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Home >> Audi >> 1985 >> 5000CD Turbo (Canada) L5-2144cc 2.14L SOHC Turbo (KH) >> Repair and Diagnosis >> Technical Service Bulletins >> All Technical Service Bulletins >> Auto Check System - Troubleshooting Guide >> Main Control Unit Troubleshooting

Main Control Unit Troubleshooting

Multi-Point Connector:




Troubleshooting
Multi-point connector, 35 point,

measure between terminals: additional steps specifications remarks

27 and ground approx. spec's NOT OK
0 Ohms - repair wire break according to current
flow diagram

7 and 27 switch ignition approx, 12.0V spec's NOT OK
voltage supply ON - repair wire break according to current
flow diagram

1 and 27 start engine approx. 12.0V spec's NOT OK
voltage while starting - repair wire according to current flow diagram

3 and 27 approx. spec's NOT OK
0.3 bar oil pressure switch 0 Ohms - disconnect blue/black wire from oil pressure
switch and connect to ground
- repeat measurement spec's OK
- replace oil pressure switch spec's NOT OK
- repair wire break according to current flow diagram start engine infinity Ohms spec's NOT OK
- disconnect blue/black wire from oil pressure switch
- repeat measurement spec's OK
- replace oil pressure switch spec's NOT OK
- repair short circuit according to current flow diagram
Multi-point connector, 35 point,

measure between terminals: additional steps specifications remarks

2 and 27 infinity Ohms spec's NOT OK
1.8 bar oil pressure switch - disconnect white/gray wire from oil pressure
switch
- repeat measurement spec's OK
- replace oil pressure switch spec's NOT OK
- repair short circuit according to current flow diagram start engine approx. spec's NOT OK
0 Ohms - disconnect white/gray wire from oil pressure
switch and connect to ground
- repeat measurement spec's OK
- replace oil pressure switch spec's NOT OK
- repair wire break according to current flow diagram

4 and 27 fill container infinity Ohms spec's NOT OK
sending unit for windshield with water - disconnect plug from sending unit
washer fluid - repeat measurement
spec's OK
- replace sending unit spec's NOT OK
- repair short circuit according to current flow diagram
Multi-point connector, 35 point,

measure between terminals: additional steps specifications remarks

19 and 27 fuel tank full: spec's NOT OK
fuel level 40 Ohms - repair wire break according to current
fuel tank flow diagram
empty:
282 Ohms

40 to 282 Ohms according to fuel level

20 and 27 run engine approx. 12.0 V spec's NOT OK
terminal 61 from alternator - repair wire break according to current flow
diagram

21 and 27 approx. spec's NOT OK
brake pad wear indicator 0 Ohms - repair wire break according to current flow
diagram
- check brake pads for wear

22 and 27 ignition and less than spec's NOT OK
front bulb control unit, low beam low beam ON 1.5 V - repair wire break according to current flow
headlight diagram
- if more than 3.5 Volts, check for defective bulb bulb OK
- disconnect black plug from rear bulb control unit, Fig. 12
- repeat measurement spec's NOT OK
- replace front bulb control unit, Fig. 9

22 and 27 ignition and spec's NOT OK
rear bulb control unit, tail light parking light - repair wire break according to current flow
ON diagram
- if more than 3.5 Volts, check for defective bulb bulb OK
- disconnect black plug from rear bulb control unit, Fig. 12 and measure voltage supply between terminals 15 and 31 must be approx. 12.0 V
- repeat measurement spec's NOT OK
- replace rear bulb control unit, Fig. 12
Multi-point connector, 35 point,

measure between terminals: additional steps specifications remarks

5 and 27 fill container to infinity Ohms spec's NOT OK
sending unit for brake and Max mark - disconnect plug from brake and hydraulic fluid
hydraulic fluid level

run engine level sending unit, also hydraulic pressure

briefly warning switch
- repeat measurement spec's still NOT OK
- repair short circuit according to current flow diagram
- bridge terminals at plug connector spec's approx. 0 Ohms if not, repair wire break according to current flow diagram spec's OK
- replace appropriate sending unit

25 and 27 reconnect plug 0 Ohms spec's NOT OK
hydraulic pressure warning to hydraulic - check hydraulic pressure warning switch,
switch pressure Fig. 29
switch

6 and 27 positive lead infinity Ohms spec's NOT OK
coolant temperature switch and of Ohmmeter - disconnect plug from coolant level sending
coolant level sending unit connected to unit, Fig. 2
terminal 6 - repeat measurement
spec's OK
If locking diode for A/C is defective, no display will - replace coolant level sending unit
appear for coolant temperature too hot spec's NOT OK
- disconnector plug from coolant temperature switch, Fig. 3
- repeat measurement spec's OK
- replace coolant temperature switch spec's NOT OK
- remove locking diode for A/C and check with Ohmmeter in both directions 346 K Ohms in forward direction 0 Ohms in reverse direction
- repair short circuit according to current flow diagram
Multi-point connector, 35 point,

measure between terminals: additional steps specifications remarks

23 and 27 switch ignition approx. 12.0 V spec's NOT OK
rear bulb control unit brake light ON - repair wire break according to current flow

depress brake less than diagram
pedal 1.5 V - if more than 3.5 Volts, check for defective bulb
if bulb OK
- disconnect black plug from rear bulb control unit, Fig. 12 and measure voltage between terminals 15 and 31 must be approx. 12.0 V
- repeat measurement spec's NOT OK
- replace rear bulb control unit

33 and 27 switch ignition approx. 12.0 V spec's NOT OK
ignition coil terminal 1 ON - repair wire break according to current flow

- diagram

35 and 27 switch ignition approx. 12.0 V spec's NOT OK
terminal 58 and low beam - repair wire break according to current flow
ON diagram

24 and 27 switch ignition approx. 12.0 V spec's NOT OK
push button for Auto-Check ON, press - repair wire break according to current flow
system button for diagram
Auto-Check system
Multi-point connector, 35 point,

measure between terminals: additional steps specifications remarks

11 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for windshield - check wiring according to current flow diagram
- check display unit, Fig. 15

12 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for oil pressure - check wiring according to current flow diagram
- check display unit, Fig. 15

13 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for brake light - check wiring according to current flow diagram
- check display unit, Fig. 15

14 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for fuel reserve - check wiring according to current flow diagram
- check display unit, Fig. 15

15 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for brake fluid level - check wiring according to current flow diagram
- check display unit, Fig. 15

16 and 34 2.5-3.5 Ohms spec's NOT OK
warning light for "Red Triangle" - check wiring according to current flow diagram
symbol - check display unit, Fig. 15

17 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for "OK" symbol
- check wiring according to current flow diagram
- check display unit, Fig. 15
Multi-point connector, 35 point,

measure between terminals: additional steps specifications remarks

28 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for head lights and - check wiring according to current flow diagram
tail lights - check display unit Fig. 15

29 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for battery - check wiring according to current flow diagram
- check display unit, Fig. 15

30 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for coolant - check wiring according to current flow diagram
temperature - check display unit, Fig. 15

32 and 18 2.5-3.5 Ohms spec's NOT OK
warning light for brake pad wear - check wiring according to current flow diagram
- check display unit, Fig. 15

With brake fluid level switch out, it goes immediately to fault with chime.
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