Key not always disarming alarm

khill

Original poster
Member
Jan 7, 2012
86
On occasion, when unlocking my car with my key (original or copy), the car doesn't recognize it. I can unlock the door and the alarm will think I'm breaking in. It's the stock anti-theft. In the evening I can tell whether or not it works by if the dome lights come on or not, but I can wind up attracting attention during the daytime.

Is there an easy fix for this? Anyone ever hear of this? I'd hate to have to rekey my car just due to a failing door lock sensor...


Thanks in advance,

Keith

I suppose this should be moved to tech discussion... any help there?
 

MAY03LT

Member
Nov 18, 2011
3,425
Delmarva
khill said:
Anyone ever hear of this?

The same thing happens in my 03. Even thought the key physically unlocks the door, the switch inside the latch won't report an "active" signal to the DDM so the alarm goes off. In my case, I monitored the key status with a tech2 while turning the key. If I turned the key hard (I don't recommend doing that) it would consistently set an active status, a normal turn of the key would not. So I suspect that the switch is faulty and a new latch is the fix.

I think some tests could be done without a tech2. Hook up a DMM to the light green wire on the latch and see if the voltage changes while cycling the door lock with the key. If it doesn't, the switch is likely at fault. Also, you could remove the drivers door panel and lock the door. Briefly hook up a jumper between the light green and dark blue wires of the latch. Then unlock the door and open it. If the alarm does not go off, the switch is likely at fault.
 

MMIN

Member
Feb 26, 2012
55
Is there an easy fix for this? Anyone ever hear of this? I'd hate to have to rekey my car just due to a failing door lock sensor...

I would agree other than the possibily of the light green wire breaking in the boot somewhere it most likely is something with the latch. On a good note the door latch is the weakest part of the OEM alarm I would recommend disconnecting it all together if you had keyless entry. For the cost of the switch I would probably just recommend adding keyless entry so you don't have to use the key at all to get in any more.. We could provide a very cost effective pre-prepped keyless with 2 remotes if your interested would only consist of about 5 wires to hookup under the drivers dash extremely simple and probably cheaper than the latch or a dealers diagnostic fee. Unless you already have keyless remotes, then just use that or pick some OEM ones up cheap and program them.
 

ghenny440

Member
Dec 14, 2011
368
MMIN said:
I would agree other than the possibily of the light green wire breaking in the boot somewhere it most likely is something with the latch. On a good note the door latch is the weakest part of the OEM alarm I would recommend disconnecting it all together if you had keyless entry. For the cost of the switch I would probably just recommend adding keyless entry so you don't have to use the key at all to get in any more.. We could provide a very cost effective pre-prepped keyless with 2 remotes if your interested would only consist of about 5 wires to hookup under the drivers dash extremely simple and probably cheaper than the latch or a dealers diagnostic fee. Unless you already have keyless remotes, then just use that or pick some OEM ones up cheap and program them.

:thumbup:This is my route if i was you also
 

Chickenhawk

Member
Dec 6, 2011
782
This is common. Because we rarely use the key, the contacts get a bit corroded.

I try to use the key every few weeks and I just get into the habit of turning the key and watching for the interior lights to light up before opening the door.
 

khill

Original poster
Member
Jan 7, 2012
86
I have the OEM keyless (and an aftermarket Viper w/ remote start that kills the battery, so it's disconnected) and plenty of remotes. I just don't like carrying the remote around for pocket space. Oh well, first world problems right?

It it most likely corrosion? Think it would hurt anything to spray some electric cleaner in the lock?


Thanks for the replies,

Keith
 

MMIN

Member
Feb 26, 2012
55
It it most likely corrosion? Think it would hurt anything to spray some electric cleaner in the lock?

It wouldn't hurt anything but I'm not sure that would makes its way to the problem. I would pull the door panel, follow the light green wire to the latch unplug it and clean that up good, then loosen and retighten any bolts/nuts holding the latch on. You could throw a meter on the light green wire and mess around turning the key in the door to see when it gets a signal and when it doesn't.
 

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