engine AUDI A4 1999 B5 / 1.G AWM Engine Motronic Injection System Servicing User Guide

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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24-27

Notes:

Idle speed cannot be adjusted.
Idle speed is checked during basic setting of
the engine.
During basic setting, the Evaporative Emission
(EVAP) canister purge regulator valve (EVAP
valve -N80-) is closed and the A/C compressor
is switched off

Test sequence

- Check DTC memory Page 01
-12
. There must
not be any DTCs stored, repair malfunctions if
necessary, erase DTC memory, switch engine
off and start again, road test vehicle and check
DTC memory again as a control measure.

- Let engine continue to run at idle.

WARNING!

The electric fan for the radiator must not be
running.
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24-29


Display on VAS5051:
- Check whether the engine speed in display field -1 (actual engine
speed) is within the permissible specified range.

Display fields

1 2 3 4
Display group 056: Idle stabilization at operating temperature
Display
xxx /min
xxx /min x.x % X X X X X
Indicated
Engine speed (actual)
Engine speed
(specified) Idle control
Torque
change Operating conditions
Specified
value FWD: 740 to 860 RPM
AWD: 760 to 880 RPM FWD: 800 RPM
AWD: 820 RPM x.x % 0 0 0 0 0
Note
If specified value is not obtained
Page 24
-31

Significance of numbers
Page 24
-31
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24-30

Notes:

Engine speed in display field 1 (actual engine
speed) is the current engine speed.
Engine speed in display field 2 (specified
engine speed) is a theoretical engine speed
calculated by the ECM.
At idle, the ECM always attempts to adapt the
engine speed (actual) to the specified engine
speed (specified).
This means that the engine speed (actual) must
always approximately match the engine speed
(specified) at idle.
Display fields 3 and 4 provide information, but
are not relevant for checking idle speed.

Display on VAS5051:
If specified value is obtained:
If specified value is not obtained: -
End function "04 - Basic setting" by pressing button.- Check DTC memory again Page 01
-12
.
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24-32

System pressure, fuel pressure
regulator and residual pressure,
checking


Note:
Fuel pressure regulator regulates fuel pressure
according to intake manifold pressure. This
ensures that the pressure drop at the fuel
injectors remains the same for each speed and
load range of the engine.

Special Tools and Equipment

Test requirements:
Repair Manual, Fuel Supply System, Repair Group 20

VAG1318V.A.G 1318 with V.A.G 1318/11 adapter, V.A.G 1318/12 pressure
hose with connectors and V.A.G 1318/13 adapter Fuel Pump (FP) relay OK; checking Page 24
-52
.
Fuel Pump (FP) OK, checking: Fuel filter OK Battery voltage at least 12.7 V Vehicles with automatic transmission Selector lever in P or N.
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