Center Differential Lock Switch Circuit
- Start engine. Ensure center differential indicator light operates correctly when transfer shift lever is moved to desired 4WD positions. If indicator light does not operate correctly, go to step 3). If indicator light operates correctly, disconnect ECU connector. Using DVOM, check voltage between terminal No. 107 and vehicle ground. See Figure .
- When center differential is locked, battery voltage should not be present. When center differential is unlocked, battery voltage should be present. If voltage is as described, substitute ECU with known good unit and retest. If voltage is not as described, repair wiring harness between ECU and center differential lock detection switch. See Fig 1 . Lock switch can be identified by Brown connector.
- If no indicator lights illuminate, repair 4WD indicator power circuit, or check for faulty 4WD indicator control unit. See 4WD CONTROL UNIT
. If center differential light illuminates, regardless of position of transfer shift lever, check the following:
- Check for short in center differential lock switch circuit.
- Check for faulty center differential lock switch.
- Check for short in ECU circuit or faulty ECU.
- Check for short in indicator control unit circuit or faulty 4WD indicator control unit.
Repair wiring harness or replace component as necessary.
- If center differential light does not illuminate with transfer shift lever in "4H" position, repair wiring harness between 4WD indicator control unit, and center differential lock switch. Check for faulty 4WD indicator control unit.
- If front wheel indicator light does not illuminate with transfer shift lever in "4H" position, repair wiring harness between 4WD indicator control unit and free wheel engage switch. Check vehicle ground wire at engage switch. Check for faulty free wheel engage switch.
NOTE:
When checking for short in ECU circuit, remove ECU connector and ensure 4WD indicator light operates correctly. If 4WD indicator light operates correctly, replace faulty ECU. If 4WD indicator light does not operate correctly, replace faulty 4WD indicator control unit.