AUDI A4 1995 B5 / 1.G AC System Electrical Testing Workshop Manual

01-115


A/C system, electrical testing

Notes:

Vehicles 1997 page 01
-135
.

VAG1598 test box must not be connected to -
E87- when performing On Board Diagnostic
with VAG1551 Scan Tool (ST)

Test equipment required

Requirements
CAUTION!
Switch multimeter to the appropriate measuring range before
VAG1598 test box with adapter cables VAG1598/11, VAG1598/12
and VAG1594 adapter set Fluke 83 multimeter (US 1119) or equivalentUS 1115 LED tester ThermometerBattery Positive Voltage (B+) OK Ground (GND) connections on engine and transmission OK Fuse No. 42 (S42), 51 (S51), 225 (S225) and 15 (S15) OK
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connecting the test leads to avoid damaging electronic components.
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01-116

VAG1598 test box, connecting


- Switch off ignition.

- Remove A/C control head -E87- and disconnect
all connectors, -A-, -B-, -C- and -D- page 87
-
120
.

Notes: - Connect VAG1598/11 and 12 adapter cables to corresponding
connectors of the vehicle wiring harness (to -E87-).
- Connect VAG1598 test box to the respective adapter cable for
performing measurements.
Do not connect -E87-. When using VAG1598/12 adapter cable, the terminal assignment of
the sockets is identical with the terminal assignment of -E87-. When using VAG1598/11 adapter cable, the terminal assignment of
the sockets is not identical to the terminal assignment of -E87-
terminal assignment, page 01
-117
.
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01-117
Connector terminal assignment of VAG1598 test box with VAG1598/11 adapter cable
Notes:

The terminal assignment of VAG1598/11adapter cable connectors A and B is not identical to the terminal assignment of
sockets on the VAG1598 test box.
The terminal assignment of VAG1598/11 adapter cable terminal C is identical to the terminal assignment of sockets on the
VAG1598 test box.
The terminal assignment of VAG1598/12 adapter cable terminal D is identical to the terminal assignment of sockets on the
VAG1598 test box
As a result of splitting the connectors to A/C control head -E87- using two adapter cables (VAG1598/11 and 12), no
ground connection exists for the test when VAG1598/11 adapter cable is connected. When performing various electrical
tests, it is therefore necessary to use an external Ground source (vehicle body etc.) or a second VAG1598 test box (when
adapter cable VAG1598/12 is connected, Ground exists at sockets 14 and 15).
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01-118

Connector A -E87-
VAG1598 Socket
E87 Connector B
VAG1598 Socket
E87 Connector C
VAG1598 Socket
1 41 1 21 1 1
2 42 2 22 2 2
3 43 3 23 3 3
4 44 4 24 4 4
5 45 5 25 5 5
6 46 6 26 6 6
7 47 7 27 7 7
8 48 8 28 8 8
9 49 9 29 9 9
10 50 10 30 10 10
11 51 11 31 11 11
12 52 12 32 12 12
13 33 13 13
14 34 14 14
15 35 15 15
16 36 16 16
17 37
18 38
19 39
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20 40
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01-119
Electrical testing, 1996

Note:
Electrical testing, 1997 page 01
-135
.
Test
number Component(s) tested:
Page
1
- A/C control head -E87- voltage supply, ground connection and illumination. Page 01
-
120

2
- Temperature sensors G17, G56 and G89 Page 01
-
122

3
- Fresh Air Blower V2 and Control module for fresh air blower J126 Page 01
-
124

4
- Air/temperature distribution flap motors and related potentiometers V68/-G92-, -V70-/G112,
V71/G113 and V85/G114) Page 01
-
126

5
- A/C compressor speed sender G111
- Refrigerant pressure switches -F118- and -F73-
- Interior Temperature Sensor Fan V42
- "A/C compressor intervention" output
- "Excessive engine temperature" signal Page 01
-
128

6
- A/C Clutch Relay J44
- Actuation for coolant fan stage 1 Page 01
-
133

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01-120
Test No. 1 (A/C control head -E87- voltage supply, ground connection and illumination) VAG1598/12 adapter cable Measuring range: Voltage measurement (20 V)
Test
step VAG1598
socket Test of
Test
conditions
- additional
steps Specified
values Corrective action
1.1 9 + 14 Terminal 75x and ground
connection at -E87-
Ignition on - approx.
battery voltage - Repair voltage supply or ground
connection using wiring diagram.
1.2 9 + 15 Ground connection at -
E87- Ignition on - approx.
battery voltage - Repair ground connection using
wiring diagram.
VAG1598/11 adapter cable Measuring range: Resistance measurement (200 ohm)
Test
step VAG1598
socket Test of
Test
conditions
- additional
steps Specified
values Corrective action
1.3 49 + 52 Ground connection at
-E87-
- less than 20
W - Repair ground connection using
wiring diagram.
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01-121

VAG1598/12 adapter cable Measuring range: Voltage measurement (20 V)
Test
step VAG1598
socket Test of
Test
conditions
- additional
steps Specified values
Corrective action
1.4 13 and
ground Terminal 30
at E87
Ignition off - approx. battery voltage - Repair voltage supply using
wiring diagram.
1.5 7 and
ground Terminal 58
at E87 Ignition on Parking
lights on - approx. battery voltage - Repair voltage supply using
wiring diagram.
1.6 7 and
ground Terminal 58
at E87 Ignition on Parking
lights on - less than 2 V - Rectify short circuit to positive
using wiring diagram.
1.7 45 and
ground Terminal 58D
at E87 Ignition on Parking
lights on - 0 to 12 V (depends on
setting of illumination
rheostat) - Determine and rectify open circuit
or short circuit using wiring
diagram.
1.8 45 and
ground Terminal 58D
at E87 Ignition on Parking
lights off - less than 2 V - Rectify short circuit to positive
using wiring diagram.
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01-122
Test No. 2 (temperature sensors G17, G56 and G89) VAG1598/11 adapter cable Measuring range: Resistance measurement (20 kohm)
Test
step VAG1598
socket Test of
Test conditions
- additional steps Specified values
Corrective action
2.1 48 + 52 Outside Air
Temperature
Sensor G17
Measure
temperature at
mounting location
of sensor - resistance table, page 01
-
123
(Resistance values
depend on measured
temperatures at mounting
location of sensor(s)
- Determine and rectify
short circuit, open circuit
in wiring or contact
resistance using wiring
diagram.
- Replace applicable
temperature sensor
page 87
-106

2.2 50 + 52 Instrument Panel
Interior
Temperature
Sensor G56
Measure
temperature at
mounting location
of sensor
2.3 47 + 52 Fresh Air Intake
Duct Temperature
Sensor G89 Measure
temperature at
mounting location
of sensor
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