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

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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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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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- 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
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,
Continuation
---
If displayed value is OK:
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Read Measurin
g Value Block
HELP
Input display group number XXX

Indicated on display
- Press buttons -0-, -5- and -6- to input display group number 56, and
press -Q- button to confirm input.
Read Measuring Value Block 56 1 2 3 4

Indicated on display (1-4 = display fields)
- Compare display with specified value in display field 4:

Display fields

1 2 3
4
Display group 56: Engine idle
Display xxxx RPM xxxx RPM x.xx g/s
xxxx
Indicates Actual engine
speed
(in 10 RPM
steps) Specified engine
speed
(in 10 RPM
steps) Control value-Idle mass air flow
(idle air control valve) Operating condition
Range 0-2550 RPM --- ---
---
Specified
value 0 RPM 0 RPM -1.11 to 1.11 g/s
0000 = Selector lever in P or N
0010 = Selector lever in 2/3/4/R/D

--- --- ---
If not as specified Page 24
-155
,
Continuation;
Explanation of display Page 24-
16

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