05 STS Drivers Door lock issue
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Cadillac STS Forum - 2005 through 2012 Discussion, 05 STS Drivers Door lock issue in Past Cadillac Vehicle Discussion; I am trying to figure out what is going on with my drivers door. I have replaced all the modules ...
  1. #1
    swangin50 is offline Cadillac Owners Member
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    05 STS Drivers Door lock issue

    I am trying to figure out what is going on with my drivers door. I have replaced all the modules (but they were used from ebay) and still no luck. The only thing left I think is the door lock actuator and the outer door handle (not sure if that one matters but it does have a wiring harness on it).

    Symptoms- All doors will unlock and lock with remote except the drivers door (but drivers door will lock with remote). Drivers door has to use actual key to open. If you reach in the car press the unlock button you still can't open from outside.

    So you have to pull handle from inside or use the key on the outside.

    Any ideas??

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  3. #2
    EChas3's Avatar
    EChas3 is offline Cadillac Owners Master
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    Re: 05 STS Drivers Door lock issue

    Sounds like the door latch actuator to me.

  4. #3
    swangin50 is offline Cadillac Owners Member
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    Re: 05 STS Drivers Door lock issue

    That's what I was leaning towards. Thanks

  5. #4
    Greg00coupe is offline Cadillac Owners Enthusiast
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    Re: 05 STS Drivers Door lock issue

    We beat this subject up pretty good on this thread a few months back.....

    http://www.cadillacforums.com/forums...wont-open.html

    I'd go with the actuator..........

    But before I'd go there I would check the battery. Too much in these cars depend on a good battery.

    Good luck

  6. #5
    swangin50 is offline Cadillac Owners Member
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    Re: 05 STS Drivers Door lock issue

    Yeah I check and replaced the key fob battery and had the car battery checked. I lucked out and found the door latch actuator on ebay today and bought it, been looking for a couple months now. Big pain in the but having to use the key to unlock the door but got use to it. Will let you know what happens when I replace the latch actuator.

  7. #6
    swangin50 is offline Cadillac Owners Member
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    Re: 05 STS Drivers Door lock issue

    Got the other door latch actuator installed today (from ebay) and door still doesn't work... same symptoms. Drivers door won't unlock with remote only manually with key, pressing unlock from inside still won't unlock door on outside. What does the door control lock module thing in the door do? Any other suggestions?

  8. #7
    Greg00coupe is offline Cadillac Owners Enthusiast
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    Re: 05 STS Drivers Door lock issue

    Did you try to pull codes? When I was chasing this I talked to the dealer and he said there would be codes.

  9. #8
    swangin50 is offline Cadillac Owners Member
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    Re: 05 STS Drivers Door lock issue

    No I didn't pull codes, I'd have to go to the dealer right? Or could a scanner at Napa do it?

  10. #9
    Greg00coupe is offline Cadillac Owners Enthusiast
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    Re: 05 STS Drivers Door lock issue

    Yea you need a scanner. There are threads on here telling which one. Worth a shot to go to NAPA. My friend has a couple of scanners and I don't know which one he uses.

    My dealer wanted $100 to pull the codes but would credit it back to any repairs. Fortunately I never got that far.

  11. #10
    ddalder's Avatar
    ddalder is offline Cadillac Owners Connoisseur
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    Re: 05 STS Drivers Door lock issue

    Personally, I would have taken a different approach. In the absence of a scan tool, I would have used a meter or test light to see if there is any power at the door lock actuator connector (a pulse when the door is supposed to release). If not, check at the output of the driver door module directly. If it is present there, you have a wiring or connector problem. Is it safe to assume the inside unlock button opens all other doors except the drivers? Otherwirse, you may well have a problem with the Driver Door Switch Assembly (DDSA). This also communicates on the GMLAN bus and is an integral part in the door lock functioning correctly. Has this been replaced, or just the DDM? I would assess wiring first and pursue the DDSA if everything checks out okay. If you have access to an appropriate scan tool you can check functionality of things such as the DDSA without simply replacing it just "to see if this fixes the problem".

    Just to be sure, do other functions work correctly on the door (windows, control backlighting, etc)? If not, have you checked the 15A fuse at location 'DRIVER DR MOD' located in the left rear fuse block?

  12. #11
    swangin50 is offline Cadillac Owners Member
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    Re: 05 STS Drivers Door lock issue

    Had to retype, darn... anyways... I didn't even think about checking voltage from actuator or door lock module. Now it's cold as hell outside and we're getting 8" of snow today here in the midwest! So don't plan on working on the car today!

    I think the DDSA works fine since everything else works.
    And yes all the other functions on the door work.
    I'm guessing that I have a bad Door lock module part number 10379097 (I did replace it with another used one, but it could of been bad) Does anyone have a good working one, at a good price?

  13. #12
    ddalder's Avatar
    ddalder is offline Cadillac Owners Connoisseur
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    Re: 05 STS Drivers Door lock issue

    As you seem to know, you can never be sure used parts are functional. There are a couple of possibilities.

    I'm trying to dig out which module stores the door lock state. When you try to open the door by pulling the handle, the system will check to see what the last known state is. If it is locked, the electric actuator will not open the door. If it is unlocked, the actuator will pop the door. Therefore, my question is... Does the responsible module seem to think the last known state is locked, despite using your fob or pressing the unlock switch on the inside of the door?

    The potential is you may have a defective lock/unlock switch which, if it keeps the input to the DDSA low, will it keep the system in a locked status? (Working on this question...) This may be true of the switch on the passenger door as well. This would certainly explain why neither the switch, nor the fob will unlock the door. There may be a problem with the memory in the module that stores the lock status. If the memory can't be updated with a new "unlocked" status, the vehicle will never permit the actuator to open the door. The best way to troubleshoot this is to look at the module data with a Tech2. This would tell you exactly what the door modules and DDSA believe is going on. The DDSA does act as a gateway to the door module. The lock/unlock switch is actually connected to the DDSA. It will interpret when the operator presses the lock or unlock button and broadcasts a serial data message to the door module. It isn't wired directly to the door module. This is why I questioned what may be going on with it initially.

  14. #13
    swangin50 is offline Cadillac Owners Member
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    Re: 05 STS Drivers Door lock issue

    So your saying the lock unlock button on the door panel is bad? Now the light did go out in the switch a while back but it still worked if I remembered correctly and has been out for a while... but your right, that could explain why it doesn't unlock the door. But why would it unlock the other doors and allow me to open from the inside.

    Anyways it seems like you know what your talking about and know more than I do so whatever you think I should replace, I'll give it a shot.

    Thanks

  15. #14
    ddalder's Avatar
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    Re: 05 STS Drivers Door lock issue

    Quote Originally Posted by swangin50 View Post
    So your saying the lock unlock button on the door panel is bad? Now the light did go out in the switch a while back but it still worked if I remembered correctly and has been out for a while... but your right, that could explain why it doesn't unlock the door. But why would it unlock the other doors and allow me to open from the inside.

    Anyways it seems like you know what your talking about and know more than I do so whatever you think I should replace, I'll give it a shot.

    Thanks
    My thought is it could be defective. There are a number of questions and tests that could rule it out. If you can press unlock and the other doors unlock, it is unlikely the switch is faulty. In your original post you indicated you can press unlock and the door still wouldn't open but there was no clear indication it unlocked all the other doors by pressing unlock (except via fob). Keep in mind that opening the doors from the inside is a whole different matter. The inside door handles are directly connected to the mechanism and not dependent on the same factors as (front) outside door handles.

    Something is still nagging at me making me wonder about a possible wiring problem or, the module that stores the last known lock status is not correctly reporting this on a data bus query. It would make sense that the lock status is stored in the door module(s), but because access control can be a more "global" matter, it's possible this data is stored elsewhere. This is a question I'm still working on.

    I don't know that I'd recommend replacing anything else just yet. It's better to take a systematic approach to troubleshooting and determine where the problem actually exists. You could potentially keep replacing parts until the problem is resolved, however this can be expensive. If it is something like wiring, all the module and switch replacements in the world will never resolve the fault. "Remote" troubleshooting is also difficult, but not impossible. Like I mentioned, check the wiring with a meter when your weather improves. To watch the various module data with a Tech2 would be invaluable. Codes, if there are any could also certainly shed light on this. I'll continue to post as I find additional info.

  16. #15
    swangin50 is offline Cadillac Owners Member
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    Re: 05 STS Drivers Door lock issue

    Quote Originally Posted by ddalder View Post
    My thought is it could be defective. There are a number of questions and tests that could rule it out. If you can press unlock and the other doors unlock, it is unlikely the switch is faulty. In your original post you indicated you can press unlock and the door still wouldn't open but there was no clear indication it unlocked all the other doors by pressing unlock (except via fob). Keep in mind that opening the doors from the inside is a whole different matter. The inside door handles are directly connected to the mechanism and not dependent on the same factors as (front) outside door handles.

    Something is still nagging at me making me wonder about a possible wiring problem or, the module that stores the last known lock status is not correctly reporting this on a data bus query. It would make sense that the lock status is stored in the door module(s), but because access control can be a more "global" matter, it's possible this data is stored elsewhere. This is a question I'm still working on.

    I don't know that I'd recommend replacing anything else just yet. It's better to take a systematic approach to troubleshooting and determine where the problem actually exists. You could potentially keep replacing parts until the problem is resolved, however this can be expensive. If it is something like wiring, all the module and switch replacements in the world will never resolve the fault. "Remote" troubleshooting is also difficult, but not impossible. Like I mentioned, check the wiring with a meter when your weather improves. To watch the various module data with a Tech2 would be invaluable. Codes, if there are any could also certainly shed light on this. I'll continue to post as I find additional info.
    You are correct, when I press unlock on the button on the inside it does unlock the other doors. Everything on the door works on the inside, also my remote start won't work currently.

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