Instrument Cluster Dimmer Switch Control Unit Input
NOTE:
Before testing instrument dimmer switch control functions, ensure multiplex control system is operating properly. See appropriate MULTIPLEX CONTROL SYSTEMS article in ACCESSORIES & EQUIPMENT.
- Remove driver's underdash fuse/relay box. See DRIVER'S UNDERDASH FUSE/RELAY BOX under REMOVAL & INSTALLATION. Remove driver's multiplex control unit from driver's underdash fuse/relay box. Disconnect driver's multiplex control unit connector. Also disconnect driver's underdash fuse/relay box 18-pin connector "I" and 20-pin connector "O". See Fig 1. Inspect connectors and terminals. Check for bent, loose or corroded terminals. Perform driver's multiplex control unit input test "A". See Fig 2. Repair as necessary and recheck system operation. If driver's multiplex control unit inputs are okay, go to next step.
- Reconnect driver's multiplex control unit to underdash fuse/relay box. Perform input test "B" as specified at back side of driver's fuse/relay box (backprobe). See Fig 2. Repair as necessary.