engine AUDI A4 1999 B5 / 1.G AC System On Board Diagnostic Owner's Manual

01-46
Output Diagnostic Test Mode (DTM) table

VAG1551 scan tool display
Specified function
Corrective action
A/C Clutch N25








Notes: - N25 clicks every 2-seconds
- Output of A/C control head -E87- is switched from 0 V to
12 V every 2-seconds2) - Test voltage supply for -
N25- (via A/C Clutch
Relay J44) using wiring
diagram
- Repair or replace -N25-
page 87
-90

- Test circuit and
connectors between A/C
control head -E87-, J44
and -N25- using wiring
diagram
- Replace -E87-

"A/C compressor on" output to
Engine Control Module (ECM)
and -E87- terminal -C12- is
also actuated at the same
time1)
Output of -E87- switched from 0 V to 12 V every 2
seconds can be confirmed by switching compressor on
and off using the "ECON" button while reading the
measured value block of engine control module
Repair Manual, Fuel Injection and Ignition System,
Repair Group 01)

1)Test this "A/C compressor on" signal only if complaints exist. ECM uses signal to compensate for engine load when
compressor engages Repair Manual, "Fuel Injection & Ignition," Repair Group 24 . ECM is capable of switching off the A/C compressor from this signal. Confirm via function 08, Read measuring value block,
page Page 01
-63
, display group 01 and Fuel Injection and Ignition System Repair Manual, Repair group 01: Read
measured value block of ECM with engine running and at same time switch compressor on and off.
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01-54

Notes:

For m.y. 1996, because A/C engine coolant
temperature sensor G110 is not installed on
USA/CDN models, during basic setting, DTC
"00799 engine coolant temperature sensor
G110" is stored and must be erased.
For m.y. 1997 A/C engine coolant temperature
(ECT) sensor -G110- is deleted, and will no
longer load a DTC when checking DTC memory
after ending basic setting.

- Check DTC memory page 01
-18
.

- Erase DTC memory (function 05) and end
output (function 06) page 01
-55
.
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01-57

Code Control Module (function 07)


A/C control head -E87- coding, vehicles 1996

Notes:

A/C control head coding 1997 page 01
-
59
.

A/C control head coding 1998 page 01
-
61
.
A/C control head -E87- coding shows market
application, compressor type and engine type.

Notes:

Zexel A/C compressors are installed from start
of production. During m.y. 1996, Nippondenso
type compressors are installed as a running
change. These compressors are not equipped
with A/C speed sensor G111.
Each time A/C control head -E87- is coded,
basic setting must be performed page 01
-
52
.

If a the display of a newly installed A/C control
head -E87- flashes after switching ignition on
(for approximately 2 minutes), code the control
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01-58

Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -7-.
Rapid data transfer
Q
07 - Code Control Module

Indicated on display
- Press -Q- button to confirm input.
Code Control ModuleEnter code number XXXXX

Indicated on display
Coding m.y. 1996:
Note:
Coding example, m.y. 1996: 0 0 1 6 2
0 = open
0 = open
1 = compressor w/o Compressor Speed Sensor -G111-
(0 = compressor with -G111-) -
Press button.Code
Market
Compressor
Engine
00062
USA/CDN
Zexel
6-cylinder gasoline
00162
USA/CDN
Nippondenso
6-cylinder gasoline
Pa
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6 = 6-cyl. engine
2 = gasoline engine USA/CDN
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01-59

A/C control head -E87- coding, vehicles 1997

Note:
A/C control head coding 1996 page 01
-57
.

Code
Market
Compressor
Engine
04142
USA/CDN
Zexel
4-cylinder
gasoline
04162
USA/CDN
Nippondenso
6-cylinder
gasoline

Note:
Coding example, m.y. 1997: 0 4 1 4 2
0 = open
4 = Audi A4
1 = compressor w/o compressor speed sensor -
G111-
4 = 4-cyl. engine
(6 = 6-cyl. engine)
2 = gasoline engine USA/CDN

Notes:
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01-60

CAUTION!

Part numbers are for reference only.
Always check with your Parts Dept. for the
latest information.
Coding example:

- Enter code "00062" by pressing applicable
buttons on key pad of VAG1551.
Code Control ModuleEnter code number 00062

Indicated on display
Notes: - Press -Q- button to confirm input.
- Perform basic setting page 01
-52
.
Nippondenso A/C compressors must have A/C control head Part No.
index "H" installed to allow coding "00162." If an unrecognized code is entered in a control head, it is suppressed
and coding "00042" (4-cyl. gasoline engine USA) is then stored. When replacing an A/C control head, always refer to the most recent
parts information.
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01-62

Code

Meaning
00 Place holder, unallocated

1 USA

4 4 cylinder engine

6 6 cylinder engine

0 Left Hand Drive gas engine

Coding example

00140 USA 4 cyl. Left Hand Drive gas engine
00160 USA 6 cyl. Left Hand Drive gas engine
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