LEMON Manuals: Even more car manuals for everyone
Home >> Volvo >> 1996 >> 850 R, 4D Sedan >> Repair and Diagnosis >> Body & Frame >> Door Locks >> Keyless Entry System >> System Tests >> Functional Tests >> Central Locking System Completely Inoperable

Central Locking System Completely Inoperable

  1. Turn ignition off. Remove fuses No. 3 and 6. See Fig 1 . Replace as necessary. If fuses are okay, check voltage supply leads to each fuse. Repair as necessary. If voltage supply to each fuse is okay, go to next step.
    Fig 1: Locating Engine Compartment Fuse Panel
    G96C09799Courtesy of VOLVO CARS OF NORTH AMERICA.
  2. Ensure ignition is off. Determine if front door and trunk/tailgate can be unlocked and locked using key. Check if rear door can be unlocked by pulling up inside door lock buttons and/or opening them using inside door handles. If any central locking module will not work, fault is mechanical. Repair as necessary. If all central locking modules work mechanically, go to next step.
  3. Ensure ignition is off. Remove central locking relay and driver's door relay. See Figure . Connect ohmmeter between central locking relay connector terminal No. 31 and ground, then between driver's door relay terminal No. 31 and ground. If ohmmeter reads about zero ohms in both cases, go to next step. If ohmmeter does not read about zero ohms in both cases, check for open or short circuit in ground.
  4. Ensure ignition is off. Connect voltmeter between central locking relay connector terminal No. 30 and driver's door relay connector terminal No. 31. See Figure . If battery voltage is present, go to next step. If battery voltage is not present, check for open or short circuit to ground in power supply.
  5. Ensure ignition is off. Connect voltmeter between central locking relay terminals No. 15 and 31. Voltmeter should read about zero volts. Turn ignition on. Voltmeter should read battery voltage. If voltages are to specification, go to next step. If voltages are not to specification, check for open or short circuit to voltage in ignition supply wire between relay terminal No. 15 and fuse No. 3.
  6. Ensure ignition is off. Connect ohmmeter between central locking relay connector terminal M- and No. 31. See Figure . Ohmmeter should read infinite resistance. Connect voltmeter between same terminals. Voltmeter should read about zero volts. If readings are to specification, go to next step. If readings are not to specification, check for short circuit in wiring between relay connector terminal M- and central locking motors. See Figure .
  7. Ensure ignition is off. Connect ohmmeter between central locking relay connector terminals M+ and No. 31, then between driver's door relay connector terminals MD+ and No. 31. See Figure . Ohmmeter should read infinite resistance in both cases. Connect voltmeter between central locking relay connector terminals M+ and No. 31, then between driver's door relay connector terminals MD+ and No. 31. See Figure . Voltmeter should read about zero volts in both cases.
  8. If readings are to specification, go to next step. If readings are not to specification, check for short circuit in wiring between driver's door relay terminal MD+ and driver's door central locking motor. Also check for short circuit in wiring between central locking relay terminal M+ and other central locking motors.
  9. Ensure ignition is off. Lock and close all doors. Connect jumper wire between central locking relay connector terminals M- and No. 30. See Figure . Connect another jumper wire between central locking relay connector terminals M+ and No. 31 for about 2 seconds. See Figure . Central locking except for driver's door should unlock.
  10. Remove jumper wires. Connect jumper wire between central locking relay connector terminals M+ and No. 30. Connect another jumper wire between relay connector terminals M- and No. 31 for about 2 seconds. See Figure . If central locking modules lock, go to step 16). If central locking modules do not lock, go to next step.
  11. Ensure ignition is off. Unlock trunk/tailgate, fuel filler cap, and all doors. Connect ohmmeter between central locking relay connector terminals M- and M+. See Figure . If ohmmeter reads 1-15 ohms, central locking motor windings are okay, but there may be a fault in a central locking motor. Go to step 14). If ohmmeter reads zero ohms, there is a short circuit in wiring between central locking motors and relay connector terminals M- and M+. See Figure . If ohmmeter reads infinite resistance, go to next step.
  12. Ensure ignition is off. Reinstall central locking relay and driver's door relay. Remove panels in doors, luggage compartment, or trunk as necessary. Disconnect central locking module connector.
  13. Connect voltmeter between terminals No. 8 and 12 of front door 14-pin connector, terminals No. 3 and 4 of rear door 8-pin connector, terminals No. 6 and 7 of trunk/tailgate 8-pin connector, and terminals No. 1 and 2 of fuel filler cap 2-pin connector. See Fig 2 . If voltmeter reads about zero volts in each test, go to next step. If voltmeter does not read about zero volts in each test, go to step 27).
    Fig 2: Identifying Keyless Entry System Electrical Connectors
    G96I09801Courtesy of VOLVO CARS OF NORTH AMERICA.
  14. Ensure ignition is off. Remove central locking relay. Remove panels in door, luggage compartment, or trunk as necessary. Disconnect central locking module connector.
  15. Connect ohmmeter between terminals No. 8 and 12 of front door 14-pin connector, terminals No. 3 and 4 of rear door 8-pin connector, terminals No. 6 and 7 of trunk/tailgate 8-pin connector, and terminals No. 1 and 2 of fuel filler cap 2-pin connector. If ohmmeter reads about 1-15 ohms in each test, go to next step. If ohmmeter does not read about 1-15 ohms in each test, check for open circuit or short circuit in central locking module cable harness or central locking motor windings in central locking module where meter indicated incorrect reading.
  16. Ensure ignition is off. Lock driver's door with key and keep key turned as far as it will go. Connect ohmmeter between central locking relay connector terminals No. 31 and LK. Ohmmeter should read about zero ohms. Connect ohmmeter between central locking relay connector terminals No. 31 and ULK. See Figure . Ohmmeter should read infinite resistance.
  17. Unlock driver's door and keep key is turned as far as it will go. Connect ohmmeter between central locking relay connector terminals No. 31 and LK. Ohmmeter should read infinite resistance. Connect ohmmeter between central locking relay connector terminals No. 31 and ULK. See Figure . Ohmmeter should read about zero ohms. If readings are to specification, go to step 27). If readings are not to specification, go to next step.
  18. Ensure ignition is off. Remove door panels from both front doors. Disconnect central locking module 14-pin connector. Lock driver's door with key and keep key turned as far as it will go. Connect ohmmeter between 14-pin connector terminals No. 7 and 14. See Fig 2 . Ohmmeter should read infinite resistance. Connect ohmmeter between 14-pin connector terminals No. 13 and 14. See Fig 2 . Ohmmeter should read about zero ohms.
  19. Unlock driver's door with key and keep key turned as far as it will go. Connect ohmmeter between 14-pin connector terminals No. 7 and 14. Ohmmeter should read about zero ohms. Connect ohmmeter between 14-pin connector terminals No. 13 and 14. See Fig 2 . Ohmmeter should read infinite resistance. Repeat procedure for passenger door. If all readings are to specification, go to next step. If all readings are not to specification, check for defective central locking module control switch or cable harness.
  20. Ensure ignition is off and door panels are removed from both front doors. Ensure central locking module 14-pin connector is disconnected. Connect ohmmeter between central locking module 14-pin connector terminal No. 14 and ground. See Fig 2 . Repeat procedure for passenger door. If ohmmeter reads about zero ohms, go to next step. If ohmmeter does not read about zero ohms, check for open or short circuit in ground wire.
  21. Turn ignition off. Lock driver's door with key and keep key turned as far as it will go. Connect ohmmeter between central locking relay connector terminal No. 31 and LK. See Figure . Ohmmeter should read about zero ohms.
  22. Unlock driver's door with key and keep key turned as far as it will go. Connect ohmmeter between central locking relay connector terminal No. 31 and LK. See Figure . Ohmmeter should read infinite resistance.
  23. If readings are to specification, check for open or short circuit in unlocking signal lead between front door central locking module and central locking relay. If readings are not to specification, check for open or short circuit in signal lead between front door central locking module and central locking relay. Go to next step.
  24. Ensure ignition is off. Remove central locking relay and driver's door relay. Connect voltmeter between central locking relay connector terminals No. 31 and RD. See Figure . Voltmeter should read zero volts. Connect ohmmeter between driver's door relay connector terminals No. 31 and RD. See Figure . Ohmmeter should read infinite resistance. Connect ohmmeter between driver's door relay terminal RD and central locking relay terminal RD. Ohmmeter should read about zero ohms.
  25. If all readings are okay, go to next step. If all readings are not okay, check for open or short circuit in signal lead between terminal RD on central locking relay and terminal RD on driver's door relay.
  26. Turn ignition off. Ensure driver's door relay is installed. Disconnect central locking relay. Lock driver's door. Connect jumper wire between central locking relay connector terminals M- and No. 31. See Figure . If driver's door central locking module switches to unlocked position, go to next step. If driver's door central locking module does not switch to unlocked position, replace driver's door relay.
  27. Ensure ignition is on. Set passenger compartment dome light switch to position "O". Remove central locking relay. Connect voltmeter between relay connector terminals LA and No. 31. See Figure . If voltmeter reads about zero volts, install new central locking relay. If voltmeter does not read about zero volts, check for short to voltage in interior lighting signal wiring between relay connector terminal LA and dome light. See Figure .
scientia non olet · About LEMON Manuals