I have a 2006 cadillac cts. on the message center (stereo) it keeps saying "right rear door ajar" the door is closed but the message keeps displaying. the most annoying part is that it continues to beep. how can I fix this problem?

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Covered by two relays

Cadillac CTS (2008-2014) fuses and relays

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Hey Jeff, any U- codes stored in any modules ?
U1900 Missing CAN message(s) Door(s) ajar, PRNDL, 4x4, instrument cluster (IC), running boards, vehicle speed REFER to Section 418-00 . U2023 Invalid CAN message(s) Door(s) ajar, PRNDL, 4x4, instrument cluster (IC), running boards, vehicle speed REFER to Section 418-00 .
L4 CHECK THE VDM FOR DOOR AJAR INPUT

• Key in ON position.
• Monitor VDM door position status PID.
• Close all doors, liftgate, liftgate glass and power running boards.
• While observing the diagnostic tool, open and close one door.
• Does the door status PID change between CLOSED and AJAR states?

When you open an close the driver door you have no PID change ,right ?
L4 CHECK THE VDM FOR DOOR AJAR INPUT

• Key in ON position.
• Monitor VDM door position status PID.
• Close all doors, liftgate, liftgate glass and power running boards.
• While observing the diagnostic tool, open and close one door.
• Does the door status PID change between CLOSED and AJAR states?

The door ajar input is an input to the Vehicle Security Module , then transmitted over the bus ! You'll have to find a diagram for the med. speed CAN data bus .

should be on the door post or maybe in the closer mechanism..most are faily close to one of the door hinges..

I know in my 06 CTS I had the same problem with the cigarette lighter. It came unclasped. Simply Take the complete part out (the piece with the ashtray and the cigarette lighter together and there is a plug there, make sure it is plugged in. They easily come unplugged because of the constant opening and closing of the component itself. I hope this helps on the DTS model.

go to a chevy dealer and buy a door switch for your vehicle at the parts department. if you are courteous and patient, the parts guy may even give you a tip on installing it and finding the location of the old one. they generally either screw or snap in. this is a dealer item, not a parts store item.

go to the brake pedal siwtch and check voltage there, the center light is not on the same circuit

Who looked at it ? Dealer ? Did the place's you had look at the vehicle hook up a factory scan tool an view data to door module's an the BCM ? Door ajar is a fuction of the door modules an the BCM - body control module . One of these modules is seeing an input that makes it think door is open .
The door ajar indicator system consists of the following components:
• The driver door module (DDM)
• The passenger front door module (PDM)
• The body control module (BCM)
• The instrument panel cluster (IPC)
• The driver information center (DIC)
• The driver door ajar switch
• The passenger door ajar switch
• The left rear door ajar switch
• The right rear door ajar switch
• The liftgate ajar switch

Driver Door Ajar And Passenger Door Ajar
The DDM and PDM receive a discrete input from the respective door ajar switch to indicate the status of the door. The DDM or PDM then communicates this status to the IPC via class 2 message. The IPC, upon receipt of this class 2 message, will illuminate the appropriate door ajar message in the DIC and also send a class 2 message to the radio to activate the door ajar audible warning when the following conditions are met:
• The transmission is removed from PARK
• The vehicle speed is greater then 8.05 km/h (5 mph)
Left Rear Door Ajar And Right Rear Door Ajar
The BCM receives a discrete inputs from both the left and right rear door and liftgate ajar switches to indicate the status of the doors and liftgate. The BCM then communicates this status to the IPC via class 2 message. The IPC, upon receipt of this class 2 message, will illuminate the appropriate door ajar message in the DIC and also send a class 2 message to the radio to activate the door ajar audible warning when the following conditions are met:
• The transmission is removed from PARK
• The vehicle speed is greater then 8.05 km/h (5 mph)

Could have DTC'S - diagnostic trouble codes . Looking at data paramiters on the scan tool tool would show what switch is faulty or what part is .

check your batteries

What's your question ? Tailgate ajar light lit on the instrument cluster ?
The Body Control Module (BCM) monitors the lift glass and the cargo door ajar switches. When the switch closes, the path to ground is completed, and the BCM sends a class 2 message to the instrument cluster to display the CARGO DOOR AJAR message.There are two ajar switches for the rear door ,a left an a right ,the third switch is for the lift glass ajar switch . All three of these switches splice pack SP410 At ground point G410

(Shouldn't have any readings when door(s) and/or window closed.) It's the opposite . switches are open with door closed , G410
In the Body Harness, Behind the RR quarter trim panel near the D-Pillar
It turns out it has nothing to do with rear door. Something about drivers door actuator. NO IT DOESN"T !!!!

it is one of the door switches you can check them by unpluging them on at a time and jumping a wire from one side of the harness to the other to complete the loop then you will find the bad switch