wiring AUDI A4 1996 B5 / 1.G AFC Engine Auxiliary Input Signals Checking Workshop Manual

24-89
If display value does not change:

- Switch ignition OFF and connect VAG 1598/19
test box to ECM harness connector page 01
-
255
.

- Connect VAG 1527B voltage tester between
VAG 1598/19 test box socket C14 and Ground
(GND).

- Switch ignition ON.

- Switch ON rear window defroster.

Voltage tester must light up
If voltage tester does not light up:

If wiring is OK:
If rear window defroster is OK: - Check wiring for continuity between C14 and rear window defroster
using wiring diagram.
- Check rear window defroster using wiring diagram.
- Replace ECM page 01
-265
.
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24-92
If the specified values are obtained:

-
Press button.
- Select "End Output" function 06.

- Press -Q- button to confirm input.
If display value changes:

- The following display is possible: "A/C system
not switched on as described."
If the display value does not change, even
though the A/C system was switched on as
described:

If wiring is OK:
Repair Manual, Heating & Air Conditioning, Repair Group 01; connect VAG 1551 scan tool and select "Check DTC Memory" function 02

Repair Manual, 5 Spd. Automatic Transmission 01V, Repair Group 01;
connect VAG 1551 scan tool and select "Check DTC Memory" function 02
- Check wiring for continuity between connector terminal C11 and ECM
or TCM using wiring diagram.
- Check A/C system or automatic transmission:
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24-94

Engine speed (RPM) signal, checking


Notes:
The RPM signal is routed from the ECM to
various electronic systems (e.g. automatic
transmission, ABS, etc.). The RPM signal is
monitored by the different electronic systems.
Carry out the following check only if the
tachometer (in the instrument cluster) is
inoperative, or if the A/C compressor is not
running.

- Connect VAG 1367 engine-tester to tachometer
using wiring diagram.

- Connect VAG 1367 engine-tester signal wire
(green terminal) to instrument cluster RPM
terminal and A/C control module RPM terminal
(connector remains connected).

- Start engine and let idle.

RPM must be displayed again
If the specified value is obtained, the malfunction
is in instrument cluster or on A/C control module.
If the RPM is not displayed on VAG 1367 engine-
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tester:

- Check wiring between ECM terminal C10 and
instrument cluster or A/C control module using
wiring diagram.
If wiring is OK:

- Replace ECM page 01
-265
.
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24-96

- Switch Fluke 83 multimeter to voltage
measurement range and connect between
signal wire (trip computer 20-pin connector) and
Ground (GND), using wiring diagram.

- Start engine and let idle.

Specified value: approx. 0.3 to 0.6 volts,
corresponding to engine speed (RPM)

- Vary engine speed continuously from 1000 to
4000 RPM.

Specified value: approx. 0.3 to 0.6 volts,
corresponding to engine speed (RPM)
If the specified value is not obtained, even
though the trip computer shows no consumption
value or there is a stored malfunction in the
TCM:

- Stop engine (switch ignition off).

- Replace trip computer and/or TCM as
required.
If the specified value is not obtained:

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If wiring OK and the specified value is not obtained: - Check wiring between ECM terminal C12 and black 20-pin trip
computer connector, using wiring diagram.
- Replace ECM page 01
-265
.
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24-98
If no vehicle speed is displayed between
standstill and moving:

- Switch ignition OFF and connect VAG 1598/19
test box page 01
-255
.

- Connect VAG 1527B voltage tester between test
box sockets 13C (signal) and 10D (B+).

- Raise front of vehicle until left-front wheel is free
to rotate.

Note:
The right front wheel must NOT rotate.

- Switch ignition ON.

Voltage tester must light up at half strength

- Rotate left front wheel by hand.
Voltage tester must become brighter (flash)
If tester does not light up (become brighter) or
flash:

-
Check wiring between test box socket 13X and
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vehicle speed sensor, using wiring diagram.

If wiring is OK, replace vehicle speed sensor.
If voltage tester does not light up (become brighter) or flash, replace ECM
page 01
-265
. - Find and eliminate open circuit in wiring between terminal C13 and
vehicle speed sensor.
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24-100

-
Press button.
- Select "End Output" function 06 and press -Q-
button to confirm input.
If a display did NOT change, even though coding
is OK:

- Connect VAG 1598/19 test box to ECM harness
connector page 01
-255
.

- Connect VAG 1527B voltage tester between test
box sockets 11B (signal) and 10B (constant
B+/terminal 30).

Voltage tester must light up (with TR selector
lever in P or N), then go out with drive mode
(1, 2, 3, R or D) selected
If voltage tester lights up and goes out when
drive mode is selected, even though the range
indicator in the "Read measuring value block" is
OK:

- Replace ECM page 01
-265
.
If voltage tester lights up constantly or not at all:

-
Check wiring for short to ground, short to B+ or open circuit between
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If wiring is OK:
Repair Manual, 5 Spd. Automatic Transmission 01V, Repair Group 01; Electrical test.
ECM terminal 11B and multi-function switch, using wiring diagram.
- Check multi-function switch.
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