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

Before replacing a suspected malfunctioning
component, check all related wiring,
connections, harness connectors and Ground
(GND) connections according to the appropriate
wiring diagram.
Output Diagnostic Test Mode (DTM), Basic
Setting, A/C control head identification and
coding functions are also possible.
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01-11

- Press button -1- for operating mode "Rapid data
transfer." Rapid data transfer
HELP
Enter address word XX

Indicated on display
Notes:
If display is blank, check wiring to VAG1551/power supply using
Troubleshooting Procedure No. 1 in "Electrical Wiring Diagrams,
Troubleshooting and Component Locations" Manual.
Address word for A/C Heating Electronics: 08
Additional operating instructions can be obtained by pressing the
HELP button on VAG1551 Scan Tool (ST) During testing procedures, the button advances the program to the
next step An incorrect entry can be cancelled with the -C- button
- Press buttons -0- and -8-.
Rapid data transfer
Q
08 - A/C Heating Electronics

Indicated on display
- Press -Q- button to confirm input.
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01-12
If one of the following messages is displayed: Rapid data transfer
HELP
Control module does not answer

Indicated on display
or
Rapid data transfer
HELP
K wire not switchin
g to B+

Indicated on display
- Press HELP button to print out list of possible causes.
Rapid data transfer No si
gnal from control module

- Check wiring to Data Link Connector (DLC) according to wiring
diagram Electrical Wiring Diagrams, Troubleshooting & Component
Locations binder.
Rapid data transfer Error in communication link

If this display appears at the beginning of or during the OBD program,
malfunctions have occurred and data transfer is no longer possible
between the VAG1551 Scan Tool (ST) and the A/C control head -E87-.
Electrical Wiring Diagrams, Troubleshooting & Component Locations
binder - Check wiring to DLC.
Rapid data transfer
Q
08 - A/C Heatin
g Electronics

- After repairing possible causes of the malfunction, press buttons -0-
and -8- to insert "AC/Heating Electronics" address word 08.
- Press -Q- button to confirm input.
Rapid data transfer Scan Tool sends address word 08

Indicated on display
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01-22
Diagnostic Trouble Code (DTC) table

Notes:

DTC changes affecting m.y. 1997 vehicles page 01
-38
.
Diagnostic Trouble Codes (DTC) recognized by A/C control head -E87- and displayed on VAG1551 Scan Tool (ST)
starting on page 01
-24
.
If malfunctions occur only occasionally or if the DTC memory was not erased after repairs, such DTC are displayed as
"sporadic faults." (The contents of DTC memory is retained until erased, "permanent memory").
DTCs and flash codes (only for specific components) appear only in the printout in operating mode -1-, (Rapid data
transfer).
In addition to displayed DTC and affected component descriptions, malfunction cause information is listed in the table
below the DTC code.
After performing repairs and operating the A/C system, DTC memory must always be checked again to confirm the repair.
Before replacing a suspected malfunctioning component, check all appropriate wiring, connections, harness connectors
and Ground (GND) connections.
When checking for the cause of sporadic faults, check all plug connections and wiring between A/C control head -E87-
and any component recognized as being inoperative using wiring diagram.
After replacing AC/heating system components, always perform basic setting (function 04), check DTC memory (function
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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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01-24

VAG1551 scan tool
display Possible cause
Corrective action
00000
No DTC recognized If "no DTC recognized appears after performing repairs, OBD is ended.
00529 2122
Speed information
missing /SP1) - Open circuit in wiring between Engine Control Module
(ECM), instrument cluster and A/C control head -E87-
- ECM and instrument cluster supply an unusable engine
speed signal - Diagnose and repair open circuit in
wiring using wiring diagram
- Read measuring value block
page 01
-63

- Test engine speed signal
Repair Manual, Fuel Injection &
Ignition, Repair Group 24
00532 2234
Supply voltage

Signal too low /SP - Voltage drops in electrical system to levels of less than
9.5 V2)
- Contact resistance in cable connection to A/C
Refrigerant Low Pressure Switch -F73- - Test Generator (GEN) and Voltage
Regulator (VR)
Repair Manual, Engine
Mechanical, Repair Group 27
- Diagnose and repair contact
resistance using wiring diagram
1)This fault may be generated during Output Diagnostic Test Mode (DTM) (no engine speed signal recognized although A/C
compressor speed detected).
2) If voltage at -E87-connector -C3- drops below 9.5 V, compressor switches off for a minimum of 25 seconds. Compressor
switches on again when voltage exceeds 10.8 V.
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01-25

VAG1551 scan tool display
Possible cause
Corrective action
00600
Temperature Regulator Flap Motor
Position Sensor -G92- for
Temperature Regulator Flap Motor
V681)
Short circuit to ground /SP

Open circuit/short circuit to
positive /SP
Adaptation limit exceeded
Mechanical malfunction. - Short circuit, open circuit in wiring or
incorrect terminal assignment (wires
interchanged) of connectors between -G92-
and -E87-
- Temperature flap not operating freely
- -G92- in -V68- inoperative- Diagnose and repair short circuit,
open circuit in wiring or confirm
terminal assignment using wiring
diagram

- Check for free operation of
temperature flap
- Replace -V68-
00601
Central Flap Motor Position Sensor
G112 in Central Air Flap Motor V70
Short circuit to ground /SP

Open circuit/short circuit to
positive /SP
Adaptation limit exceeded2)
Mechanical malfunction - Short circuit, open circuit in wiring or
incorrect terminal assignment (wires
interchanged) of connectors between -
G112- and -E87-
- Central flap not operating freely
- -G112- in V70 inoperative- Diagnose and repair short circuit,
open circuit in wiring or confirm
terminal assignment using wiring
diagram

- Check for free operation of central
flap3)
- Replace -V70-
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01-26

VAG1551 scan tool display
Possible cause
Corrective action
00602
Footwell/Defrost Flap Motor
Position Sensor G114 in
Footwell/Defroster Flap Motor V85
Short circuit to ground /SP

Open circuit/short circuit to
positive /SP

Adaptation limit exceeded1)

Inoperative - Short circuit, open circuit in wiring or
incorrect terminal assignment (wires
interchanged) of connectors between -G114-
and -E87-
- Footwell/defroster flap not operating freely
- -G114- in -V85- inoperative- Diagnose and repair short circuit,
open circuit in wiring or confirm
terminal assignment using wiring
diagram

- Check for free operation of
footwell/defroster flap2)
- Replace -V85-
00603
Footwell/Defroster Flap Motor V85

Blocks or de-energized /SP - Short circuit, open circuit in wiring or
incorrect terminal assignment (wires
interchanged) of connectors between V85
and -E87-
- Footwell/defroster flap flap not operating
freely
- -V85- inoperative- Diagnose and repair short circuit,
open circuit in wiring or confirm
terminal assignment using wiring
diagram

- Check for free operation of
footwell/defroster flap
- Check -V85- using function 03
(Output DTM) page 01
-42

1)This fault only recognized during basic setting.
2) Both end stops must be reached.
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01-27

VAG1551 scan tool
display Possible cause
Corrective action
00604
Back Pressure Flap
Motor Position Sensor
G113 in Air Flow Flap
Motor V71

Short circuit to
ground /SP

Open circuit/short
circuit to positive /SP

Adaptation limit
exceeded1)

Inoperative - Short circuit, open circuit in wiring or incorrect terminal
assignment (wires interchanged) of connectors between -
G113- and -E87-
- Air flow flap not operating freely
- -G113- in -V71- inoperative- Diagnose and repair short circuit,
open circuit in wiring or confirm
terminal assignment using wiring
diagram

- Check for free operation of air flow
flap2)
- Replace -V71-
00625
Road speed signal

Implausible signal /SP - Loose terminal in wiring/connections between
Speedometer Vehicle Speed Sensor (VSS) G22, the
instrument cluster or in another component also
connected to this signal (e.g. radio or control module for
cruise control) and -E87-
- Speedometer -G21- or instrument cluster supplying
unusable signal or a component disrupts signal - Diagnose and repair loose terminal
using wiring diagram.





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