Component Tests and General Diagnostics

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.


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. Scan Tool Testing and Procedures.
NO, ALWAYS OFF-Check DIFF LOCK indicator lamp control circuit. .


Diagnosis Procedure

Regarding Wiring Diagram information, [1][2]Differential Assembly.

1. CHECK DIFFERENTIAL LOCK CONTROL UNIT POWER AND GROUND SUPPLY

Check the differential lock control unit power and ground supply. P1833.
Is the inspection result normal?
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 and combination meter harness connector.
3.Check continuity between differential lock control unit harness connector M70 (A) terminal 21 and combination meter harness connector M24 (B) terminal 25.





4.Check continuity between differential lock control unit harness connector M70 (A) terminal 21 and ground.





Is the inspection result normal?
YES - Replace combination meter. Service and Repair.
NO- Repair harness or connector.