Checking activation of electric auxiliary air heater — AUDI

Checking activation of electric auxiliary air heater
Note
Different versions of heater unit (e.g. different heat exchanger and seals) and of heater control unit
J65
(e.g. differences in pin assignment and function of
J65
) depending on production period and vehicle identification number
Chapter
,
Chapter
and
Electronic parts catalogue
No self-diagnosis and
“Guided Fault Finding”
capability is provided for the
heater control unit
J65
with part number
“8X0 819 045”
. The request for activation of the supplementary heater is transmitted to the corresponding engine control unit via a special output
Current flow diagrams, Electrical fault finding and Fitting locations
.
Self-diagnosis is possible for the
heater control unit
J65
with part number
“8XA 819 045”
Vehicle diagnostic tester
,
“Guided Fault Finding”
. The request for activation of the supplementary heater is transmitted to the corresponding engine control unit via signal wires
Current flow diagrams, Electrical fault finding and Fitting locations
.
Installed on vehicles with TDI engine and certain petrol engines from model year 2012 onwards (gradual introduction)
Special tools and workshop equipment required
Vehicle diagnostic tester
Test box, 105-pin
V.A.G 1598/42-1
and
test adapter
V.A.G 1598/47
Note
Heat energy is supplied to the air after leaving the heat exchanger when there is a request from the heater controls (
heater control unit
J65
) in the engine control unit.
The activation of the electric auxiliary air heater is checked in 3 stages; the checking procedure is described for the corresponding engine control unit in the
“Guided Fault Finding”
function
Vehicle diagnostic tester
.
On vehicles with a start/stop system, the
auxiliary air heater element
Z35
is deactivated while the stop function is active (to protect the battery).
The
auxiliary air heater element
Z35
is activated again after the engine has been re-started by the automatic start function
Vehicle diagnostic tester
,
“Guided Fault Finding”
.
Checking activation signal from heater controls with
heater control unit
J65
A switch is fitted in the
heater control unit
J65
. This switch is activated (closed) via the rotary temperature control
1
in the range between approx. 3 o'clock and the
“warm”
stop position.
When the supplementary heater switch is closed and the ignition is on, the electronics in the
heater control unit
J65
(version with part number
“8X0 819 045”
) switch an earth input through to the corresponding engine control unit via contact
“7”
. The heater control unit
J65
with part number
“8XA 819 045”
transmits the request for activation to control unit via the data bus. The engine control unit detects that additional heating output is required and switches on the
auxiliary air heater element
Z35
via the
low heat output relay
J359
and the
high heat output relay
J360
if the other cut-in criteria required for activation are also met
Current flow diagrams, Electrical fault finding and Fitting locations
and
Vehicle diagnostic tester
,
“Guided Fault Finding”
mode for engine.
Note
From model year 2012 onwards,
Z35
is also installed on vehicles with certain petrol engines (gradual introduction). The correct version of the engine control unit must be installed so that it can activate
Z35
(via
J359
and
J360
)
Vehicle diagnostic tester
and
Electronic parts catalogue
.
Cut-in criteria for electric auxiliary air heater, activation of
auxiliary air heater element
Z35
by engine control unit
Vehicle diagnostic tester
,
“Guided Fault Finding”
function for engine.
Note
Certain criteria must be met in the corresponding engine control unit for the engine control unit to activate the 3-stage
auxiliary air heater element
Z35
via the
low heat output relay
J359
and the
high heat output relay
J360
Vehicle diagnostic tester
,
“Guided Fault Finding”
function for engine.