check engine AUDI A8 1995 D2 / 1.G AEB Engine Throttle Valve Control Module And Checking

24-100

Function

Idle speed stabilization is integrated in the
throttle valve control module -J338-. In the
housing opposite the throttle valve are Throttle
Position (TP) sensor -G69-, Closed Throttle
Position (CTP) switch -F60-, throttle drive -G186-
and angle sensor -1- for throttle drive -G187-.

The housing should not be opened.
The individual components cannot be replaced or
mechanically adjusted. All adjustments are
accomplished by the VAG 1551 Scan Tool (ST)
using the "Basic Setting" function 04.
If the complete throttle valve control module is
without power (i.e. disconnected), the throttle
valve assumes a mechanical closed throttle
position that results in an increased idle speed of
1200-1300 RPM (with engine at operating
temperature).
If only the Throttle Position (TP) actuator -V60- is
without power, the throttle valve also assumes a
mechanical closed throttle position (limp-home
position), but because the signal from the CTP
switch -F60- can still be recognized, a nearly
"normal" idle speed of approx. 900 RPM is
maintained with a corresponding reduction of the
ignition timing advance.
If the Engine Control Module (ECM) recognizes a
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- Check wiring for short circuit between ECM/test
box and 8-pin harness connector.


Connector terminal 7 to ECM/test box
socket 69

Connector terminal 7 to ECM/test box
socket 62

Connector terminal 4 to ECM/test box
socket 67

Specified value:

- Reconnect throttle valve control module harness
connector.
If wiring is OK:

- Replace Motronic Engine Control Module (ECM)
-J220- Page 01
-57
.

- Carry out adaptation of throttle valve control
module to ECM Page 24
-119
.

-
Check readiness code Page 01
-59
. If
Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
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24-103

Closed Throttle Position (CTP) switch,
checking


Note:
The Closed Throttle Position (CTP) switch -F60-
is inside the throttle valve control module -J338-.

Test conditions

Throttle valve in closed throttle position; if
necessary adjust accelerator pedal cable

Repair Manual, Fuel Supply System, Repair
Group 20


Cruise control adjustment OK
Power supply for throttle valve control
module OK; checking Page 24
-101


Checking

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) Page 01
-7 .
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24-104

- Press buttons -0-, -0- and -5- to input display
group number 5, and press -Q- button to confirm
input. Read Measuring Value Block 5 1 2 3 4

Indicated on display (1-4 = display fields)
- Check Closed Throttle Position (CTP) switch (display field 4):

Display fields

1 2 3 4
Display group 5: Engine electronics
Display xxx RPM xx.xx ms xxx km/h Idle
Part throt
Full throt
Decel
Enrich
Indicates Engine speed
(in 40 RPM steps) Engine Load Vehicle speed Operational condition
Range 0-6800 RPM 0.00-8.50 ms --- ---
Specified value 760-960 RPM 0.50-1.50 ms 0 km/h Throttle closed: "Idle"
Throttle slightly open: "Part throt"
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24-107

Throttle drive and angle sensor for
throttle drive, checking


Note:
Throttle drive -G186- and angle sensor -1- for
throttle drive -G187- are located in the throttle
valve control module -J338-.

Test conditions

Throttle valve in closed throttle position; if
necessary adjust accelerator pedal cable

Repair Manual, Fuel Supply System, Repair
Group 20


Cruise control adjustment OK
Power supply for throttle valve control
module OK; checking Page 24
-101


Engine coolant temperature at least 80 C
(176 F)

Automatic transmission selector lever in "P"
or "N"
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24-108

Checking

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) Page 01
-7 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
Read Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -5- and -5- to input display group number 55, and
press -Q- button to confirm input.
Read Measuring Value Block 55 1 2 3 4

Indicated on display (1-4 = display fields)
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24-109

- Compare display with specified values for idle
air control (display fields 1-4):

Display fields

1 2 3 4
Display group 55: Idle control
Display xxx RPM x.xx g/s x.xx g/s xxxx
Indicates Engine speed RPM
(in steps of 10 RPM) Regulating value-idle mass
air flow (idle air control) Learning value-idle
mass air flow Operating
conditions
Range 0-2550 RPM -2.80 to 4.17 g/s -1.94 to 2.22 g/s ---
Specified
value 820-900 RPM -1.11 to 1.11 g/s -1.11 to 1.11 g/s 0000

If engine speed is NOT OK
Page 24
-111
, Continuation
If display is NOT OK Page 24
-110
, Evaluating
display group 55
Explanation
Page 24
-110

If displayed values are OK:

-
Press button to advance program
sequence.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.

- Switch ignition off.
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24-110
Evaluating display group 55 Display group:
55


Display fields:
2 3
Possible cause
Corrective action
above 1.11
g/s
Increased load because of
switched-on consumers
Throttle valve mechanism sticking
Air passage in area of throttle
valve contaminated - Switch off electrical consumers
- Visually check, repair if necessary
below -1.11
g/s Intake air leak (false air) behind
throttle valve
Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine Mechanical,
Engine Code(s): AEB, ATW, Repair Group 26
- Check intake air system for leaks (false air) Page 24
-97
- Check exhaust system:
Explanation of the 4-digit display
Explanation when display field is = 0
x
x
x
x
(Display group 55)
0 A/C compressor off (0 = A/C compressor off /1 = A/C compressor on)
0 Shift lever in P or N (0 = Shift lever in P or N/ 1 = Shift lever in 2/3/4/R/D)
0 Always "0"
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24-113

Throttle Position (TP) sensor, checking


Note:
Throttle Position (TP) sensor -G69- is located
inside the throttle valve control module -J338-.

Test conditions

Throttle valve in closed throttle position; if
necessary adjust accelerator pedal cable

Repair Manual, Fuel Supply System, Repair
Group 20


Cruise control adjustment OK
Power supply for throttle valve control
module OK; checking Page 24
-101


Checking

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with ignition
switched; engine not running) Page 01
-7 .
Rapid data transfer
HELP

Indicated on display
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24-114

- Press buttons -0-, -0- and -3- to input display
group number 3, and press -Q- button to confirm
input. Read Measuring Value Block 3 1 2 3 4

Indicated on display (1-4 = display fields)
- Compare display with specified values for throttle angle, (display field
3):

Display fields

1 2 3 4
Display group 3: Load measurement
Display xxx RPM xx.x g/s
xxx
xx.x BTDC
Indicates Engine speed
(in 40 RPM
steps) Mass air
flow Throttle angle Ignition timing
Range 0-6800 RPM ---
0-90
0.0 -50.0
BTDC
Specified
value 0 RPM ---
0-5
0.0

--- --- If not as specified Page 24
-115
, Evaluating display
group 3
---
-
Open throttle valve slowly while monitoring degree ( ) value in display field 3. Value must increase uniformly over the entire range.
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