AUDI A6 2000 C5 / 2.G AEB Engine Motronic MFI And Ignition System

24-61

Checking voltage supply

If there is no voltage:
Checking wiring - Disconnect 4-pin harness connector from Mass Air Flow sensor (MAF).
- Connect multimeter US 1119 (Fluke 83 or equivalent) between harness
connector terminals 1 and 3 (to ECM), using adapter cables from VW
1594 connector test kit.
Specified value: 9.0-14.5 volts
- Switch ignition off.
- Check wiring using applicable wiring diagram.
- Switch ignition off.
- Connect VAG 1598/22 test box to ECM harness connector Page 01
-
56
.

- Check wiring for open circuits between ECM/test box and 4-pin MAF
sensor harness connector.

Connector terminal 2 to ECM/test box socket 12
Connector terminal 4 to ECM/test box socket 13
Specified value: max. 1.5
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24-62

- Check wiring for short circuits between terminals
of 4-pin connector, and between connector and
ECM/test box.


Connector terminal 4 to ECM/test box
socket 12

Specified value:

- Switch multimeter to 20 VDC measuring
range.

- Check wiring at 4-pin connector for short circuit
to B+ (battery positive voltage), according to
applicable wiring diagram.


Connector terminal 2 to vehicle Ground

Connector terminal 4 to vehicle Ground

Specified value: 0 volts
If wiring is OK:

- Replace Mass Air Flow sensor (MAF) -G70-.

-
Check readiness code Page 01
-59
. If
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Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
generate new readiness code Page 01
-62
.
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24-63

Engine Coolant Temperature (ECT)
sensor, checking


Required special tools and test equipment

VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable
VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit
Wiring diagram

Test requirements
Engine cold
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24-64

Checking

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with ignition
switched on) Page 01
-7 .
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.
Read Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -0- and -1- to input display group number 1, and
press -Q- button to confirm input.
Read Measuring Value Block 1 1 2 3 4

Indicated on display (1-4 = display fields)
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24-65

- Compare display with specified value for engine
coolant temperature sensor (display field 2):

Display fields

1 2 3 4
Display group 1: Basic function, engine idle speed
Display xxxx RPM
xxx.x C
xx.x% XXXXXX
Indicates Engine
speed
(in 40 RPM
steps) Engine coolant temperature Oxygen sensor control Adjustment
conditions
Range 0-6800
RPM -46.5 to 141.0 C
-25.0 to 25.0 % ---
Specified
value 0 RPM
approx. ambient temperature
1)
Between -10.0 and 10.0%, value
must fluctuate by at least 2 % ---

--- If not as specified Page 24
-66
,
Evaluation of display group 1
--- ---
1) If indicated temperature deviates significantly from the ambient temperature, check ECT sensor wiring for resistance or
open circuits.

- Start engine and let run at idle.

Temperature value must increase evenly
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Notes:

Temperature is displayed in increments of 1.5
C.

If engine performance problems occur within
certain temperature ranges, and if the
temperature values do not increase without
interruption, the temperature signal is
intermittently interrupted and the sensor must
be replaced.
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24-66
If NOT:

- Replace Engine Coolant Temperature (ECT)
sensor -G62-.

-
Press button to advance program
sequence.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.

- Switch ignition off.
Evaluation of display group 1 Display group: 1


Display field: 2
Possible cause
Corrective action
approx. -46.5 C
Open circuit or short circuit in wiring to B+ - Check wiring Page 24
-66
approx. 141.0 C
Short circuit to Ground

Checking wiring

- Connect VAG 1598/22 test box to ECM harness
connector Page 01
-56
.
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- Disconnect 4-pin connector from ECT sensor -
G62-.
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24-67


- Check wiring resistance for open circuit between ECM/test box and 4-
pin ECT sensor connector.

Connector terminal 1 to ECM/test box socket 53
Connector terminal 3 to ECM/test box socket 67
Specified value: max. 1.5

- Check wiring for short circuit between ECM/test box and 4-pin harness
connector according to wiring diagram.

Connector terminal 1 to vehicle Ground
Connector terminal 1 to ECM/test box socket 67
Connector terminal 1 to terminal 3
Connector terminal 3 to vehicle Ground
Specified value:
- Check wiring between ECM and 4-pin harness connector for short
circuit to battery B+. Specified value: 0 volts

Connector terminal 1 to vehicle Ground
Connector terminal 3 to vehicle Ground
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