1998 AUDI A8 AEB Engine Additional Signal

The speed signal is generated by the vehicle
speed sensor (at the transmission), and
processed at the speedometer/odometer in the
instrument cluster.
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Test procedure

- 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-, -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)
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- Road test and compare indicated vehicle speed
with value in display field 3 (2nd technician
required).

Display fields

1 2 3 4
Display group 5: Engine Electronics
Display xxx RPM xx.xx ms xxx kph Idle
Part throt
Full throt
Decel
Enrich
Indicates Engine speed
(in 40 RPM
steps) Engine
load Vehicle speed Operating
condition
Range 0-6800 RPM --- --- ---
Specified
value --- --- Approx. vehicle speed ---

--- --- If no vehicle speed is displayed Page 24
-152
,
Continuation
---
If displayed value is OK:
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-
Press button toadvance program sequence.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.

- Switch off ignition.
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Continuation
If no speed was indicated:

Notes:
If the LED does not blink:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
If the wiring is OK and the LED does not blink:
Repair Manual, Electrical Equipment, Repair Group 90
- Connect VAG 1598/22 test box to ECM harness connector Page 01
-
56
.
- Connect VAG 1527B LED voltage tester between ECM/test box
sockets 3 (B+) and 20 (signal).
- Lift vehicle at left front until wheel is free.
- Switch ignition on and rotate left-front wheel by hand.
LED must blink (very brief blink)
The right-front wheel must not rotate; block it if necessary.For LEDs with little voltage consumption, the LED lights up at half
strength when the ignition is switched on.
- Check wiring from ECM connector, terminal 20 to instrument cluster for
open circuit or short circuit
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- Check readiness code Page 01
-59
. If DTC memory was erased, or
ECM disconnected, generate new readiness code Page 01
-62

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Transmission Range (TR) signal,
checking


Notes:

Through the multi-function Transmission Range
(TR) program switch -F125- at the transmission,
the Engine Control Module (ECM) recognizes
whether a drive range is selected (selector lever
in 2/3/4/R/D) or not (selector lever in P or N)
The multi-function Transmission Range (TR)
program switch -F125- at the transmission
switches to Ground through terminal 22 of the
ECM when the shift lever is in N or P.
When a drive range is selected, the switch
opens and terminal 22 now has power.

Required special tools and test equipment
VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable
VAG 1598/22 test box

Test procedure

-
Connect VAG 1551 or VAG 1552 scan tool and
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yp
e=re
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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.
Pa
ge 16 of 29 Additional si
gnals
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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.5