1997 AUDI A8 ATQ Engine Motronic Injection System Servicing Workshop Manual

24-48

- Bridge terminals 1 and 65 at test box using wires
from VAG1594A adapter test kit.


Fuel Pump (FP) must run.

- Operate VAG1348/3A remote control for 30
seconds.

- After all three fuel injectors of one cylinder row
have been activated, place measuring glasses
on an even surface.

Specified value for each fuel injector: 90 to
125 ml.

- If measured value of one or more fuel injectors
is outside of specified range, switch Fuel Pump
(FP) off (disconnect cable bridge) and replace
faulty fuel injector Page 24
-43
.

- Repeat test at fuel injectors of second cylinder
row.

- If the measured values of all fuel injectors are
outside the specified range, check fuel pressure
Page 24
-30
.

Note:
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Also check spray pattern when checking injection
quantity. Spray pattern must be the same for all
injectors

- Install fuel injectors together with fuel distributor
Page 24
-44
.
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24-49


Fuel Pump (FP) relay -J17- and activation,
checking

Special Tools and Equipment

VAG1526A
VAG1594A
VAG1598/31
VAS5051 with VAG5051/1
- or
VAG1551 with VAG1551/3B
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24-50
Voltage is supplied to the Fuel Pump (FP) and
several components of the injection system via
the Fuel Pump (FP) relay -J17-.
Engine must be turning for Fuel Pump (FP) relay
-J17- to close. This means that the relay does
not receive Ground (GND) (via ECM) until the
ECM recognizes RPM signals.

Note:

Fuel Pump (FP) relay is located at position 4 of central electrics in driver's
footwell, left.
Test requirement:
Battery voltage at least 12.7 V
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24-51

Function test of Fuel Pump (FP) relay

- Remove driver-side storage compartment.

Repair Manual, Body
-Interior, Repair Group
68; Instrument Panel; Removing Driver
-Side
Storage Compartment


- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .

Ignition must remain switched on for this.

- Initiate output Diagnostic Test Mode Page 01
-
56
and activate Evaporative Emission (EVAP)
canister purge regulator valve -N80-.

A - If relay does not trigger:
Fuel Pump (FP) relay (at position 4 of central electrics in driver's
footwell, left) must trigger and Fuel Pump (FP) must run.
- Check voltage supply of Fuel Pump (FP) relay Page 24
-52
.
- Checking activation of Fuel Pump (FP) relay Page 24
-52
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24-52
B - If relay triggers, but Fuel Pump (FP) does not
run:

- Check voltage supply for Fuel Pump (FP) and
components (via Fuel Pump -FP- relay) Page
24
-54
.

Check voltage supply of Fuel Pump (FP)
relay

- Remove Fuel Pump (FP) relay.

If specified value is not obtained:
Checking activation of Fuel Pump (FP) relay - Connect multimeter to terminal 17 of relay socket and Ground (GND)
for voltage measurement.

Specification: approx. battery voltage
- Replace central electrics.
- Switch ignition off.
- Connect VAG1598/31 test box at wiring harness to ECM, do not
connect ECM Page 24
-17
.
- Bridge terminals 1 and 65 at test box using wires from VAG1594A
adapter test kit.
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24-53


If relay triggers now, but didn't during output DTM:
If relay does not trigger:
Fuel Pump (FP) relay (at position 4 of central electrics in driver's
footwell, left) must trigger.
- Replace Engine Control Module (ECM) Page 24
-21
.
- Remove cable bridge.
- Remove Fuel Pump (FP) relay.

If specified value is not obtained:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
binder - Connect multimeter to terminal 19 of relay socket and Ground (GND)
for voltage measurement.

Specification: approx. battery voltage
- Check wire connections.
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24-54
If specified value is obtained:

If no malfunctions are detected:
Check voltage supply for Fuel Pump (FP) and components - Check the following wire connection for open circuit and short circuit to
Ground (GND) and B+:
Central electric
in driver-side footwell, left, position 4
Terminal
VAG1598/31 test box


Socket
16 65
- Repair open circuit or short circuit if necessary.
- Replace Fuel Pump (FP) relay -J17-.
- Re-connect Engine Control Module (ECM).

- Remove fuses S228, S229, and S234 (positions 28, 29, and S234)
from fuse holder.
- Initiate output Diagnostic Test Mode Page 01
-56
and activate
Evaporative Emission (EVAP) canister purge regulator valve -N80-.
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