Page 3 of 47
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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        Page 8 of 47
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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        Page 9 of 47

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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        Page 13 of 47
01-124
 Test No. 3 (Fresh Air Blower V2 and Control module for fresh air blower J126)  VAG1598/11 adapter cable Measuring range: Voltage measurement (20 V)  
Test 
step  VAG1598 
socket  Test of  
Test 
conditions  
- additional 
steps  Specified 
values  Corrective action  
3.1   16 and 
ground  Control module 
for fresh air 
blower J126  
Ignition 
on - Voltage less 
than 5 V 
- Blower does 
not run. - Determine and rectify short circuit to positive in 
wiring/connections between J126 and -E87- 
using wiring diagram. 
- Replace J126
3.2   14 and 
ground  Voltage supply for 
Fresh Air Blower 
V2  Ignition 
on - approx. 
battery 
voltage - Repair voltage supply using wiring diagram.
3.3   11 and 
ground  Voltage supply for 
J126 (via V2)  Ignition 
on - approx. 
battery 
voltage   
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        Page 14 of 47
01-125
 
VAG1598/11 adapter cable 
LED voltage tester US 1115  
Test 
step  VAG1598 
socket  Test of  
Test 
conditions  
- additional 
steps  Specified values  
Corrective action  
3.4   13 + 16   Control module for 
fresh air blower -
J126-  
Ignition 
on - LED in voltage 
tester comes on 
- Fresh air blower 
runs - Determine and rectify open circuit in 
wiring/connections between -J126- and -
E87-. 
- Check Fresh Air Blower V2
operates freely. 
- Replace -J126-.
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        Page 21 of 47

01-131
 
VAG1598/11 adapter cable Measuring range: Voltage measurement (20 V)  
Test 
step  VAG1598 
socket  Test of  
Test 
conditions  
- additional 
steps  Specified 
values  Corrective action  
5.6   3 + ground   A/C Refrigerant Low 
Pressure Switch -F73-  
Ignition on- approx. 
battery voltage - Determine and rectify open circuit in 
voltage supply using wiring diagram. 
- -F73- malfunction   page 87
-66
- Refrigerant circuit empty, refrigerant 
system pressure test   page 87
-190
 
VAG1598/11 adapter cable Measuring range: Amperage (20 amps (A))  
Test 
step  VAG1598 
socket  Test of  
Test 
conditions  
- additional 
steps  Specified 
values  Corrective action  
5.7   44 + 
ground  Interior 
Temperature 
Sensor Fan -V42-  
Ignition 
on - less than 
1 A 
- Blower 
V42 runs - Determine and rectify open circuit, short circuit to 
positive/ground in the wiring/connections between 
V42 and -E87- using wiring diagram. 
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        Page 25 of 47

01-135
 Electrical testing, 1997 
 
Note:  
Electrical testing, 1996   page 01
-119
 . 
Notes:  
 
VAG1598 test box must not be connected to A/C control head -E87- when performing On Board Diagnostic with VAG1551 
Scan Tool (ST) 
 Further notes, test requirements, connecting adapter cables and test equipment   page 01
-115
 .
 From m.y. 1997, do not connect VAG1598 test box to -E87- for test steps 1.1 through 5.7. (Test box only to be connected 
for test steps 5.8, 5.9 and 5.10). Test 
number  Component(s) tested:  
Page  
1  
- A/C control head -E87-, voltage supply and ground connection 
- Signal for time span ignition off Page 01
-
136
   
2  
- Temperature sensors -G17-, G56, -G89- -G191- and -G192-  Page 01
-
138
   
3  
- Fresh air blower -V2-, Control module for fresh air blower -J126-  Page 01
-
140
   
4  
- Air/temperature distribution flap motors and related potentiometers (-V68-/-G92-, -V70-/-
G112-, -V71-/-G113-, -V85-/-G114-)  Page 01
-
141
   
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        Page 27 of 47
01-136
 Test No. 1 (A/C control head -E87- voltage supply, ground connection)  Adapter cable VAG1598/12  
Measuring range: Voltage measurement (20 V)  
Test 
Step  VAG1598 
socket  Test of  
Test 
conditions  
- additional 
steps  Specified value  
Corrective action  
1.1   9 + 14   Terminal 15 and ground 
connection at -E87-  
Ignition on - approx. 
battery voltage. - Repair voltage supply or ground 
connection using wiring diagram. 
1.2   9 + 15   terminal 15 and ground 
connection at -E87-  Ignition on - approx. 
battery voltage. - Repair ground connection using 
wiring diagram. 
1.3    page 01
-120
   
1.4   Not for 1997. Terminal 30 no longer connected  
1.5 to 
1.8   These test steps are conducted only for vehicles up to and including m.y. 1997 (A/C control head with Part. No. 
8D0 820 043 and Part No. 8L0 820 043 up to Part No. index letter "C").  
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