ignition AUDI A4 1998 B5 / 1.G AC System On Board Diagnostic Workshop Manual

01-2

Notes:

This Repair Manual describes On Board
Diagnostic (OBD) with VAG1551 Scan Tool
(ST). OBD procedures can also be performed
with VAG1552 Scan Tool (ST) (VAG1552 Scan
Tool is not equipped with a printer).
Scan Tool VAG1551 or 1552 must be used in in
operating mode -1- (Rapid data transfer).
Operating mode -2- (Flash code output) is not
provided for A/C and Heating OBD.
Always check DTC memory and perform
necessary repairs before erasing DTC memory.
DTC output is possible only if ignition is on or
engine is running and engine speed is less than
3000 rpm (if engine speed is higher, output is
possible only for a limited time or is terminated).
If a fault exists for a certain time it is stored as a
static fault.
If a static fault is no longer present after a
certain time, it is stored as a sporadic fault and
the reference "SP" appears on the upper right
of the VAG1551 display/print-out.
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01-3

Notes:

A/C system component locations: engine
compartment page 87
-96
.

A/C system component locations: passenger
compartment page 87
-106
.

If a the display of a newly installed A/C control
head -E87- flashes after switching the ignition
on (for approximately 2 minutes), code the
control head page 01
-57
and execute basic
setting page 01
-52
.

If a replacement control head is not coded after
installation or if an unrecognized code was
entered, code "00042" (4-cyl. gasoline engine
USA) is stored.
Control of A/C compressor, flap motors and fan
motors etc. is not possible when executing
Output Diagnostic Test Mode (DTM), function
03 and basic setting, function 04. A/C control is
possible in all other functions.
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01-5

Notes:

For m.y. 1997, changes that affect monitoring of
the A/C system by A/C control head -E87- were
made.
Monitored components, locations pages 87
-
101
and Page 87
-113
.

Additional technical data and notes page 01
-
1 .

If a replacement A/C control head is not coded
after installation or if an unrecognized code was
entered, code "04142" (Audi A4 -4cyl. -USA) is
stored.
The A/C control head is no longer connected to
terminal 30 (vehicle electronics). The last input
setting (into the A/C control head) is stored
when the ignition is switched off and retained
when the ignition is switched on.
The duration of time when ignition is off is
calculated by the A/C control head. When
ignition is switched on, the previous "standing
time" is calculated by monitoring a time signal
from the instrument cluster. If more than 4
hours pass since ignition was switched off, the
actual measured values of the outside
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01-9


- With ignition switched off, connect VAG1551 Scan Tool (ST) to Data
Link Connector (DLC) with cable VAG1551/3.
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01-10

1997 vehicles

All vehicles - With ignition switched off, connect VAG1551 (VAG1552) scan tool to
16-pin Data Link Connector (DLC) under dash to left of steering
column, using adapter cable VAG1551/3.
V.A.G - ON BOARD DIAGNOSTIC HELP1 - Rapid data transfer2 - Blink code output

Indicated on display 1) 1) Operating modes 1 and 2 are displayed alternately
- Switch on printer with -PRINT- button (indicator lamp in switch will light
up).
- Switch on ignition or start engine.
- Switch A/C compressor on (press "AUTO" button).
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01-19

If DTC are displayed:

- Refer to DTC table and check and repair as
instructed page 01
-22
.

- Operate A/C system and check DTC memory
(function 02) to confirm repair.

- Erase DTC memory (function 05).

- Confirm A/C control head -E87- coding (function
01), and if necessary code -E87- (function 07).

- Perform basic setting (function 04).

- Check DTC memory (function 02), if
malfunctions are stored, erase DTC memory
(function 05).

- VAG1551 Scan Tool (ST) can be returned to the
function mode by pressing the button. Rapid data transfer
HELP
Select function XX

Indicated on display (function selection)
- End output (function 06) page 01
-56
.
- Switch ignition off and disconnect VAG1551 Scan Tool (ST) from Data
Link Connector (DLC).
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01-20

If no DTC are displayed and A/C system
complaints exist (e.g. compressor does not
run or only occasionally, system control
unsatisfactory, speed of fresh air blower
cannot be regulated etc.):

- Read measuring value block (function 08).

- Perform Output Diagnostic Test Mode (DTM)
(function 03).

- Check A/C system cooling performance page
87
-213
.

- VAG1551 Scan Tool (ST) can be returned to the
function mode by pressing the button. Rapid data transfer
HELP
Select function XX

Indicated on display (function selection)
- End output (function 06) page 01
-56
.
- Switch ignition off and disconnect VAG1551 Scan Tool (ST) from Data
Link Connector (DLC).
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01-21

Notes:

1997 If A/C control head -E87- is unable to
determine the duration of time when ignition is
off ("standing time"), DTC 01206 "signal for time
span ignition off" is loaded into memory. The
A/C control head will then default to a standing
time greater than 4 hours. The actual measured
values of the outside temperature sensor are
then used as instantaneous outside and engine
temperature inputs for A/C system control.
When the "heating" mode is selected under
these conditions, fresh air blower -V2- has a
delayed start (even when the actual standing
time is less than 4 hours and the engine is
warm) page 01
-86
, Read Measuring Value
Block. The outside air temperature display -
G106- may also indicate incorrect outside
temperature values.

If both display fields of the A/C control head do
not light with ignition switched on check control
head coding Page 01
-57
.
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02). After repair, erase DTC memory and end output (functions 05 and 06).
Use VAG1598 Test Box with cables VAG1598/11 and VAG1598/12 when testing DTC related wiring/connections to A/C
control head -E87- and always refer to current wiring diagram.
If A/C control head -E87- continues to operate after ignition is switched off, check wiring to -E87- terminal -D1- for short
circuit to positive using wiring diagram.
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01-23
Notes

If 22 C (72 F) is always displayed after switching ignition off and on, regardless of last setting, check power supply
(terminal 30) to A/C control head -E87- using wiring diagram. If a malfunction is recognized at an air/temperature distribution flap motor potentiometer, air distribution can be altered by
pressing buttons on A/C control head -E87-.
To switch display from C (Celsius) to F (Fahrenheit)(and vice versa), press "Temperature +" button while holding
"recirculating air" button. If no DTC are displayed and air conditioning system complaints exist (e.g. compressor does not run or only occasionally,
system control unsatisfactory, speed of fresh air blower cannot be regulated etc.), perform function 03 "Output Diagnostic
Test Mode (DTM)" and 08 "Read Measuring Value block."
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e=re
pair&id=AUDI.B5.HA01.01.1