Nissan Patrol Y61 Door Lock Problem

Problem

On “new” Patrols, a problem often arises when not all doors are locked from the central locking system or are not locked stably. This problem is complex and arises as a result of an unsuccessful technical solution, aggravated by wear and contamination of the door mechanisms. In view of the circuit design, it is typical for European Patrols produced in 2007. and later. It was recorded on three cars at once, two 2007. and one 2009.

The trouble with this problem is that when you don’t know about it, the car can remain open, and when you know, paranoia arises and the desire to check all the doors manually.

Symptoms

• The doors do not lock with central locking or do not lock consistently (either they lock or not), but the driver's door always locks well.
• The doors always open well.
• When the doors are locked, all the actuators are activated, but they seem to lack just a little force to lock the door. The locking levers on the door handles do not retract completely when the central locking is locked.
• The problem can worsen in cold weather when old grease, dust and dirt in the lock mechanisms harden.

Causes

All four actuators (except the driver's) are connected in parallel and are switched by polarity reversal from one dual miniature relay in the SMART ENTRANCE CONTROL unit, while there is not a hint of any spark protection in the circuit! Each actuator represents a relatively powerful inductive load, and even more so four in parallel, so it is not surprising that over time the relay contacts deteriorate, a voltage drop occurs on them during switching, and the actuators do not have enough power to move worn, dirty, missing wires or acidified door lock positions. On the other hand, for such a situation to occur, only one holder in mechanical locks covered with old dirt and dust is enough.