wiring diagram AUDI A3 1995 8L / 1.G ATW Engine Ignition System Workshop Manual

28-7


If LED does not light up:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
If LED lights up:
Checking voltage supply
Test requirement:
Electrical Wiring Diagrams, Troubleshooting & Component Locations - Connect VAG1527B voltage tester as follows:Harness connector
Terminal
Measure to
2 B+
4 B+

LED must light up.
- Check wire connections.
- Check voltage supply
Fuses for engine electronics OK
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28-14

Note:
The motronic Engine Control Module (ECM)
power supply relay -J271- supplies voltage to the
ignition coils with power output stages and the
Engine Control Module (ECM) at pin 121.

Test requirement:

Fuses for engine electronics OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Test sequence

- Remove engine cover (arrows).

- Disconnect 4-pin harness connector -1- at one of ignition coils -2-.
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28-17


If wire connection is OK: - Check following connection for open circuit according to wiring
diagram: 3-socket relay carrier in E-box, plenum
chamber, position 2
Terminal
Harness connector at
ignition coils

Terminal
6 1
- Repair open circuit if necessary.
- Check voltage supply of motronic Engine Control Module (ECM) power
supply relay -J271- Page 28
-18
.
- Check activation of motronic Engine Control Module (ECM) power
supply relay -J271- Page 28
-19
.
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28-18

Checking voltage supply

If specified value is not obtained:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
If no malfunctions are found in wires: - Connect multimeter for voltage measurement as follows.3-socket relay carrier in E-box, plenum
chamber, position 2
Terminal
Measure to

2 Engine Ground
(GND)
9 Engine Ground
(GND)

Specification: approx. battery voltage
- Check wire connection between central electronics and voltage supply
relay for open circuit.
- Replace central electrics.
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Test requirements:

Fuses for engine electronics OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Battery voltage at least 12.7 V
Generator OK

Test sequence

- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

- Switch ignition on.

Note:

The plus voltage supply for the Engine Control
Module (ECM) travels via terminal 3 and 121
(terminal 15) as well as terminal 62 (terminal
30).

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- Check wire connections.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
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28-39

- Connect multimeter for voltage measurement as
follows:

VAG1598/31 test box
Socket
Measure to
121
1)

Engine Ground (GND)

1) The motronic Engine Control Module (ECM)
power supply relay -J271- continues to direct
current to terminal 121 of the Engine Control
Module (ECM) for up to 15 minutes after ignition
is switched off.

- Switch ignition on.


Specification: approx. battery voltage
If specified value is not obtained:

- Check wire connections.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

-
Check motronic Engine Control Module (ECM)
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