Faulty L4 Position Switch
L4 Position Switch harness is open or shorted
L4 Position Switch circuit poor electrical connection
Faulty Engine Control Module (ECM)
Engine Light ON (or Service Engine Soon Warning Light)
The Engine Control Module (ECM) monitors the transfer-case L4 Position Switch to determine when the transfer-case L4 gear is engaged. If the transfer-case L4 gears remain engaged under the following conditions, the ECM will conclude that there is a malfunction of the L4 position switch:
– L4 switch indicated that the L4 transfer-case gears are engaged.
– Transfer case shifter is in the H position.
– Transfer case output shaft rpm is between 1,000 and 3,000 RPM.
– The specified time period has elapsed.
If all of the above conditions are detected, the ECM will conclude that there is a malfunction of the L4 switch and illuminate the Malfunction Indicator Light (MIL) and store the Diagnostic Trouble Code (DTC).