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  1. #31
    Pit Crew
    Join Date
    Sep 2008
    Uncanny Valley, New England
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    Cadillac XLR

    2013 Graphite Metallic XTS Platinum


    The 2nd gen coupe is likely similar, since a lot of the electronics technology was pioneered on the XTS. Some was in the 1st gen CTS, which I looked into when I owned a CTS-V; but honestly, that car never had an issue for the seven years I had it, so I wasn't forced to learn it in any depth, system-wise.

    All you need is a service manual or a one-day ($10) subscription here: - Providing electronic service information for 1995 to current GM vehicles and you can download all the applicable info you need to determine the differences/similarities.

    Last edited by ccclarke; 11-12-2017 at 07:40 PM.

  2. #32
    Pit Crew Bakertech's Avatar
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    Sep 2013
    Carlisle, Ontario
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    Default Troubleshooting Interior door switch.

    Quote Originally Posted by ccclarke View Post
    Correct. We're discussing a door latch issue when the interior switch is pressed.

    If the door unlatches when the exterior switch pad is pressed, the latch is most likely fine, which tends to direct the troubleshooting in the direction of the interior switch. But there's more to it; after all, this was Cadillac's first attempt at a seriously interconnected vehicle, so we have to look at the Big Picture and try to avoid tunnel vision when troubleshooting.

    Three modules (and the interior door switch) have to operate correctly in order for the passenger side door latch to do it's thing. The RCDLR, (Remote Control Door Lock Receiver) the PDM, (Passenger Door Module) and the BCM (Body Control Module) make the magic happen. The RCDLR and BCM signal the PDM to unlatch the door.

    Digging a little deeper, the RCDLR receives the UNLATCH signal from the exterior and interior door switches. First, it checks the status of the door to determine if it's locked or not. If the door is unlocked, the RCDLR applies a ground to the door latch solenoid. But wait, there's more! You need a supply voltage applied to the solenoid to complete the circuit.

    The PDM receives the door switch UNLATCH signal at the same time as the RCDLR. It checks the status of the window to figure out the height of the window. (This is where the window index count memory resides for each door that the folding top control module checks before it will move the top.) If the window is below it's index position, the PDM allows the latch to be opened. If the window is above it's index point, it drops the window slightly prior to the door unlatching, to avoid damaging the seal and or window glass. When the window is in the correct index position, the PDM sends a signal to the BCM to apply voltage to the window latch. (This is another clue. . . can you tell where this is going?) Remember, all of the above assumes the windows are indexed properly. If the top isn't working, that's always the first thing to check, by the way.

    To summarize, the BCM supplies the solenoid voltage and the RCDLR supplies the ground path to complete the circuit, throwing the latch.

    Here's what I recommend now that you have a good idea of how the circuit should operate:

    1. With the passenger side window fully raised, press the passenger side interior door switch. Does it: Index (drop 4 mm?) If so, does the door latch solenoid make any noise?

    2. With the passenger side window fully lowered, press the passenger side interior door switch. Does the door latch operate or make any noise? (It's okay, press your ear against the exterior door panel while you press the switch, nobody's watching. . . right?)

    3. Repeat steps 1 & 2 with the exterior switch, which should work fine, but inquiring minds wanna know, just to be sure.

    In theory, if the exterior switch operates under these conditions, then the interior switch should too, since they use almost identical signal paths, with the exception of a few wires, connectors, and of course, the two unlatch switches. But seeing as how I'm here and you're there, remote troubleshooting always boils down to educated guessing based on good symptom elaboration, so the more info you can give me, the easier it is to offer potential solutions.

    Drink a beer or two to celebrate your new passenger side door latch troubleshooting skills, then report back with the answers to questions #1 and #2, and I'll walk you through the next exciting steps. One warning: You'll need to buy more beer!

    I immediately went to the garage, (34F) and pressed Accessory Mode. Following Step #1, I opened then fully closed Drivers then Passenger Window.
    I tried the door and it opened 5 times in a row. Not unheard of but not the norm either.
    I did not proceed further as I only have 27 Bud's left.
    I will try Step #2 tomorrow. Thank you so much. Snowing here in ON Canada.

    I do have the 4 Volume Service Manual.
    Last edited by Bakertech; 11-12-2017 at 11:30 PM. Reason: added content

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