1995 AUDI A8 display

24-90

Voltage supply to Engine Control
Module (ECM), checking


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 diagram

Checking

- Connect VAG1551 or VAG1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with ignition
switched on) page 01
-8 .
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.
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Read Measurin
g Value Block
HELP
Input display group number XXX

Indicated on display
- Press buttons -0-, -0- and -4- to input display group number 4 (004),
and press -Q- button to confirm input.
Read Measuring Value Block 4 1 2 3 4

Indicated on display (1-4 = display fields)
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24-91

- Check battery positive voltage (B+) in display
field 2.

Display fields

1 2 3 4
Display group 4: General engine data
Display xxx RPM xx.xxx V
xxx.x C
xxx.x C
Indicates Engine speed
(in 40 RPM
steps) Battery Positive Voltage (B+)
Terminal 15 Engine coolant
temperature Intake air
temperature
Range 0 - 6800 RPM 0.000 - 16.500 V -46.5 to 141.0 -46.5 to 141.0
Specified
value 0 RPM 10.000 - 14.500 V --- ---

--- If not as specified page 24
-92
, Evaluation
of display group 4
--- ---
If displayed value is OK (as specified):

-
Press button.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.
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24-92
Evaluation of display group 4 Display group: 4


Display field: 2
Possible malfunction
cause
Corrective action
If "Control module does not answer" is
displayed
Fuse for ECM faulty- Replace fuse
Open circuit in wiring- Check voltage supply at terminal 15 page
24
-94

Displayed value changes between 10.0 -
14.5 V
Intermittent connection- Check voltage supply at terminal 15 page
24
-94

- Check voltage supply at terminal 30 page 24
-93

0.0 - 10.0 V
Battery discharged/faulty Voltage regulator faulty- Check battery
- Check generator
- Check voltage regulator
14.5 - 16.5 V Generator faultyVoltage regulator faulty- Check generator
- Check voltage regulator
Pa
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Rapid data transfer
HELP
Select function XX

Indicated on display
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24-117

- 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-, -7- and -0- to input display group number 70 (070),
and press -Q- button to confirm input.
Read Measuring Value Block 70 1 2 3 4

Indicated on display (1-4 = display fields)
Note:
During this diagnosis there should not be any load placed on the engine,
otherwise the diagnosis is interrupted and must be started again. - Press button -4- to select "Basic Setting" function 04 (diagnosis for
EVAP canister purge regulator valve is initiated).
System in Basic Setting 70 1 2 3 4

Indicated on display (1-4 display fields)
If the diagnosis is initiated by the ECM, the display changes from "Test
OFF" to "Test ON" in display field 4.
Note:
If the display changes from "Test ON" to "Test OFF" during the test,
accelerate with a brief burst to repeat the test. - Continue to run engine at idle until "EVAP OK" is indicated in display
field 4.
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24-118


Display fields

1 2 3 4
Display group 70: EVAP canister purge regulator valve
Display xxx % xx.x % xx.xx g/s Test OFF/Test
ON
EVAP OK
EVAP n.OK
Indicated EVAP canister purge regulator
valve duty cycle during diagnosis Oxygen sensor deviation
during diagnosis Idle Air Control (IAC) valve
deviation during diagnosis Diagnosis
condition
Diagnosis
results
Range 0 - 100 % -25.0 to +25.0 % -2.70 to +4.16 g/s ---
Specified
value 0 - 93 % - 15.0 to +15.0 % 1.00 - 0.00 g/s EVAP OK If "EVAP n.OK" is indicated in display field 4:

- Check for blockage or leaks page 24
-119
.
If "EVAP OK" is indicated in display field 4:

-
Press button.Rapid data transfer
HELP

Indicated on display
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24-126

Intake air system, checking for leaks


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
Engine leak detector spray G 001 800 A1

Notes:
If there are leaks, intake manifold vacuum will
draw in the leak detector spray with outside air.
The spray reduces the ability of the fuel/air
mixture to ignite, which causes a drop in engine
speed and a significant increase in CO-content.
Observe the safety precautions listed on the
container.

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 .
Rapid data transfer
HELP
Select function XX

Indicated on display
Pa
ge 163 of 166 Motronic Multi
port Fuel In
jection
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) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1