Troubleshooting the alarm or keyless entry for mk3 jetta or passat 
difficulty 3/5
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Introduction

If you are reading this, there is a problem with your alarm/keyless entry.  The actual work is not too hard, but it does take some time, effort, and understanding.  Obviously, disconnect the battery if you are cutting wires, or if the troubleshooter says so.  Make sure to print out this circuit diagram: Alarm/keyless entry circuit diagram and use it as a worksheet.

Also available are the door circuit diagram.  Also see: 1000q: keyless entry retrofit for more information on the alarm system, keyless entry, and ignition lock system.

Feel free to sign up and ask a question about this article at the forums here: myturbodiesel.com forums

Table of Contents

Procedure

SYSTEM DOES NOT OPERATE

NOTE: Ensure battery is fully charged and all fuses are okay.

1) Ground Circuit Check

Obtain radio security code. Disconnect battery cable terminals. Disconnect anti-theft control module 6-pin and 10-pin wring harness connector. See ANTI-THEFT CONTROL MODULE LOCATION table. Connect ohmmeter negative lead to ground. Connect positive lead to anti-theft control module 10-pin wiring harness connector terminal No. "3" (Brown wire). If continuity is present, go to next step. If

continuity is not present, repair open circuit.

2) Power Circuit Check

Connect battery cable terminals. Connect voltmeter negative lead to ground. Connect positive lead to anti-theft control module 6-pin wiring harness connector terminal No. "3" (Red wire). Switch positive lead to anti-theft control module 10-pin wiring harness connector terminal No. "1" (Red wire). If 12 volts are present at both terminals, go to next step. If 12 volts are not present, repair open circuit.

3) Turn ignition on. Leave voltmeter negative lead connected to ground. Connect positive lead to anti-theft control module 10-pin wiring harness connector terminal No. "4" (Black wire for Corrado; Black/Yellow wire for Passat). If 12 volts are present, go to next step. If 12 volts are not present, repair open circuit.

4) Alarm Horn Check

Turn ignition off. Connect ohmmeter negative lead to ground. Connect positive lead to anti-theft control module 6-pin wiring harness connector terminal No. "4" (Black/Yellow wire). If continuity

is present, go to next step. If continuity is not present, repair open circuit. If circuit is okay, replace alarm horn.

5) Door Lock Switch Check

Connect voltmeter negative lead to ground. Connect positive lead to anti-theft control module 10-pin wiring harness connector terminal No. "7" (Red/Yellow wire for Corrado; Yellow/Red for Passat). Insert key in driver's door lock. Turn key to lock position and hold momentarily. Voltmeter should register 12 volts. Repeat procedure for passengers door. If voltage is correct for each door, go to next step. If voltage is not correct, repair open circuit or replace switch.

6) Door Lock Switch Check

Connect voltmeter negative lead to ground. Connect positive lead to anti-theft control module 10-pin wiring harness connector terminal No. "6" (Red/Black wire). Insert key in driver's door lock. Turn key to unlocked position and hold momentarily. Voltmeter should register 12 volts. Repeat procedure for passengers door. If voltage is correct for each door, go to next step. If voltage is not correct, repair open circuit or replace switch.

7) Alarm Switch & Hood Check

Connect ohmmeter negative lead to ground. Disconnect negative battery cable. Connect positive lead to the following anti-theft control module connector terminals: * 10-pin harness connector terminal No. "5" (Gray wire). * 10-pin harness connector terminal No. "8" (Brown/Red wire). * 10-pin harness connector terminal No. "9" (Brown/Green wire). * 10-pin harness connector terminal No. 10 (Brown/White wire for

Corrado SLC; Brown/Green wire for Passat). If continuity is present, check for circuit short to ground. If circuit is okay, replace switch. If continuity is not present, go to next step.

8) Indicator Light Check

Leave ohmmeter negative lead connected to ground. Connect negative battery cable. Using multimeter set on 10 A DC scale, connect positive lead to anti-theft control module 10-pin wiring harness connector terminal No. "2". If indicator light comes on, replace antitheft control module. If indicator light does not come on, repair open circuit in wiring harness.

ALARM SYSTEM WILL NOT SWITCH OFF

1) Ground Circuit Check

Ensure battery is fully charged. Obtain radio security code. Disconnect battery cable terminals. Disconnect anti-theft control module 6-pin and 10-pin wiring harness connector. See ANTI-THEFT CONTROL MODULE LOCATION table. Reconnect battery cable terminals.

2) Connect voltmeter negative lead to ground. Connect positive lead to anti-theft control module 10-pin wiring harness connector terminal No. "7" (Red/Yellow wire for Corrado SLC; Yellow/Red wire for Passat). Insert key in driver's door lock. Turn key against stop and hold momentarily. Voltmeter should register 12 volts. Repeat procedure for passengers door. If voltage is correct for each door, go to next step. If voltage is correct, repair door switch or open circuit.

3) Door Lock Switch Check

Connect voltmeter negative lead to ground. Connect positive lead to anti-theft control module 10-pin wiring harness connector terminal No. "6" (Red/Black wire). Insert key in driver's door lock. Turn key against stop and hold momentarily. Voltmeter should register 12 volts. Repeat procedure for passengers door. If voltage is correct for each door, replace control module. If voltage is not correct, repair door switch or open circuit.

ALARM HORN INOPERATIVE

1) Alarm Horn Check

Ensure battery is fully charged. Obtain radio security code. Disconnect battery cable terminals. Disconnect anti-theft control module 6-pin and 10-pin wiring harness connector. See ANTI-THEFT CONTROL MODULE LOCATION table.

2) Connect ohmmeter negative lead to ground. Connect positive lead to anti-theft control module 6-pin wiring harness connector terminal No. "4" (Black/Yellow wire). If continuity is present, replace anti-theft control module. If continuity is not present, check for open circuit and repair as necessary. If circuit is okay, replace alarm horn.

LIGHTS DO NOT FLASH

1) Alarm Horn Check

Ensure battery is fully charged and emergency flasher system is functional. Obtain radio security code. Disconnect battery cable terminals. Disconnect anti-theft control module 6-pin and 10-pin

wiring harness connector. See ANTI-THEFT CONTROL MODULE LOCATION table.

2) Connect voltmeter negative lead to ground. Connect positive lead to anti-theft control module 6-pin wiring harness connector terminal No. "1" (Black/White wire for Corrado SLC; Black Yellow wire for Passat). Turn emergency flashers on. When lights flash on, battery voltage should be present.

3) Remove voltmeter positive from terminal No. "1" and connect to terminal No. "2" (Black/Green wire for Corrado SLC; Green/Black wire for Passat). Turn emergency flashers on. When lights flash on, battery voltage should be present. If voltage is correct, replace anti-theft control module. If voltage is not correct, repair open circuit in wiring harness between anti-theft control module and lights.

ENGINE DOES NOT CRANK WITH ALARM SYSTEM OFF

ANTI-THEFT SYSTEM

1) Alarm Horn Check

Ensure battery is fully charged and emergency flasher system is functional. Obtain radio security code. Disconnect battery cable terminals. Disconnect anti-theft control module 6-pin and 10-pin wiring harness connector. See ANTI-THEFT CONTROL MODULE LOCATION table.

2) Reconnect negative battery cable. Connect voltmeter negative lead to ground. Connect positive lead to anti-theft control module 6-pin wiring harness connector terminal No. "5" (Red/Green wire for Corrado SLC; Red/White wire for Passat). Observe voltmeter while turning ignition to START position. If battery voltage is present, go to next step. If battery voltage is not present, repair circuit to ignition switch.

3) Remove ignition key. Disconnect negative battery cable. Connect ohmmeter negative lead to ground. Connect positive lead to anti-theft control module 6-pin wiring harness connector terminal No. "6" (Red/Black wire for Corrado SLC; Violet/Black wire for Passat). If continuity is present, replace anti-theft control module. If continuity is not present, check wiring harness to starter for open circuit.

 

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