wheel AUDI A8 1995 D2 / 1.G AHA Engine Auxiliary Signals Checking Workshop Manual

24-166

- Compare display with specified values for A/C
(in display field 4).

Display fields

1 2 3 4
Display group 50: Signals to Engine Control Module (ECM)
Display xxxx RPM xxxx RPM A/C-LOW
A/C-HIGH Compr. ON
Compr. OFF
Indicates Actual engine
speed
(in 10 RPM steps) Specified engine
speed
(in 10 RPM steps) IAC boost A/C compressor status
Range 0 - 2550 RPM --- --- ---
Specified
value 620 - 740 RPM
(all-wheel drive)
or
740 - 860 RPM
(front-wheel drive) 680 RPM
(all-wheel drive)
or
800 RPM
(front-wheel drive) A/C-LOW
(all-wheel drive)
or
A/C-HIGH
(front-wheel
drive) Compressor on: Comp. ON
Compressor off: Comp. OFF

--- --- --- If not as specified page 24
-167
,
Continuation
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Continuation
If no speed was indicated:

Notes:
If the LED does not blink:
If the wiring is OK and the LED does not blink:
Repair Manual, Electrical Equipment, Repair Group 90
- Connect VAG1598/22 test box to ECM harness connector page 01
-
67
.
- Connect VAG1527B 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 Electrical Wiring Diagrams,
Troubleshooting & Component Locations binder.
-
Check readiness code page 01
-70
. If Diagnostic Trouble Code
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24-174

Rough road signal from ABS/EDL
control module, checking


Notes:

When the ABS/EDL control module senses a
wheel spinning, it produces the rough road
signal. When the ECM recognizes the rough
road signal, the misfire recognition is switched
off.
Check the rough road signal only when the
trouble code 18014 "Rough Road Spec Engine
Torque ABS-ECU Electrical Malfunction" is
stored. The possible "Misfire" malfunction is in
this case a subsequent malfunction that can be
disregarded.
The wiring and the rough road signal are
monitored by the ECM.
Emissions testing on a front-wheel drive vehicle
with ABS/EDL, during which only the front
wheels turn while the rear wheels are
stationary, can result in the DTC 18014 being
stored in DTC memory. Therefore, the fuse for
the ABS/EDL control module must be removed.
After the test, check DTC memory for the
ABS/EDL control module and the ECM. Then
erase DTC memory.
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