1995 AUDI A4 engine

24-13


The following harness connectors are located below the coolant
expansion tank: Fig. 1 Installation location, harness connectors
1 - 4-pin harness connector, brown
for Oxygen Sensor (O2S) behind Three Way Catalytic Converter
(TWC) -G130- and Oxygen Sensor (O2S) Heater 1 -Z29- (bank 1
sensor 2)
2 - 6-pin harness connector, black
for Heated Oxygen Sensor (HO2S) -G39- beforecatalytic converter
and Oxygen Sensor (O2S) Heater -Z19- (bank 1 sensor 1)
3 - 3-pin harness connector, gray
for Engine Speed (RPM) sensor -G28-
4 - 3-pin harness connector, blue
for Knock Sensor (KS) 2 -G66-
5 - 3-pin harness connector, green
for Knock Sensor (KS) 1 -G61-

Fuel Pump (FP) Relay -J17- is located at position 4 of central electronics
in driver's footwell, left. Fig. 2 Component locations Fuel Pump (FP) Relay -J17-
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24-15


Fig. 5 Installation position, Throttle Position (TP) sensor -G79-
and sender 2 for accelerator pedal position -G185-

Fig. 6 Installation positions in E-box, plenum chamber
1 - Engine Control Module (ECM)
2 - Secondary Air Injection (AIR) pump relay -J299-
3 - Motronic Engine Control Module (ECM) voltage supply relay -J271-
4 - Installation location of fuse S130 for Secondary Air Injection (AIR)
pump
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24-19

Wire and component testing using
VAG1598/31 test box


Notes:

VAG1598/31 test box is designed so that it can
be simultaneously connected to the wiring
harness at the Engine Control Module (ECM)
and also to the ECM itself.
This is advantageous because electronic
engine control remains fully functional (e.g.
measurement of signals with engine running)
when the test box is attached.
Relevant test procedures note whether Engine
Control Module (ECM) should also be
connected to the test box or not.
Always use VAG1594A connector test kit to
attach measurement devices (e.g. VAG1527B
voltage tester, VAG1526 multimeter etc.).

WARNING!

To avoid damaging electronic components,
set measuring range before connecting test
leads and observe all test requirements.
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24-20

Special Tools and Equipment

Procedure
VAG1598/31
- Switch ignition off.
- Remove Engine Control Module (ECM) Page 24
-22
.

After re-connecting the Engine Control Module (ECM), the following
work steps must be performed: - Connect VAG1598/31 test box to connector of wiring harness. Connect
Ground (GND) clip at test box (not visible in illustration) to Ground
(GND). Relevant test procedures note whether Engine Control Module
(ECM) should also be connected to the test box.
- Perform test as described in relevant repair sequence.
- Activate Engine Control Module (ECM) in "Guided Troubleshooting"
below diagnostic object "Engine Control Module (ECM), replacing".
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24-21

Procedure following interruption of
voltage supply


After re-connecting voltage supply, the
following work steps must be performed:

- Activate Engine Control Module (ECM) in
"Guided Troubleshooting" below diagnostic
object "Engine Control Module (ECM),
replacing".
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24-22

Engine Control Module (ECM), replacing


Special Tools and Equipment

Removing
VAS5051 with VAG5051/1
- Connect VAS5051 tester Page 01
-7 and select vehicle system "01 -
Engine electronics". Ignition must remain switched on for this.

VAS5051 tester display will indicate the control module identification and
coding -2-.
- Always allow display of control module identification first and print it
out.
- Compare coding with coding versions Page 01
-73
.
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24-24


- Using a screwdriver, carefully pry off retaining bracket (arrow).

Note:
Adaptation values are erased when connector is disconnected from the
Engine Control Module (ECM), DTC memory content remains intact. - Disengage connector catches (arrows) and disconnect harness
connectors -1- and -2- from control module.
- Remove Engine Control Module (ECM).
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24-25

Installing
Installation is reverse of removal, noting the
following:

After connecting new Engine Control Module
(ECM), the following work steps must be
performed:

- Activate Engine Control Module (ECM) in
"Guided Troubleshooting" below diagnostic
object "Engine Control Module (ECM),
replacing".
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