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Auto doorlocks won't work when cold

Posted by chunkynickschunkymom (My Page) on
Tue, Dec 6, 05 at 19:39

outside. I have replaced the battery in the key. Car in Land Rover Discovery 2000 and this happened lat year when it was really cold, too. I would love to have some idea what this might be before going to the dealership. Feel like I get reemed there everytime. Thanks for any advice


Follow-Up Postings:

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RE: Auto doorlocks won't work when cold

Stand next to your vehicle (so that you can listen and maybe observe some of the inside lock buttons) and try the unlock function on your key fob. If you hear the familiar "clunk" sound, then the unlock system is trying to operate the lock/unlock motor/solenoids.

In this case, the problem is sticky, stubborn door lock system. Most likely, it is the the motor/solenoid. It could be a frozen door lock, but the motor/solenoid units are highly suspect. Remove the inside door upholstry panels to gain access and remedy the sticking condition. It could be interference, gunk on the parts, need for re-lubrication with a cold weather lubricant, or frozen moisture in the motor/solenoids.

If any of the thin elastoner boots on the 'solenoids' are leaking, replace the solenoids hopefully with improved units.

If any solenoids are completely inoperable, then check to see if these are receiving voltage on the lock/unlock command. If the voltage is present, then replace. If the voltage is not present, then trace the circuit to find where the inturruption exists and repair. [In some cases, you may find that the solenoid system is switching the ground connection of the solenoids instead of the hot lead. This changes the logic to be used for circuit traces.] A repair manual with circuit diagrams is needed for circuit traces.

It takes only one drop of moisture frozen on the plunger of a motor/solenoid unit to stall it. That's why the boot is there. It's suppposed to keep moisture and dirt from getting inside the unit.

Sometimes, the boot on a motor/solenoid gets accidently torn when other service is performed inside the door, and goes unnoticed. These boots are very thin and fragile to remain flexible in cold temperatures.


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RE: Auto doorlocks won't work when cold

JemDandy wrote :
[In some cases, you may find that the solenoid system is switching the ground connection of the solenoids instead of the hot lead. This changes the logic to be used for circuit traces.]

This I do not even pretend to comprehend ..I'd guess that this solenoid must run either forward or backward..


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RE: Auto doorlocks won't work when cold

Earthworm:

"This I do not even pretend to comprehend ..I'd guess that this solenoid must run either forward or backward.."

Yes, these units do run forward or backwards, just like a drive for the window regulator. These may appear like a selenoid, but take one apart and you'll find a little motor inside driving a rack and pinion gear. The motor is reversed by reversing the applied voltage.


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