Lock Indicator Lamp

LOCK INDICATOR LAMP

Description
The DIFF LOCK indicator lamp has power available to it any time the ignition switch is in the ON or START position. The differential lock control unit supplies ground to activate the DIFF LOCK indicator lamp. The DIFF LOCK indicator lamp will go through a prove out at initial key ON. The DIFF LOCK will flash while the differential lock system is activating or while waiting for conditions to be met to activate. Once the differential lock has been engaged, the DIFF LOCK indicator lamp will remain ON. For more information about the DIFF LOCK indicator lamp, refer to the Owner's Manual.

Component Function Check

1. CHECK DIFF LOCK INDICATOR LAMP OPERATION
1. Turn the ignition switch ON.
2. Observe the DIFF LOCK indicator lamp.
Ignition switch ON Indicator prove out
Does the DIFF LOCK indicator lamp prove out normally?
YES >> DIFF LOCK indicator lamp is operating normally.
NO, ALWAYS ON >> Perform self diagnostics on differential lock control unit. Refer to DLN-236, "DIFFERENTIAL LOCK CONTROL UNIT: Diagnosis Description". Scan Tool Testing and Procedures
NO, ALWAYS OFF >> Check DIFF LOCK indicator lamp control circuit. Refer to "Diagnosis Procedure".

Diagnosis Procedure
1. CHECK DIFFERENTIAL LOCK CONTROL UNIT POWER AND GROUND SUPPLY
Check the differential lock control unit power and ground supply. Refer to DLN-252, "DIFFERENTIAL LOCK CONTROL UNIT: Diagnosis Procedure". Power Supply and Ground Circuit
Does the power and around supply check OK?
YES >> GO TO 2.
NO >> Repair or replace malfunctioning component.

2. CHECK HARNESS BETWEEN DIFFERENTIAL LOCK CONTROL UNIT AND COMBINATION METER








1. Turn ignition switch OFF.
2. Disconnect differential lock control unit harness connector B77 and combination meter harness connector M24.
3. Check continuity between differential lock control unit harness connector B77 (A) terminal 21 and combination meter harness connector M24 (B) terminal 14.
4. Check continuity between differential lock control unit harness connector B77 (A) terminal 21 and ground.





Are the continuity test results as specified?
YES >> Check DIFF LOCK indicator lamp bulb and power supply. Refer to MWI-4, "Work Flow". Diagnosis and Repair Workflow
NO >> Repair harness or connector.