1999 AUDI A4 AWM Engine Motronic Injection System Servicing Workshop Manual

- Operate starter briefly (engine can also start).

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

- Check wire connection from terminal 2 of
connector to Fuel Pump (FP) relay via fuse for
open circuit and short circuit to Ground (GND):

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
- Repair open circuit or short circuit if
necessary.

Note:
Ground (GND) from the ECM is present at terminal 3 of connector.
If specified value is not obtained: - Connect multimeter to terminal 2 and terminal 3 of connector for
voltage measurement.
- Operate starter briefly (engine can also start).

Specification: approx. battery voltage
- Check wire connections Page 24
-67
.
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If specified value is not obtained: - Connect multimeter to terminal 3 and terminal 4 of connector for
voltage measurement.

Specification: about 5 V
- Check wire connections Page 24
-67
.
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Check wire connections for Mass Air Flow
(MF) sensor

Note:
Signal wire is also checked during wire test.

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

If wire connection is OK: - Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+: Harness connector
Terminal
VAG1598/31 test box
Socket
3 27
4 53
5 29
- Repair open circuit or short circuit if necessary.
- Also check all wires for short circuit to each other.
- Replace Mass Air Flow (MAF) sensor -G70-.
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Intake system, checking for leaks
(unmetered air)


Special tools and equipment

Notes:
Test sequence
VAS5051 with VAG5051/1Engine leak detection spray G 001 800 A1The negative pressure in the intake system sucks in the leak detection
spray with the unmetered air. Leak detection spray decreases ignition
quality and performance of the fuel mixture. This causes a reduction in
engine speed and a sharp increase of CO content. It is absolutely necessary to follow the safety precautions listed on the
can.
- Connect VAS5051 tester Page 01
-7 and select vehicle system "01 -
Engine electronics". Engine must run at idle for this.
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Display on VAS5051:
- Select diagnostic function "08 - Read Measuring Value Block" in
selection -1-.

Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "001" in button field -2- for "display group number 001"
and press Q button to confirm input.
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Display on VAS5051:
If engine speed decreases: - Make note of engine speed in display field -1.
- Spray intake system parts with engine leak detection spray in a
systematic manner.
- Check sprayed part of intake system for leaks, and eliminate the error.
-
Press "08 - erase DTC memory" to end function -button.- Select "06 - End Output"
- Switch ignition off.
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