Part Time Indicator Test

The diagnosis found here addresses an inoperative part time indicator condition. If the problem being diagnosed is related to lamp accuracy, be certain to confirm that the problem is with the lamp or transfer case switch and not with a damaged or inoperative transfer case or transfer case shift linkage. Refer to Transmission and Transfer Case for the proper transfer case diagnosis and testing procedures. If no transfer case problem is found, the following procedure will help to locate a short or open in the part time indicator circuit.

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT AND ISOLATE THE BATTERY NEGATIVE (GROUND) CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE BEFORE PERFORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

Lamp Does Not Illuminate With Part Time Mode Selected
1. Disconnect and isolate the battery negative cable. Disconnect the engine wire harness connector for the transfer case switch from the transfer case switch connector receptacle. Check for continuity between the ground circuit cavity of the engine wire harness connector for the transfer case switch and a good ground. There should be continuity. If OK, go to Step 2. If not OK, repair the open ground circuit to ground (G101) as required.
2. Connect the battery negative cable. Turn the ignition switch to the ON position. Install a jumper wire between the 4WD switch sense (part-time) circuit cavity of the engine wire harness connector for the transfer case switch and a good ground. The part time indicator lamp should light. If OK, replace the faulty transfer case switch. If not OK, go to Step 3.
3. Turn the ignition switch to the OFF position. Disconnect and isolate the battery negative cable. Remove the instrument cluster from the instrument panel. Check for continuity between the 4WD switch sense (part-time) circuit cavities of the instrument panel wire harness connector (Connector C2) for the instrument cluster and the engine wire harness connector for the transfer case switch. There should be continuity. If OK, replace the faulty part time indicator lamp bulb. If not OK, repair the open 4WD switch sense (part-time) circuit between the instrument cluster and the transfer case switch as required.

Lamp Stays Illuminated With Part Time Mode Not Selected
1. Disconnect and isolate the battery negative cable. Disconnect the engine wire harness connector for the transfer case switch from the transfer case switch connector receptacle. Check for continuity between the ground circuit and the 4WD switch sense (part-time) circuit terminals in the transfer case switch connector receptacle. There should be no continuity. If OK, repair the shorted 4WD switch sense (part-time) circuit between the transfer case switch and the instrument cluster as required. If not OK, replace the faulty transfer case switch.