AUDI A6 1996 C5 / 2.G 01V Transmission OBD Functions Workshop Manual

01-1


On Board Diagnostic (OBD),
function
The automatic transmission is controlled electro-
hydraulically.
The automatic Transmission Control Module
(TMC) -J217- receives information from
components that effect the selection of gears. It
passes the information on to solenoid valves that
control the solenoid valves in the valve body. The
solenoid valves convey the fluid pressure
generated by the ATF pump to the appropriate
clutches and brakes to be engaged.

Transmission Control Module (TMC) -J217-
malfunction recognition
The term "On Board Diagnostic (OBD)" applies
specifically to the electronic/electric control.
The control module is equipped with a Diagnostic
Trouble Code (DTC) memory so in the event of
an electronic/electrical component failure or on
open circuit, the malfunction can be determined
quickly. Malfunctions are recognized by electrical
signals and stored in the DTC memory together
with an indication of the type of malfunction and
malfunction location.
The control module recognizes malfunctions
during vehicle operation and stores them in a
DTC memory. This information will remain
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available even if the system voltage fails.
The control module distinguishes between
permanent malfunctions that have occurred and
sporadic malfunctions.
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01-2
If a malfunction is no longer present after a
certain time or a long drive, it will be converted to
a sporadic (SP) DTC.
A malfunction will also be converted to sporadic
when the DTC memory is not erased after
repairs.
Malfunctions which are stored in the memory as
sporadic malfunctions, will be displayed as
"sporadic DTCs" when checked by the scan tool
V.A.G 1551. In such cases "SP" appears on the
right of the display. If the printer is switched on,
the print-out will show "sporadic DTC" after the
identification of the malfunction.
If the sporadic DTC does not occur again after 40
cold engine starts and subsequent transmission
warm-up, the malfunction in DTC memory will be
automatically erased.
The possibilities offered by On Board Diagnostic
can only be used with the Vehicle Diagnostic,
Testing and Information System VAS 5051 or the
V.A.G 1551 scan tool (mode 1, rapid data
transfer).
Available functions of Vehicle Diagnostic, Testing
and Information System VAS 5051 or the
V.A.G1551 scan tool page 01
-42
.
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01-3

Security functions of the Transmission
Control Module (TCM)
When one or more components or sensors fail,
the Transmission Control Module (TCM) -J217-
activates the appropriate alternate functions or
emergency programs. This ensures destruction-
free operation of the automatic transmission with
some effect on the function and quality of
shifting.
When critical malfunctions occur with an active
TCM, the current selected gear will be held.
"Mechanical emergency running mode with the
control module active" is activated by the TCM as
soon as the driving situation regarding
transmission security and engine security permits
it.

Mechanical backup with active control
module

- The transmission shifts out of all forward gears
into hydraulic 4th gear. The torque converter
clutch is unlocked (not applied). All solenoid
valves are de-energized.

- Maximum shift pressure is applied to the power-
transmitting elements.

-
Reverse gear can be engaged. The shift lock
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solenoid is active (in "P" and "N").

- All segments of the transmission range selector lever display light up.
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01-4

- The Multi-function Indicator Light (MIL) lights up
after 2 driving cycles (Dcy); check DTC memory
( page 01
-43
and compare with DTC table
page 01
-45
).
If the TCM -J217- malfunctions (e.g. if the power
supply is faulty or the connector becomes
disconnected), the transmission will immediately
switch to "mechanical back-up mode with
inactive control module" and continue to
operate.

Mechanical backup with non-active control
module

- The transmission shifts out of all forward gears
into hydraulic 4th gear. The torque converter
clutch is unlocked (not applied). All solenoid
valves are de-energized.

- Maximum shift pressure is applied to the power-
transmitting elements.

- Reverse gear can be engaged. The shift lock
solenoid is active (in "P" and "N").

- All of the segments transmission range selector lever display are dark.
-
The MIL lights up when the Engine Control Module (ECM) has
recognized a CAN-bus malfunction (missing data exchange between
engine and transmission control modules) (after 2 Dcy); check DTC
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memory of the control module.
- Transmission Control Module (TCM) -J217- does not function at all, i.e.
it cannot be checked via On Board Diagnostic (OBD).
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01-5

Malfunction Indicator Lamp (MIL)
function, checking

If emissions malfunctions are recognized by the
TCM, the Malfunction Indicator Lamp (MIL) will
be switched on.

Location of the MIL: integrated in speedometer in instrument cluster
Notes:
When the MIL is switched on, it will either blink or light continuously. The
DTC memory for the TCM must be checked page 01
-43
.
MIL flashing: there is a malfunction that could damage the Three Way
Catalytic Converter (TWC). In this case, drive only with reduced
power. MIL continuously on: there is a malfunction that degrades emissions.
Check DTC memory of the Engine Control Module (ECM) or the TCM. If there are driveability problems (e.g. a customer complaint) and the
MIL is not on, perform the MIL functional because malfunctions can be
stored that do not switch the MIL on.
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01-6

MIL functional check

- Switch ignition on: MIL must come on.

If the MIL does not come on when the ignition is
switched on (with the engine not running):
Check DTC memory page 01
-43
. If
necessary, check wiring per wiring diagram or
replace light bulb.

- Start engine and let idle: MIL must switch off
after several seconds.

If the MIL does not switch off after the engine is
started: Check DTC memory page 01
-43
.
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01-7

Conditions for recognition of a driving
cycle (Dcy)

A driving cycle (Dcy) is complete when the
ignition is switched on one time, the engine
starts, the engine start is recognized by the
control module, and the ignition is switched off.
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