check engine AUDI A4 1998 B5 / 1.G AHA Engine Multiport Fuel Injection And Ignition System Owner's Manual

24-75

Engine Coolant Temperature (ECT)
sensor, 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

Test requirements
Engine cold
Pa
ge 98 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-76

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.
Read Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -0- and -4- to input display group number 4 (004),
and press -Q- button to confirm input.
Read Measuring Value Block 4 1 2 3 4

Indicated on display (1-4 = display fields)
Pa
ge 99 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-77

- Compare display with specified value for engine
coolant temperature sensor (display field 3):

Display fields

1 2 3 4
Display group 4: General engine data
Display xxx RPM xx.xxx V
xxx.x C
xxx.x C
Indicates Engine
speed
(in 40 RPM
steps) Battery Positive
Voltage (B+) Engine coolant temperature Intake air
temperature
Range 0 - 6800
RPM 0.000 - 16.500 V -46.5 to 141.0 -46.5 to 141.0
Specified
value 0 RPM 10.000 - 14.500 V approx. ambient temperature 1), 2) ---

--- --- If specified value is not attained page 24
-79
,
Evaluation of display group 4
---
1) After a long standing period (approx. 12 hours). 2) If indicated temperature deviates significantly from the ambient temperature, check ECT sensor wiring for resistance or
open circuits.
Pa
ge 100 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-81
If wiring is OK:

- Check ECT sensor resistance across terminal 1 (signal) and terminal 3
(ground).
- Check measured resistance value for appropriate temperature range
using graph below (N24-0157).

Range A: 0-50 C (32-122 F)

Range B: 50-100 C (122-212 F)

Examples:
If resistance is NOT OK:
At 30 C, ECT sensor resistance should be 1500-2000 At 80 C, ECT sensor resistance should be 275-375
- Replace Engine Coolant Temperature (ECT) sensor -G62-.
- 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
.
Pa
ge 105 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-83

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.
Read Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -0- and -4- to input display group number 4 (004),
and press -Q- button to confirm input.
Read Measuring Value Block 4 1 2 3 4

Indicated on display (1-4 = display fields)
Pa
ge 107 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-84

- Compare displayed value with specified value
for intake air temperature (display field 4):

Display fields

1 2 3 4
Display group 4: General engine data
Display xxx RPM xx.xxx V
xxx.x C
xxx.x C
Indicates Engine speed
(in 40 RPM
steps) Battery Positive
Voltage (B+) Engine coolant
temperature Intake air temperature
Range 0 - 6800 RPM 0.000 - 16.500 V -46.5 to 141.0 -46.5 to 141.0
Specified
value 0 RPM 10.000 - 14.500 V --- approx. ambient temperature 1), 2)

--- --- --- Continuation page 24
-85
, Evaluation of
display group 4
1) After a long standing period (approx. 12 hours). 2) If indicated temperature deviates significantly from the ambient temperature, check IAT sensor wiring for resistance or open
circuits.
Pa
ge 108 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-88

Engine Speed (RPM) sensor, checking


Note:
Component locations page 24
-1

Required special tools and test equipment

VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagram

Checking

- Disconnect 3-pin harness connector from engine
speed sensor.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.
Pa
ge 113 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-89


If wiring is OK: - Check wiring for open circuit between ECM/test box and 3-pin harness
connector.

Connector terminal 1 to ECM/test box socket 67
Connector terminal 2 to ECM/test box socket 63
Connector terminal 3 to ECM/test box socket 56
Specified value: max. 1.5
- Check wiring for short circuit between ECM/test box and 3-pin harness
connector, according to wiring diagram.

Connector terminal 2 to ECM/test box socket 67
Connector terminal 1 to ECM/test box socket 63
Connector terminal 1 to ECM/test box socket 56
Specified value:
- Replace engine speed (RPM) sensor -G28-.
- 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
.
Pa
ge 114 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

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.
Pa
ge 115 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-91

- Check battery positive voltage (B+) in display
field 2.

Display fields

1 2 3 4
Display group 4: General engine data
Display xxx RPM xx.xxx V
xxx.x C
xxx.x C
Indicates Engine speed
(in 40 RPM
steps) Battery Positive Voltage (B+)
Terminal 15 Engine coolant
temperature Intake air
temperature
Range 0 - 6800 RPM 0.000 - 16.500 V -46.5 to 141.0 -46.5 to 141.0
Specified
value 0 RPM 10.000 - 14.500 V --- ---

--- If not as specified page 24
-92
, Evaluation
of display group 4
--- ---
If displayed value is OK (as specified):

-
Press button.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.
Pa
ge 117 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1