Can't get my 2003 4R 4WD to engage. 4WD "motor" or transfer case shift actuator chirps or beeps when 4WD is activated. Unplug "motor" or transfer case shift actuator and a different chirp or beep is heard closer to the passenger side fire wall. Dash idicator light blink in 4WD High, light blink and beeping is heard when switched to 4WD Low. Any advice as to how to troubleshoot?