Volkswagen New Beetle. Manual - part 1416

Fig. 193: Scan Tool Display - A/C System Signal To ECM (4 Of 5) 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

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Switch ON A/C by pressing "Auto" button and selecting lowest temperature. 

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A/C compressor must run.  

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Observe display in Display zone 3.  

If specification not obtained: 

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Specified Value: 1 X 1 (A/C system signal) 

Fig. 194: Scan Tool Display - A/C System Signal To ECM (5 Of 5) 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

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Connect VAG1598/22 (or 1598/31) Test Box to ECM wiring harness. 

 

2003 Volkswagen New Beetle GLS 

1998-2004 ENGINE PERFORMANCE Diesel Fuel Injection, 1.9L ALH - New Beetle

  

Fig. 195: Connecting VAG1598/22 (Or 1598/31) Test Box To ECM Wiring Harness 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

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Check wiring for open circuit between following Test Box socket and A/C system using Wiring diagram. 

Up to MY 1999 

Socket 48 

From MY 2000 

Socket 34 

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Wire resistance: 1.5 ohm maximum  

CAN-Bus, checking 

1. Engine Control Module (ECM)  

2. ABS control module  

3. Transmission Control Module (TCM) 

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Only vehicles with automatic transmission  

4. Airbag control module  

5. Instrument cluster  

6. CAN-Bus 

NOTE:

The following list refers to Fig. 196 .

 

2003 Volkswagen New Beetle GLS 

1998-2004 ENGINE PERFORMANCE Diesel Fuel Injection, 1.9L ALH - New Beetle

  

Fig. 196: Identifying CAN-Bus Components 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

Function 

The Engine Control Module (ECM) (item -1-) communicates with the ABS control module (item -2-), the 
Transmission Control Module (item -3-), the airbag control module (item -4-) and the instrument cluster (item -
5-) via a CAN-Bus (item -6-). 

Function, continued 

At least two control modules capable of CAN - Bus are connected by two wires (CAN-High and CAN-Low, 
twisted together) and exchange information (messages). Missing information on the CAN-Bus will be 
recognized as a malfunction by the ECM as well as by other CAN-Bus control modules. 

All control modules have 120 W terminal resistors which make sure that the CAN-Bus can function without 
fault. 

Special tools and equipment 

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Multimeter (Fluke 83 or equivalent)  

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VW 1594 adapter set  

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Wiring diagram  

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VAG1598/21 Test box  

Test conditions 

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Malfunction has been recognized by CAN-Bus OBD  

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ABS control module coded to CAN-Bus operation  

Test sequence 

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Connect VAG1598/21 test box -1- to ABS control module wiring harness -2-. 

 

2003 Volkswagen New Beetle GLS 

1998-2004 ENGINE PERFORMANCE Diesel Fuel Injection, 1.9L ALH - New Beetle

  

Fig. 197: Connecting VAG1598/21 Test Box To ABS Control Module Wiring Harness 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

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Check terminal resistor in Engine Control Module (ECM) by performing resistance measurement 
between test box sockets 10 + 11.  

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Specified value: 115 to 135 W  

If the resistance value is outside the specified range: 

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Replace Engine Control Module (ECM). See Engine Control Module (ECM), replacing .  

If the resistance value is within the specified range: 

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Check CAN-Bus wiring using wiring diagram. 

 

2003 Volkswagen New Beetle GLS 

1998-2004 ENGINE PERFORMANCE Diesel Fuel Injection, 1.9L ALH - New Beetle