1998 AUDI A8 ignition

24-134


Electronic engine power
control (E-Gas), checking

E-Gas system, function

For E-Gas, the throttle valve is not operated by a
cable from the accelerator pedal. There is no
mechanical connection between the accelerator
pedal and the throttle valve.
The position of the accelerator pedal is
communicated to the Engine Control Module
(ECM) via two sensors for accelerator pedal
position (variable resistances; stored in one
housing) that are connected with the accelerator
pedal.
The accelerator pedal position (driver's intention)
is a main input unit for the ECM.
Operation of the throttle valve occurs via an
electric motor (throttle valve actuator) in the
throttle valve control module. This is true across
the entire engine speed and engine load
spectrum.
The throttle valve is operated by the throttle valve
actuator according to the instructions of the
ECM.
With ignition switched on and engine off, the
ECM activates the throttle valve actuator
precisely according to the sensor for accelerator
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24-136

Electronic Power Control (EPC) warning
lamp -K132- in instrument cluster,
significance

"EPC" is an abbreviation and stands for
Electronic Power Control (E-gas).

Installation location of EPC warning lamp
Engine Control Module (ECM) checks all components that are important
for function of the E-Gas system after ignition is switched on.
The Engine Control Module (ECM) switches on the EPC warning lamp
after ignition is switched on. Shortly after engine is started, the EPC
warning lamp will go out. This requires, first of all, that the Engine Control
Module (ECM) does not detect a malfunction in the E-gas system and,
secondly, that activation of the lamp by the Engine Control Module (ECM)
is OK.
If malfunctions are recognized in the E-Gas system during operation of
the engine, the ECM switches on the EPC warning lamp in instrument
cluster. (These malfunctions are listed in the DTC table). An entry is made
in DTC memory at the same time.
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24-138

Function test of warning lamp

- Switch ignition on.


Engine Control Module (ECM) switches EPC
lamp on.

- Start engine.

Shortly after engine is started, the EPC
warning lamp will go out if there are not
malfunctions stored in DTC memory that
relate to the E-gas system

A- Fault light for power accelerator activation
-K132- does not light up

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-17
.

- Bridge sockets 1 and 48 of test box.

- Switch ignition on.


Warning lamp must light up.
If warning lamp does not light up:
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- Switch ignition off.

- Remove instrument cluster:

Repair Manual, Electrical Equipment, Repair
Group 90, Instrument cluster, removing and installing

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24-142

Throttle valve control module, adapting

The adaptation teaches the Engine Control
Module (ECM) various positions of the throttle
valve when the ignition is on and the engine is
stopped. These positions are stored in the
control module The return communication
regarding the position of the throttle valve occurs
via the two angle sensors for throttle drive.
An adaptation must always be performed when
the throttle valve control module -J338- or the
Engine Control Module (ECM) are removed and
installed (or replaced) or if voltage supply to the
Engine Control Module (ECM) is interrupted.
The learning process (adaptation) occurs:

automatically if the ignition is switched on for at
least 10 seconds without operating starter and
accelerator pedal and the Engine Control
Module (ECM) recognizes "adaptation
required". (There will be no notification of
whether adaptation was successful or not
however). Adaptation required is recognized if
stored voltage values from the angle sensors
do not match actual measured voltage values
within a certain tolerance range.
via initiation of basic setting (function 04)
display group 060 with ignition on.
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24-143

Note:
Engine will not start during automatic adaptation.

Special Tools and Equipment

Requirements
VAS5051 with VAG5051/1
orVAG1551 with VAG1551/3BNo DTCs in DTC memory, check DTC memory Page 01
-15
.
Engine not running, ignition switched on. Accelerator pedal not depressed. Coolant temperature 10 to 95 C. Intake air temperature 10 to 90 C. Supply voltage for ECM larger than 12.7 V; checking Page 28
-30
.
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24-144

Procedure

- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .

Ignition must remain switched on for this.Rapid data transfer
HELP
Select function XX

When indicated on display:
- Press buttons -0- and -4- to select "Initiate basic setting" and press -Q-
button to confirm input.
Basic Settin
g
Q
Input display group number XXX

When indicated on display:
After pressing Q-button, throttle valve actuator will be switched on without
current.
In this condition, the throttle valve will be drawn into an emergency
position by a mechanical spring, which is located in the throttle valve
control module. The values supplied by the two angle sensors in this
emergency position are stored by the Engine Control Module (ECM). - Press buttons -0-, -6- and -0- to select "display group number 060" and
press -Q- button to confirm input.
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24-147

Note:
The control module can abort adaptation for the
following reasons:

Throttle valve cannot be closed completely (e.g.
contamination)
Battery voltage is too low.
Throttle valve control module or wire connection
is faulty.
Engine is started during adaptation or
accelerator pedal is operated.
Tension of throttle valve housing (check
bolts)
After termination, tester displays "Function is
unknown or cannot be performed at the
moment". The next time the ignition is switched
on (several seconds), adaptation will be
automatically repeated.

- End basic adjustment of the engine by pressing
the key.
Rapid data transfer
HELP

Indicated on display (function selection):
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