Courtesy Lights remain on, i.e. will not extinguish after the vehicle is parked, all doors closed, all switches off. Bad timer of some kind?

If the dome lights in your 2009 Cadillac CTS are not turning off, it can be a frustrating issue. Here are some steps to diagnose and potentially fix the problem:
1. **Manually Turn Off the Dome Lights:**
- In most vehicles, including the Cadillac CTS, there's typically a manual switch on or near the dome light itself. Ensure this switch is in the "Off" position.
2. **Check for Open Doors:**
- Make sure all doors, including the trunk and the hood, are completely closed. Sometimes, a door ajar can prevent the dome lights from turning off.
3. **Interior Light Dimmer Control:**
- Check the position of the interior light dimmer control, which is usually located on the headlight switch or dashboard. If it's turned all the way up, it may keep the dome lights on. Adjust it to the lowest setting.
4. **Ignition Switch:**
- Ensure the ignition switch is in the "Off" position. Sometimes, if the ignition switch is left in the "Accessory" position, the dome lights may stay on.
5. **Faulty Door Switches:**
- Each door usually has a door switch that signals the lights to turn on when a door is opened and off when it's closed. One of these switches may be malfunctioning. You can try manually pressing and releasing each door switch to see if the lights respond.
6. **Battery Disconnect and Reconnect:**
- If the above steps don't work, you can disconnect the vehicle's battery for a few minutes and then reconnect it. This can sometimes reset the electrical system and resolve the issue.
7. **Consult the Owner's Manual:**
- Refer to your Cadillac CTS owner's manual for specific information about the dome light controls and troubleshooting tips.
8. **Professional Diagnosis:**
- If the issue persists, it may be related to a more complex electrical problem. In this case, it's advisable to consult a professional mechanic or an auto-electrician to diagnose and repair the problem.
It's important to be patient and methodical when troubleshooting this issue, as it can have various causes. If you're not comfortable working on the electrical system of your vehicle, seeking professional help is a wise choice to avoid further complications.

do you have the light switch on? also there is a little switch on the door that gets pressed when you close it this part could be broken causing the car to think the door has been left open thus leaving on the courtesy lights

Interior Lamps
The interior lighting consist of the following 2 groups. This first group includes lamps that may not be dimmed.
• The cargo lamp
• The dome lamps
• The reading lamps
• The vanity mirror lamps
Courtesy Lamps
The courtesy lamps include the reading lamps, cargo lamp, and dome lamps. The cargo lamp and dome lamps may be manually turned ON or OFF by placing the interior lamp switch in the ON or OFF position. When the driver places the dome lamp defeat switch in the OFF position, these courtesy lamps will be disabled. If a door is opened, the courtesy lamps illuminate. After all the doors have been closed, the courtesy lamps will remain illuminated approximately 15 seconds after the last door closes. The courtesy lamps will also turn ON prior to any door being opened and will remain illuminated approximately 40 seconds when the driver removes the ignition key. The body control module (BCM) will immediately turn OFF the courtesy lamps if a door lock command is received with all of the doors closed, or if the ignition switch is turned to either the ON or RUN position.


These lights ?

Vanity Mirror Lamps
The inadvertent power courtesy lamps supply voltage circuit of the body control module (BCM) provides battery positive voltage to each vanity mirror lamp. When the vanity mirror cover on the sunshade is opened, a switch closes to provide a ground circuit and the vanity lamp illuminates.
Battery Rundown Protection/Inadvertent Power
The body control module (BCM) inadvertent power courtesy lamps supply voltage circuit provides battery positive voltage to all of the interior reading lamps and both visor vanity mirror lamps. In the event that any of these lamps were to remain illuminated for a period of more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power courtesy lamps supply voltage circuit to prevent a total battery discharge condition. Only when the ignition switch is cycled back to the RUN position will the BCM reset the internal timer and reactivate the inadvertent power courtesy lamps supply voltage circuit.
The BCM also utilizes the inadvertent power courtesy lamps supply voltage circuit as a courtesy lamp request signal circuit when none of the lamps in the circuit are illuminated. When a lamp switch is activated, the BCM receives the request for lamp illumination and switches to supplying voltage to the inadvertent power courtesy lamps supply voltage circuit.

Should be a knob on the dash to override courtesy function not timing out....The timer module will have to be replaced.....Disconnect the negative battery cable to keep it from draining the battery..........

. When you open the door or just unlock the door the lights don't come on ?
Vehicle Security Module The vehicle security module receives inputs from the following:

• door ajar switches
• keyless entry keypad
• ignition switch
• remote keyless entry transmitter

The vehicle security module uses these inputs to control an output signal to the instrument cluster which controls the battery saver relay and courtesy lamp output.
Interior Lighting Systems The instrument cluster grounds the battery saver relay and supplies the power for courtesy lamps when any door ajar switch is opened, or the interior lamp (headlamp) switch is closed. The instrument cluster then supplies voltage to the interior lamp circuit. Vehicle speed must be less than 24 kph (15 mph) for the instrument cluster module to keep courtesy lamps on. The interior lamps will remain illuminated for up to 25 seconds after all doors are closed unless the instrument cluster module receives an input from any of the following:

• voltage from the ignition switch
• a vehicle speed signal
• input from the keyless entry keypad through the vehicle security module
• input from the remote keyless entry transmitter lock or panic switch through the vehicle security module

Do you know what body control system DTC'S - diagnostic trouble codes are ?
Instrument Cluster Diagnostic Trouble Code Index DTC Description Source Action B1342 ECU is Defective Instrument Cluster REFER to Section 413-01 . B2499 Courtesy Lamp Output Failure Instrument Cluster Go To Pinpoint Test A . B1320 Driver Door Ajar Circuit Open Instrument Cluster Go To Pinpoint Test A . B1328 Passenger Door Ajar Circuit Open Instrument Cluster Go To Pinpoint Test A . - All Other DTCs Instrument Cluster REFER to Section 419-10 .
Principles of Operation
The autolamp system provides light-sensitive automatic on/off control of the headlamps and parking lamps controlled by the vehicle security module when the headlamp switch is in the autolamps position. When the ignition switch is turned to the RUN or START position with the autolamps feature already enabled and the ambient light level is dark, the vehicle security module will request the headlamps and parking lamps be turned on. When the autolamps are disabled, the vehicle security module will request the headlamps and parking lamps to be turned off, regardless of the ignition switch position. When the vehicle security module has turned on the exterior lamps and the ignition is turned to the OFF or ACCY position, the exterior lamps will remain on for an additional time specified by the customer or the headlamp switch is turned off.
When the autolamps have been enabled and the ignition switch is in the RUN/START position, the vehicle security module will request that the exterior lamps be turned on or off based on ambient light level. If the vehicle enters darkness for at least 15 seconds, the vehicle security module will request the exterior lamps on. If the vehicle enters light for at least 15 seconds, the vehicle security module will request the exterior lamps off. By delaying turning on and off the exterior lamps during short periods of darkness and light, the vehicle security module prevents the exterior lamps from flashing on and off.

• The autolamps are inoperative - do not operate correctly

• Circuitry.
• Photocell.
• Headlamp switch.
• Vehicle security module.

• Go To Pinpoint Test G .

Power Lock
The power lock/unlock feature requests all of the vehicle doors, including the liftgate, be locked or unlocked upon a customer request from any interior door lock switch in the vehicle. The power door locking system functions independently of ignition status or vehicle speed. When the vehicle security module receives an unlock/lock command from any door lock control switch, the vehicle security module will activate relays internal to the module to supply the correct power and grounds for the door lock actuators.
Your best bet , take it to a qualified repair shop .

Courtesy Lights
The courtesy lights come on under the following conditions:
?€¢
Any door is opened.

?€¢
The interior lamp switch is in the ON position.

?€¢
The keyless entry transmitter unlocks the doors (illuminated entry).

When the key is removed from the ignition switch with all of the doors closed, the courtesy lights light for approximately 25 seconds before fading out.
Battery positive voltage (B+) is applied at all times through the IP fuse block CTSY LP/PWR MIR fuse 6A via CKT 640 (ORN) through the body control module (MALL) to the courtesy lights via CKT 1732 (ORN). The MALL provides a ground through CKT 156 (WHT) for the courtesy lights under the following conditions:
?€¢
The MALL receives an input from a door being opened.

?€¢
The MALL receives an input from the interior lamp being turned ON.

?€¢
The MALL receives an input from the doors being unlocked using the keyless entry transmitter.

The courtesy lamps then light.
When the courtesy lights are activated by opening and closing a door, the courtesy lights will remain on for approximately 25 seconds before fading out after all of the doors are closed. If the ignition switch is turned to START or RUN within the 25 seconds, the lights immediately begin to fade out. If a door is left open, the MALL removes battery positive voltage (B+) to the courtesy lights after 10 minutes. When the courtesy lights are activated by the interior lamp switch, the lights remain on as long as the interior lamp switch is in the ON position. When the courtesy lights are activated by unlocking the doors using the keyless entry transmitter, the lights remain on for approximately 40 seconds. If the doors are locked using the keyless entry transmitter within the 40 seconds, the lights immediately begin to fade out.
Body Control Module (MALL) Diagnostic Mode
For a detailed explanation of the MALL module diagnostic mode, refer to Body Control Module Cell 51.
What interior light ? Dome , courtesy lights etc....They don't work with switch, keyless entry , door opening ?
What

Someone will have to test the door switches with a meter. One of them may not be disconnecting from the circuit with the door closed.

Does the van have remote keyless entry (RKE) system ?
Interior Lighting System Description
Vehicles with the optional remote keyless entry (RKE) system have interior lighting controlled by the body control module (BCM).
This vehicle uses a delayed interior lighting system.
The system functions as follows:
• The dome lamps will illuminate when any door is opened.
• The dome lamps will remain on for 20 seconds after the last door is closed.
• The delay is canceled and the dome lamps will go out when the ignition switch is turned to the ON position.
• The illuminated entry function will not operate when the dome lamp defeat switch is in the OFF position.
• The interior lighting system is protected from battery rundown by the retained accessory power (RAP) system. The RAP system functions by shutting down interior lights after 10 minutes (when ignition is OFF).

Interior Lights Circuit Description
When the interior lamps circuits are closed/enabled, the courtesy lamp relay is activated by the two following coil circuits:
• CKT 690 (GRY/BLK) which is the courtesy lamp enable output of the body control module (BCM) driving the coil side of the relay.
• CKT 1732 (ORN) which is the coil output side of the relay going to the potential grounding switches/sources.
When the courtesy lamp relay is enabled, CKT 156 (WHT) (courtesy lamp output) is enabled by the closed contact at the relay and then grounded by CKT 750 (BLK) at G110.
Some of these circuits can also be activated with the headlamp and panel dimmer switch. When this happens, the coil output side of the inadvertent power relay is grounded to the body control module (BCM) via CKT 1393 (DK BLU)
CKT 40 (ORN) from the courtesy fuse drives both input sides of the inadvertent power relay. When the contact is pulled closed, CKT 1732 (ORN) is supplied power, thus driving any lamps/circuits attached that circuit and providing ground.
The body control module (BCM) also monitors the following four door inputs:
• CKT 49 (DK BLU) -- LH door jamb switch input
• CKT 54 (ORN) -- RH door jamb switch input
• CKT 775 (PNK) -- Side door jamb switch input
• CKT 656 (YEL) -- Rear door jamb switch input/liftgate strut switch input (depending on option content)
When the doors are closed, the body control module (BCM) is in a floating state of 0-2 volts. When the doors are opened, the courtesy lamp relay is activated, sending power to the courtesy lamps.
The headlamp and panel dimmer switch also activates the following interior courtesy lamps when the switch is placed in the PARK or HEADLAMP ON positions:
• RF power window switch
• RH power door lock switch
• LH power window switch
• LH power door lock switch
• LH outside rearview mirror control switch
• Rear radio control head
The dome lamps can be disabled by closing the dome lamp defeat switch located on the headlamp and panel dimmer switch.

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Courtesy or Dome Lamps Inoperative
Step
Action
Value(s)
Yes
No
Important: Verify functional bulbs before beginning diagnostic procedure.
1
Did you perform the Lighting Diagnostic System Check?
--
YES - Go to Step 2
NO - Go to Diagnostic System Check - Lighting Systems
2
Are all of the courtesy/dome lamps inoperative?
--
YES - Go to Step 6
NO - Go to Step 3
3
Activate courtesy/dome lamps
With DMM, check for battery voltage from inoperative lamp CKT 1732 (ORN) to ground
Is battery voltage present?
B+
YES - Go to Step 4
NO - Go to Step 5
4
Repair open in CKT 156 (WHT) between inoperative lamp assemply and S214.
Is the repair complete?
--
NO - Go to Step 10
--
5
Repair open in CKT 1732 (ORN) between inoperative lamp assemply and one of the following splices:
• S258
• S301
Is the repair complete?
--
Go to Step 10
--
6
Turn the courtesy lamp switch to the ON position
Check for battery voltage at BCM C2 cavity B12.
Is battery voltage present?
B+
Go to Step 7
Go to Diagnostic System Check - Body Control System in Body Control Systems
7
Verify continuity of the following three circuits with DMM:
• CKT 1732 (ORN) between courtesy lamp relay and body control module
• CKT 156 (WHT) between courtesy lamp relay and S214
• CKT 750 (BLK) between courtesy lamp relay and S206
Are all of the circuits functional?
--
Go to Step 8
Go to Step 9
8
Replace courtesy lamp relay.
Is repair complete?
--
Go to Step 10
--
9
Repair the inoperative circuit.
Is the repair complete?
--
Go to Step 10
--
10
Operate the system in order to verify the repair.
Did you correct the condition?
--
System OK
Go to Step 2

When my "door ajar" light was on it was because the liftgate sensors (switches) indicated that the gate was open, even thought it wasn't. I took off the plastic trim, and took out the sensors - but that isn't necessary. Just soak with the switches with silicone spray, and see if that helps. There is one on each side of the liftgate - I believe both must indicate "closed" for the light to go off.

I have gotten replacement motors at Checkers for both driver and passenger doors - so now I have lifetime replacement motors.. The first time you replace them, a little drilling is needed on the door sheet metal, but it will not show up once the trim is reinstalled. This repair is a little involved, but well within the capability of a novice mechanic.

Is it an old van? Can you see on the door frame a switch does it come out when the door is opened (push in and out a few times). 3 position switch on always / off always and door switch?