AUDI A8 1996 D2 / 1.G AHA Engine Throttle Valve Control Module Checking Workshop Manual

24-128


Throttle valve control module,
checking

Notes:

If the throttle valve control module -J338- is
removed and installed, or replaced, adaptation
of the throttle valve control module to the
Motronic ECM is required page 24
-150
.

Component locations page 24
-1

Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagrams
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24-129

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 VAG1551 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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malfunction in the angle sensor -1- for throttle
drive -G187-, it switches the power off for throttle
drive -G186-,and the throttle valve again
assumes the mechanical closed throttle position
(limp-home position).
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24-130

Throttle valve control module power
supply, checking


If voltage is NOT OK: - Disconnect 8-pin harness connector from throttle valve control module
-J338-.
- Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals using adapter cables from VW1594 connector test
kit.
- Switch ignition on, and check voltage. Specified values:

Connector terminals 3 and 7 (Ground): 9.0-14.5 volts
Connector terminals 4 and 7 (Ground): 4.0-6.0 volts
- Switch ignition off.
- Connect VAG1598/22 test box page 01
-67
.
- Check wiring for open circuit between ECM/test box and 8-pin harness
connector.

Connector terminal 3 to ECM/test box socket 69
Connector terminal 4 to ECM/test box socket 62
Connector terminal 7 to ECM/test box socket 67
Specified value: max. 1.5
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24-131


If wiring is OK: - 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.
- Replace Motronic Engine Control Module (ECM) -J220- page 01
-
68
.
- Carry out adaptation of throttle valve control module to ECM page
24
-150
.
- Check readiness code page 01
-70
. If Diagnostic Trouble Code
(DTC) memory has been erased, or ECM was disconnected, generate
new readiness code page 01
-73
.
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24-132

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
-130


Checking

- Connect VAG1551 or VAG1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) page 01
-8 .
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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 display group number XXX

Indicated on display
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24-133

- Press buttons -0-, -0- and -5- to input display
group number 5 (005), 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 - 12.75 ms --- ---
Specified value 620 - 740 RPM
(all-wheel drive) 1.00 - 2.50 ms 0 km/h Throttle closed: "Idle"
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740 - 860 RPM
(front-wheel drive)
Throttle slightly open: "Part throt"

--- --- --- If display is NOT OK page 24
-134
, Continuation
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24-134

Continuation

- Switch ignition off.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.

- Connect multimeter US1119 (Fluke 83 or
similar) and check resistance between test box
sockets 67 and 69.


Specified value: max. 5.0
- Open throttle slowly.


Specified value: If resistance is NOT OK:

- Disconnect 8-pin harness connector for throttle valve control module -
J338-.
- Check wiring for open circuit between ECM/test box and 8-pin harness
connector.

Connector terminal 3 to ECM/test box socket 69
Connector terminal 7 to ECM/test box socket 67
Specified value: max. 1.5
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