Door locks not working

Chad Hunter

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Good morning,

My 2008 lacrosse cxl is experiencing difficulties with all the doors not locking.
The doors do not respond to the key fob, nor the electronic push button inside the door.
When pushing either the lock/unlock button, I can hear the mechanism trying to operate but nothing happens.
Also the same accrues while putting the vehicle in gear.

This is becoming sort of a nuance, I have to leave the vehicle unlocked at all times.

Any ideas to help remedy this problem?

Thank you all,
Chad
 

HMTJ6821

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Buick LaCrosse 2016
As I understand your description of the symptoms, ALL the door lock mechanisms are attempting to lock but do not complete the task. The only answer that I can conceive is that of a series resistance in the power supply to all the door locks or a low battery voltage (not the same as the charging voltage). If there is corrosion on the battery terminals, fuse block, connectors, or elsewhere in the wiring to the door locks, this could be the cause of a resistance to current flow. Alternatively, if the battery voltage with the engine not running is lower than the normal 12.6 volts, there may not be enough energy available to complete the locking of all four doors simultaneously. Our modern cars today are very sensitive to the condition of the battery.
 

Chad Hunter

New member
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Buick Ownership
Lacrosse
As I understand your description of the symptoms, ALL the door lock mechanisms are attempting to lock but do not complete the task. The only answer that I can conceive is that of a series resistance in the power supply to all the door locks or a low battery voltage (not the same as the charging voltage). If there is corrosion on the battery terminals, fuse block, connectors, or elsewhere in the wiring to the door locks, this could be the cause of a resistance to current flow. Alternatively, if the battery voltage with the engine not running is lower than the normal 12.6 volts, there may not be enough energy available to complete the locking of all four doors simultaneously. Our modern cars today are very sensitive to the condition of the battery.
Thank you for your response, The battery voltage on the car display shows anywhere between 12.6 and 15 at times. The only lock that seems to work is the trunk.
 

2007LucerneCXL

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2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Another item to check is the #3 RECEIVER, some have been able to unplug it and then plug it back in to reset it. It's located on the back shelf under the cover, sorry I don't have information on how to remove the cover.
14319
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SD73

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Before you take things apart you may want to try reaching in from one of the holes in the trunk to the receiver. I can't swear to it, but I'm pretty sure I was able to on my '06 when I was investigating an issue with the rear mounted brake light.
 

Chad Hunter

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Before you take things apart you may want to try reaching in from one of the holes in the trunk to the receiver. I can't swear to it, but I'm pretty sure I was able to on my '06 when I was investigating an issue with the rear mounted brake light.
Thank you for sharing that, indeed I was able to go through the trunk. Unfortunately after unplugging and plugging back in, it still didn't resolve my problem.

Do you think it could be a bad body control module?
 

2007LucerneCXL

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2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Another area that may cause a locking problem is the driver's door master control switch. I'm not sure if this is causing your issue but checking the switch, connections and harnesses for cracks or shorts would eliminate it as a suspect area.
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Chad Hunter

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Lacrosse
Another area that may cause a locking problem is the driver's door master control switch. I'm not sure if this is causing your issue but checking the switch, connections and harnesses for cracks or shorts would eliminate it as a suspect area.

Would that prevent the FOB to not operate the doors as well? Currently the FOB only operates the trunk. The same as the switch for locking/unlocking the doors. Thats the only feature I can get to work either by holding the unlock button on the door up, or using the FOB.
 

2007LucerneCXL

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2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Doors and trunk are on a different switch and harnesses. Most have a trunk switch in the glove box or dash, while the locks run through the driver's door. There was a TSB on another year regarding the door MC and a ground short which was causing havoc so that's why I mentioned it as a option to consider.
 
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