Courtesy Lights On At All Times

Possible Causes:

Drivers Door Ajar Switch
Drivers Door Ajar Switch Sense Circuit Short To Ground
Instrument Cluster
Panel Lamps Dimmer Signal Circuit Short To Ground
Multifunction Switch
Door Ajar Switch Open
Passenger Door Ajar Switch Sense Circuit Short To Ground
Courtesy Lamp Driver Circuit Short To Ground
Instrument Cluster

Testing

Close all doors. Turn dimmer switch to MID position. Using scan tool, select ELECTRO MECH CLUSTER and INPUTS/OUTPUTS. If driver's door display is CLOSED, go to next step. If passenger's door display is CLOSED, go to step 6 . If both door displays are OPEN, problem does not exist at this time.
Open driver's door. Disconnect driver's door ajar switch connector. See Figure . If scan tool display is CLOSED, go to next step. If scan tool display is OPEN, replace driver's door ajar switch.
Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Check resistance between door ajar switch connector terminal No. 3 (Tan/Yellow wire) and ground. If resistance is more than 100 ohms, go to next step. If resistance is 100 ohms or less, repair short to ground on Tan/Yellow wire.
Check resistance between instrument cluster harness connector C2 terminal No. 15 (Red wire) and ground. See Figure . If resistance is less than 100 ohms, go to next step. If resistance is 100 ohms or more, replace instrument cluster.
Disconnect multifunction switch connector. See Figure . Check resistance between instrument cluster harness connector C2 terminal No. 15 (Red wire) and ground. See Figure . If resistance is less than 200 ohms, repair short to ground on Red wire between multifunction switch and instrument cluster. If resistance is 200 ohms or more, replace multifunction switch.
Open passenger's door. Disconnect passenger's door ajar switch connector. See Figure . If scan tool display is CLOSED, go to next step. If scan tool display is OPEN, replace passenger's door ajar switch.
Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Check resistance of Tan wire between instrument cluster harness connector C2 terminal No. 4 and passenger's door ajar switch harness connector terminal No. 3. See Figure and Figure . If resistance is 100 ohms or more, go to next step. If resistance is less than 100 ohms, repair short to ground on Tan wire.
Check resistance between instrument cluster harness connector C2 terminal No. 5 (Yellow wire) and ground. See Figure . If resistance is less than 100 ohms, repair short to ground on Yellow wire. If resistance is 100 ohms or more, replace instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION.