# Central lock does not work on MKII Jetta 91



## sibusisom (Nov 16, 2009)

My central lock used to work but it finally gave up a few weeks ago, is there anywhere where i can check and test?


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## Eric D (Feb 16, 1999)

*Re: Central lock does not work on MKII Jetta 91 (sibusisom)*

5.2 Central Locking System
The central locking system consists of a special bi-pressure pump in the luggage compartment, connected by vacuum hose to lock activators at each of the doors, at the rear lid, and at the gas tank flap. When the key is turned in the driver's door lock, the master activator turns on the pump to supply pressure to open the locks, or vacuum to close them.
This heading covers only the removal and installation of the mechanical parts, and troubleshooting of the bi-pressure system. If the pump does not run when key is turned, the problem may be electrical. Troubleshoot the pump and the master activator as described in ELECTRICAL SYSTEM.
NOTE-
If the central locking system has not been operated for an extended period, the key may have to be turned several times before the system activates. 
Bi-Pressure System Troubleshooting
When the key is turned in the master activator, all locks should be activated within 2 seconds. A fault is indicated if the pump runs longer than 5 seconds, or if any of the locks do not activate. Replacement hose is available from an authorized Volkswagen dealer. Troubleshooting should be carried out in the sequence given here, even if only one activator is suspected of being faulty. The replacement of faulty components is covered below under separate headings.
To troubleshoot:
1.	Remove the bi-pressure pump from its housing as described in Bi-pressure Pump.
2.	Clamp the hose as shown in Fig. 5-10. Activate the pump using the door key. If the pump runs longer than 5 seconds, either the hose from the pump is leaking, or the pump is faulty. If the pump shuts off within 5 seconds, remove the clamp and continue testing.








Fig. 5-10.	Bi-pressure pump being tested with hose clamp at 1.
3.	Clamp the hose as shown in Fig. 5-11. If the pump runs longer than 5 seconds, the left rear door activator or the hose to it is faulty. If the pump turns off within 5 seconds, remove the clamp and continue testing.








Fig. 5-11.	Left rear door activator being tested with hose clamp at 1, near hose distributor 2.
4.	Clamp the hose as shown in Fig. 5-12. If the pump runs longer than 5 seconds when activated, go to step 6. If the pump turns off within 5 seconds, either the right front or rear door activator, or the hose to them is faulty. Go to step 5. Remove the clamp.








Fig. 5-12.	Hose being clamped (1) in right rear of car. Clamp blocks air flow to right front and rear doors.
5.	To determine which right door activator is faulty, remove the right carpet trim strip and unscrew the lower B-pillar trim. Clamp the hose shown in Fig. 5-13. If the pump runs longer than 5 seconds when activated, the rear door activator or its hose is faulty. If the pump turns off within 5 seconds, the front door activator or its hose is faulty. Remove the clamp.
6.	Clamp the hose shown in Fig. 5-14. If the pump runs longer than 5 seconds when activated, then the rear lid activator or its hose is faulty. If the pump turns off within 5 seconds, the gas tank flap or its hose is faulty. Remove the clamp.








Fig. 5-13.	Hose being clamped (1) near lower part of B-pillar to block air flow to right front door.








Master activator in drivers door. This is a 3 wire switch, center wire is +12v (from fuse #21 15A for CE2 vehicles or fuse #3 15A for CE1 vehicles), opposite ends are signals for open or close to the pump motor.








12.3 Central Locking System
There are two electrical components of the central locking system-the bi-pressure pump in the luggage compartment and the master activator switch in the driver's door. The master activator switch controls the electrical signal to the bi-pressure pump. If the pump does not run when the door key is turned, test the electrical portion of the system as described below. If the pump runs, but the system does not operate, test the bi-pressure system as described in BODY AND INTERIOR.
NOTE -
If the system has not been operated for an extended period of time, several turns of the key may be required to reactivate the system.
To test the system, remove the bi-pressure pump from its housing as described in BODY AND INTERIOR, and disconnect the pump's harness connector. Place the driver's door lock button in the up (open) position. There should be voltage at the pump's harness connector as shown in Fig. 12-2. Place the driver's door lock in the down (locked) position. There should be voltage at the pump's wiring connector as shown in Fig. 12-3. If these conditions are not met, test the switch and the circuit wiring. See CURRENT FLOW DIAGRAMS. The inside door trim panel must be removed as described in BODY AND INTERIOR to reach the master activator connector.








Fig. 12-2.	Test light (shown schematically) connected between terminals of central locking system's bi-pressure pump harness connector for checking for voltage from master activator in driver's door (open position).








Fig. 12-3.	Test light (shown schematically) connected between terminals of central locking system's bi-pressure pump harness connector for checking for voltage from master activator in driver's door (locked position).


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## sibusisom (Nov 16, 2009)

*Re: Central lock does not work on MKII Jetta 91 (Eric D)*

Hi Eric, thank you very much for your reply, i followed the procedure and got to the problem. It was the main door activator that was faulty, all is well now, thanks for your illustration schematic, it helped me understand how the central locking system works and i fixed mine. I was about to spend some few rands and buy the after market central locking system but your reply came in handy.
Thanks once again. Please help me with my rev counter if you can. Thanks.
http://forums.vwvortex.com/zerothread?id=4650110


_Modified by sibusisom at 6:07 AM 12-3-2009_


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## Martinigue (Jul 16, 2018)

*Jetta 3 central locking system faulty*

Hi good day 
I read your post on the central locking system and I am currently sitting with the same problem.
But I can't see the diagram of how you are explaining how to fix the problem or to trouble shoot.
Can you please help me.


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