WIS Document: 4029
Model Context: 900 (1998)
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Door switches in central locking system
Fault symptom
Central locking system not working. Not possible to disarm the alarm with the lock, front doors.
Diagnostic procedure
1 Check the operation of the central locking system
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Connect the ISAT scan tool.
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Select "READ VALUES"
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Select "LOCK SIGNAL" or "UNLOCK SIGNAL".
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Lock or unlock the central locking system using the door key lock.
The ISAT scan tool should display "INACTIVE" when the key is in its normal position and "ACTIVE" when the key is turned.
Is ISAT indicating locked and unlocked central locking system correctly?
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yes
Continue with point 2.
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no
Continue fault diagnosis as described in Service Manual 3:2 "Electrical system "Central locking".
2 Check the programming
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Select "PROGRAMMING"
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Select "LOCK DEACTIVATION".
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Check what is programmed in the control module See
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Is "OFF" programmed?
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yes
Change it to "ON".
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no
If "ON" is programmed, continue with point 3.
3 Check the operation of the central locking system (contd.)
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Select "READ VALUES".
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Select "UNLOCK SIGNAL".
The ISAT scan tool should display "INACTIVE" when the key is in its normal position and "ACTIVE" when the key is turned.
Is ISAT indicating the correct value?
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yes
Continue with point 5.
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no
Continue with point 4.
4 Check the wiring
Conduct a continuity test on the cable assembly between
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the control module, pin 17 and the central locking system, pin 5
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the control module, pin 6 and the central locking system, pin 6
The resistance should be < 1 ohm.
Is the resistance correct?
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yes
Continue with point 5.
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no
Repair or replace the wiring harness.
5 Final check
Check to see if the fault symptom remains.
Is the problem still present?
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yes
See "Before replacing a control module".
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no
The remedial measures taken were correct or the fault is of intermittent nature.
Canonical Workshop Redirect
For step-by-step instructions, interactive illustrations, and official wiring diagrams, refer to the human-optimized workshop page below.
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