ignition AUDI A4 1999 B5 / 1.G AC System On Board Diagnostic User Guide

01-24

VAG1551 scan tool
display Possible cause
Corrective action
00000
No DTC recognized If "no DTC recognized appears after performing repairs, OBD is ended.
00529 2122
Speed information
missing /SP1) - Open circuit in wiring between Engine Control Module
(ECM), instrument cluster and A/C control head -E87-
- ECM and instrument cluster supply an unusable engine
speed signal - Diagnose and repair open circuit in
wiring using wiring diagram
- Read measuring value block
page 01
-63

- Test engine speed signal
Repair Manual, Fuel Injection &
Ignition, Repair Group 24
00532 2234
Supply voltage

Signal too low /SP - Voltage drops in electrical system to levels of less than
9.5 V2)
- Contact resistance in cable connection to A/C
Refrigerant Low Pressure Switch -F73- - Test Generator (GEN) and Voltage
Regulator (VR)
Repair Manual, Engine
Mechanical, Repair Group 27
- Diagnose and repair contact
resistance using wiring diagram
1)This fault may be generated during Output Diagnostic Test Mode (DTM) (no engine speed signal recognized although A/C
compressor speed detected).
2) If voltage at -E87-connector -C3- drops below 9.5 V, compressor switches off for a minimum of 25 seconds. Compressor
switches on again when voltage exceeds 10.8 V.
Pa
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01-31

VAG1551 scan tool
display Possible cause
Corrective action
00801 3311
A/C Refrigerant High
Pressure Switch F118

Open circuit/short circuit to
positive /SP - Open circuit in wiring/connections between -F118-
and -E87-
- Malfunction in operation of coolant fan V7 (stage 1)


- Condenser or radiator dirty
- Malfunction of Coolant Fan V7 (stage 2) by A/C
Refrigerant High Pressure Switch F23
- -F23-/-F118-1) malfunction

- Refrigerant circuit malfunction- Diagnose and repair open circuit in
wiring using wiring diagram
- Test fan operation V7 (stage 1)
using
function 03 (Output DTM) page
01
-42

- -V7- electrical test page 01
-115
- Clean condenser and radiator
- Test V7 (stage 2) from -F23-
page 87
-64


- Test F23/F118 page 87
-64

(switching pressures)
- Check refrigerant system pressures
page 87
-192
.
1)F118 and F23 are integrated into the same housing.
Note:
If an open A/C Refrigerant High Pressure Switch -F118- was recognized 30 times during a driving period (e.g. because of a
loose contact), the compressor is switched off. Compressor can be switched on again by pressing "compressor on" button or
by switching ignition off and on. If this fault occurs over several driving periods, compressor cannot be switched on again until
DTC memory is erased.
Pa
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01-32

VAG1551 Scan
Tool Display Possible cause
Corrective action
01044
Control module
incorrectly coded - Coding of A/C control head -E87- not performed according to
specifications.
- Wrong code entered. - Code A/C control head -E87-
according to specifications page
01
-61

01087
Basic setting not
performed - A malfunction occurred during the basic setting function or
ignition was switched off and the A/C control head -E87- could
not complete the function.
- Basic setting was not performed after replacement of the A/C
control head -E87-.
- Basic setting was performed on a non-coded or incorrectly
coded A/C control head -E87-. - Check coding of A/C control head
-E87- page 01
-61

- Perform basic setting of A/C
control head -E87- page 01
-52
.
Note:
The DTCs "Incorrectly coded control module" and "Basic setting not performed" are only stored by A/C control heads -E87-
with one display.
Pa
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01-34

DTC 01270 continued
VAG1551 scan
tool display Possible cause
Corrective action
01270 4121
A/C Clutch N251)

Speed difference
too great /SP3)












Continued on
next page. - Ribbed belt loose, slipping



- A/C control head -E87- not coded correctly
- Loose terminal or contact resistance in circuit between
-N25- and A/C clutch relay -J44- or in wiring/connections
between -G111-2)4) and -E87-
- N25 slipping
- Incorrect crankshaft vibration damper (diameter)
- Malfunction in refrigerant circuit (compressor not
operating freely). - Check belt tension Repair Manual,
Engine Mechanical, Repair Group 13
Compare speeds of engine and compressor
using function 08 (Read measuring value
block) page 01
-63

- Code A/C control head -E87- according to
compressor type installed4) "Zexel" or
"Nippondenso" page 01
-57

- Diagnose and repair circuit using wiring
diagram and perform electrical tests
page 01
-115

- -G111-, -J44- electrical test page 01
-
115

- Repair or replace -N25- page 87
-85
- Check for proper vibration damper part
number
- Check compressor for free operation and
replace if necessary page 87
-38

1/2) Continued from page 01
-33

3) If speed difference is 30 % to 60 %, A/C Clutch is switched on again by -E87- for not more than 9 times during a driving
period (ignition off). If speed difference is greater than 60 %, A/C Clutch remains off until engine is started again.
Pa
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When -F129- is recognized to open 30 times during a driving period (Eg.: intermittent contact), the compressor is switched
off. The compressor can be switched on again by pressing the "compressor on" button or by switching ignition off (and
on). If this malfunction occurs frequently, the compressor can only be switched on after erasing the DTC memory.
Pa
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ystem, On Board Dia
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01-40

VAG1551 scan tool
display Possible cause
Corrective action
01206
Signal for time span
ignition off1)

implausible
signal /SP - Short or open circuit in wiring/connections
between instrument cluster and -E87-
- Instrument cluster malfunctioning.- Diagnose and repair short or open circuit in
wiring using wiring diagram.
- Check signal from instrument cluster using
function 08, Read measuring value block
page 01
-86
.
01274 4131
Air Flow Flap Motor -
V71- 2)

blocked or no
current /SP - Short or open circuit in wiring/connections
between -V71- and -E87-.
- Air flap or fresh/recirculated air flap
binding/sticking
- -V71- malfunctioning.- Diagnose and repair short or open circuit in
wiring using wiring diagram.
- Check air flap or fresh/recirculated air flap for
ease of movement.
- Check -V71- using function 03, Output
Diagnostic Test Mode (DTM) page 01
-42
.
1) If A/C control head -E87- is unable to determine the duration of time when ignition is off ("standing time"), DTC 01206
"signal for time span ignition off" is loaded into memory. The A/C control head will then default to a standing time greater than
4 hours. The actual measured values of the outside temperature sensor are then used as instantaneous outside and engine
temperature inputs for A/C system control. When the "heating" mode is selected under these conditions, the fresh air blower -
V2- has a delayed start (even when the actual standing time is less than 4 hours and the engine is warm) page 01
-86
,
Read measuring value block. The outside air temperature display -G106- may also indicate incorrect outside temperature
values.
2) -V71- operates the air flow flap as well as the fresh/recirculated air flap.
Pa
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ystem, On Board Dia
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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.
Pa
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01-55

Erase DTC Memory (function 05)


Requirements

DTC Memory checked

Erasing DTC memory

-
Press button.
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -5-.
Rapid data transfer
Q
05 - Erase DTC Memor
y

Indicated on display
- Press -Q- button to confirm input.
Rapid data transfer
Q
DTC Memor
y is erased!

Indicated on display
-
Press button.
Attention!DTC Memor
y is not interro
gated

Indicated on display
Notes:
If display appears as shown, check DTC memory and follow test
procedures carefully page 01
-18
.
If ignition was switched off between "Check DTC Memory" and "Erase
DTC memory," the memory is not erased. Check DTC memory once
Pa
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Enter address word XX
- Switch ignition off and disconnect VAG1551 Scan Tool (ST) from Data
Link Connector (DLC).
Pa
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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
Pa
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