ignition AUDI A6 1995 C5 / 2.G AHA Engine Multiport Fuel Injection And Ignition System Owner's Manual

24-85
Evaluation of display group 4 Display group: 4


Display field: 4
Possible malfunction cause
Corrective action
constant 25.5 C
Open or short circuit in wiring to B+- Check wiring page 24
-85

Short circuit to ground
approx. ambient temperature Signal intermittently interrupted
Continuation of test page 24
-87
- Check IAT sensor

Wiring, checking:

- Switch ignition off.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.

- Disconnect 2-pin connector from Intake Air
Temperature (IAT) sensor -G42-.

- Check wiring for open circuit, between ECM/test box and 2-pin IAT harness
connector (to ECM).

Connector terminal 1 to ECM/test box socket 54
Connector terminal 2 to ECM/test box socket 67
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24-90

Voltage supply to Engine Control
Module (ECM), checking


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagram

Checking

- Connect VAG1551 or VAG1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with ignition
switched on) page 01
-8 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
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24-93

Checking voltage supply at terminal 30

- Switch ignition off.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.

- Connect multimeter US1119 (Fluke 83 or
equivalent) between ECM/test box sockets 2
(Ground) and 3 (B+), using adapter cables from
VW1594 connector test kit.

Specified value: 10-14.5 volts
If voltage is NOT OK:

- Check wiring according to applicable wiring
diagram.
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24-94

Checking voltage supply at terminal 15

- Switch ignition off.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.

- Connect multimeter between ECM/test box
sockets 1 (B+) and 2 (Ground), using adapter
cables from VW1594 connector test kit.

- Switch ignition on, and check voltage.

Specified value: 10-14.5 volts
If voltage is NOT OK:

- Check wiring according to applicable wiring
diagram.

- Check readiness code page 01
-70
. If
Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
generate new readiness code page 01
-73
.
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24-99

Checking fuel pump relay voltage supply and
actuation

- Remove fuel pump relay -J17- from relay panel
position 6.

Checking fuel pump relay voltage supply

- Switch ignition on.

If voltage is NOT OK: - Connect multimeter US1119 (Fluke 83 or similar) and check for voltage
at relay socket:

Terminals 28 (B+) and 34
Terminals 32 (B+) and 34
Specified values: approx. Battery Positive Voltage (B+)
- Repair wiring according to applicable wiring diagram.
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24-104
If LED does not flicker:

- Switch ignition off.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.

- Check wiring for open circuits between ECM/test
box and fuel injector harness connectors:


Cyl. 1 fuel injector terminal 2 to ECM/test
box socket 73

Cyl. 2 fuel injector terminal 2 to ECM/test
box socket 80

Cyl. 3 fuel injector terminal 2 to ECM/test
box socket 58

Cyl. 4 fuel injector terminal 2 to ECM/test
box socket 65

Cyl. 5 fuel injector terminal 2 to ECM/test
box socket 72

Cyl. 6 fuel injector terminal 2 to ECM/test
box socket 79
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24-107

Checking

- Remove intake air hose between MAF sensor
and intake air noise muffler.

- Remove vacuum hose from Intake Manifold
Tuning (IMT) valve -N156- (change-over valve).

- Remove 5-pin connector from ignition coils, 2-
pin connector from valve for camshaft
adjustment -N208- (bank 2) and 2-pin connector
from camshaft position sensor -G163- (bank 1).

- Disconnect wiring harness from clips on fuel
rail.

- Disconnect fuel rail from intake manifold and remove fuel lines together
with injectors.
- Remove vacuum hose from fuel pressure regulator.
- Remove harness connectors from all injectors.
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24-114
If there is no leak and vacuum connection has no
obstruction:

- Replace fuel pressure regulator.

Checking residual pressure

- Check residual pressure 10 minutes after
shutting off engine.


Cold engine (min.): approx. 2.2 bar (31.9
psi)

Warm engine (min.): approx. 3.0 bar (43.5
psi)

Note:
The higher pressure with a warm engine, caused
by fuel expansion, is normal.
If the specified value is not attained:

- Start engine and, after fuel pressure has
increased, switch ignition off.

- Close shut off valve on VAG1318 pressure
tester.
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