heating, the actual and specified temperature in the seat and the actual current flowing via the seat heating etc. are displayed in the
“Read measured values”
function of the Guided Fault Finding routine for the corresponding control unit depending on the vehicle model and equipment
Vehicle diagnostic tester
in
“Guided Fault Finding”
mode.
Depending on the vehicle model, the rear seat heating may be deactivated after a certain period if the system detects that one of the seats is not occupied (at the start of production, no provision was made for deactivation via the seat occupied sensor; introduction not yet finalised)
Owner's Manual
.