Each mode button and the neutral position on the accessory switch has an indicator. When the ignition is turn ON, all four indicators light simultaneously as an indicator check. With the ignition ON, the transfer case shift control module grounds the indicator control circuit, corresponding to the mode button selected by the vehicle operator. The transfer case shift control module flashes each indicator after a shift has been requested, and continues to flash until the transfer case shift control module completes the shift.

Schematic Reference

Transfer Case Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Transfer Case Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, with a scan tool command all 4 accessory switch indicators ON, one at a time. All 4 indicators should illuminate.
2. If the vehicle passes the Circuit/System Verification, then refer to Testing for Intermittent Conditions and Poor Connections .

1. Ignition OFF, disconnect the accessory switch electrical connector.
2. Verify that a test lamp illuminates between B+ and terminal H of the accessory switch electrical connector.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between terminals A and H of the accessory switch connector.

⇒	If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance.

4. Ignition OFF, connect the accessory switch electrical connector.
5. Ignition OFF, disconnect C1 of the transfer case shift control module.
6. Ignition ON, with a 3A fused jumper wire, individually ground C1 terminals 10, 11, 12, and 13 one at a time. Each indicator lamp should illuminate when the control circuit is grounded.

⇒	If the indicator does not illuminate, test the indicator control circuit for an open/high resistance. If the circuit tests normal, replace the accessory switch.

7. If all circuits test normal, replace the transfer case shift control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.