wiring AUDI A8 1999 D2 / 1.G AEB Engine Additional Signal

24-145


Additional signals

Signal from A/C compressor, checking


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
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit
Wiring diagrams

Test conditions
A/C functions OK
A/C is switched off
Vehicle at room temperature-above 15 C
(59 F)

No malfunctions stored in Diagnostic Trouble
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Continuation
If the displayed values are NOT OK:

- Connect VAG 1598/22 test box to ECM harness
connector Page 01
-56
.

- Check wiring for open circuit, short circuit to B+
or short circuit to Ground between ECM/test box
terminal 8 and A/C control head -E87-, or
Transmission Control Module (TCM).

Electrical Wiring Diagrams, Troubleshooting &
Component Locations If the wiring is OK:

- Check function of A/C control head -E87-.

Repair Manual, Heating & Air Conditioning,
Repair Group 01

Or:

Repair Manual, 5 Spd. Automatic
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24-149

Vehicle speed signal, checking


Required special tools and test equipment

VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit
Wiring diagrams

Test conditions
Vehicle Speed Sensor (VSS) OK; checking:

Repair Manual, Electrical Equipment, Repair
Group 90


Notes:

To check Vehicle Speed Sensor -G68-, the
vehicle must be driven. A second technician is
required to operate the scan tool during the
road test.
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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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If the LED lights up continuously or does not light
up at all:

- Check wiring for open circuit, short circuit to Ground or short circuit to
B+ between ECM/test box socket 22 and multi-function Transmission
Range (TR) program switch -F125-.
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24-156
If the wiring is OK:

- Check multi-function Transmission Range (TR)
program switch -F125-.

Repair Manual, 5 Spd. Automatic
Transmission 01V, Repair Group 01


- Check readiness code Page 01
-59
. If
Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
generate new readiness code Page 01
-62
.
Explanation of 4-digit display
Explanation when display field is = 0
x
x
x
x
(Display group 56)
0 A/C compressor off (0 = A/C compressor off / 1 = A/C compressor on)
0 Selector lever in P or N (0 = selector lever in P or N /1 = selector lever in 2/3/4/R/D)
0 Always "0"
0 Always "0"
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Continuation

Note:
The wiring to the Transmission Control Module is
monitored by On Board Diagnostic and stores
the Diagnostic Trouble Code 00545 if there is a
malfunction.
If displayed value is NOT OK (not as specified),
or if DTC 00545 is stored in DTC memory:

- Connect VAG 1598/22 test box to ECM harness
connector Page 01
-56
.

Electrical Wiring Diagrams, Troubleshooting & Component Locations - Check wiring for short circuit or open circuit between ECM harness
connector terminal 23 and to Transmission Control Module (TCM),
according to wiring diagram
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24-161

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 "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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Test requirements

ECM coding OK Page 01
-13


Test sequence

- Switch ignition off.

- Connect VAG 1598/22 test box to ECM harness
connector Page 01
-56
.

- Check signal wiring for short circuit or open
circuit between ECM/test box and ABS control
module, according to wiring diagram.
If the wiring is OK:

- Replace ABS control module.
If the malfunction occurs again after the ABS
control module has been replaced:

- Replace Motronic 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
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