Component Tests and General Diagnostics

1. Disconnect front axle switch at front axle.
2. Make sure 4WD indicator lamp is on. Disconnect front axle switch connector at the axle. The 4WD indicator lamp should stay on. This indicates that the transfer case switch and front axle switch is good.
3. Disconnect electronic synchronizer connector from transfer case. Connect test lamp from wiring harness connector to a ground. The test lamp should light if not, check transfer case relay.
4. If the test lamp does not light, check circuit for an opens. If none are found, replace clutch coil relay.
5. If the test lamp lights in step 3, check synchronizer coil for continuity. If the coil is open replace it. If the synchronizer coil has continuity then it is probably OK. Recheck fluid levels, linkage adjustments, etc. before determining synchronizer to be faulty.