transmission AUDI A4 1997 B5 / 1.G AFC Engine Auxiliary Input Signals Checking Workshop Manual
[x] Cancel search | Manufacturer: AUDI, Model Year: 1997, Model line: A4, Model: AUDI A4 1997 B5 / 1.GPages: 37, PDF Size: 0.15 MB
Page 4 of 37

24-90
      
A/C compressor shut-off signal, 
checking
 
     
Note:  
     The A/C compressor is switched off during 
acceleration by the Engine Control Module 
(ECM) and at wide open throttle by the 
Transmission Control Module (TCM) via the 
kickdown switch. 
     A/C compressor shut-off is bi-directional ("in"and 
"out"). 
     
IN: Shortly before switching the A/C 
compressor on, voltage is applied to the ECM 
which causes the Idle Air Control (IAC) valve to 
open a little more to adjust to the higher load. 
     OUT: When accelerating from a standstill 
position and at lower speed, the A/C 
compressor is shut off for approx. 12 seconds 
via control by the ECM. If the accelerator pedal 
is released early enough, the duration is 
reduced to a minimal 3 seconds. 
     
Checking requirements  
     A/C function OK 
     
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Page 8 of 37

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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Page 10 of 37

24-93
       If X1X_XX is displayed:  
     
-  Briefly press accelerator pedal to apply wide 
open throttle. 
     
Display must switch briefly to X0X_XX, then 
X1X_XX must appear again after several 
seconds. 
      If display does not change as described:  
     
-  Check whether A/C compressor was shut off 
while accelerator pedal was being pressed. 
     
-  Check A/C system or automatic transmission.
     
       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  
      If the display does not change as described:  
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Page 12 of 37

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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Page 14 of 37

24-95
      
Fuel consumption signal, checking
 
     
Notes:  
     
The consumption signal is internally calculated 
by the ECM using "injection time." 
     The consumption signal is routed to both the 
trip computer and the Transmission Control 
Module (TCM). 
     The consumption signal is monitored by the 
TCM 
     
       Repair Manual, 5 Spd. Automatic 
Transmission 01V, Repair Group 01; On Board Diagnostic
   
      Carry out the following check only if DTC 
memory contains a stored DTC for the TCM 
related to the consumption signal, or a missing or 
false consumption signal, determined during the 
trip computer check.  
     
-  Remove instrument cluster or TCM.
     
       Repair Manual, Electrical Equipment, Repair 
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Page 15 of 37

Group 90; Instrument cluster, repairing
   
     
       Repair Manual, 5 Spd. Automatic 
Transmission 01V, Repair Group 01, On Board Diagnostic
   
     
-  Connect VAG 1598 test box to instrument 
cluster harness connector (I/P insert not 
connected) or to TCM harness connector (TCM 
not connected). 
     
       Repair Manual, Electrical Equipment, Repair 
Group 90; Instrument cluster, repairing
   
     
       Repair Manual, 5 Spd. Automatic 
Transmission 01V; Repair Group 01, On Board Diagnostic
   
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Page 18 of 37

24-97
      
Vehicle speed signal, checking
 
     
Note:  
     The vehicle speed signal originates from the 
vehicle speed sensor (on the transmission) and 
is routed to the instrument cluster as well as to 
the Engine Control Module (ECM). 
     
Speedometer in instrument cluster OK 
     
Checking  
     
-  Using VAG 1551 scan tool, select "Read 
Measuring Value Block" function 08, display 
group 003   page 01
-249
 . 
Read measuring value block 3 1 2 3 4
    
Indicated on display  
-  Observe display field 4 while accelerating from standstill.
   Specified values: 
 
0 mph (at standstill) 
 Actual speed (vehicle driven)
- 
Press  button.
-  Select "End Output" function 06.
-  Press -Q- button to confirm input.
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Page 21 of 37

24-99
      
Transmission Range (TR) selector lever 
position signal, checking
 
     
Note:  
     The Engine Control Module (ECM) uses this 
signal to recognize the transmission range 
selector lever position. When a driving mode is 
selected, idle speed should drop by approx. 50 
RPM to reduce creep. 
     
Checking requirement  
     
Control module coding OK   page 01
-247
 . 
     
-  Switch ignition ON.
     
-  Using VAG 1551 scan tool, select "Read 
Measuring Value Block" function 08, display 
group 004, display field 4   page 01
-249
 . 
Read measuring value block 4 1 2 3 4
    
Indicated on display  
CAUTION!     Specified value: XXX_1X (TR selector lever in P or N)
-  Apply brake and select drive mode (1, 2, 3, R or D).
   Specified value: XXX_0X 
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Page 24 of 37

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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Page 25 of 37

24-101
      
Shift procedure, checking
 
     
Notes:  
     
The Engine Control Module (ECM) uses this 
signal to briefly retard the ignition during shifting 
to reduce the mechanical jerking felt between 
shifts. 
     The shift signal is monitored by the 
Transmission Control Module (TCM). 
     
       Repair Manual, 5 Spd. Automatic 
Transmission 01V, Repair Group 01; On Board Diagnostic
   
      Carry out the following check only if a shift-
related DTC is stored in the TCM DTC memory.  
     
Checking requirement  
     
Control module coding OK   page 01
-247
 
     
CAUTION! 
     
Always use a second technician to operate 
the VAG 1551 scan tool while driving.  
     
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