SFN-20240112C Installing axle differential lock

TICO Document #: SFN-20240112C (formerly TES 148)

Description of Procedure: Installation of axle differential lock engagement switch.

Units Affected: Units with Meritor 24160, 23186, and MOR axles

Parts Required: AXLE DIFFERENTIAL LOCK KIT 720934 (QTY 1)

Planned Labor: 2 hour

Note: Follow Meritor’s guidelines for installation of carrier into axle. Refer to Meritor’s TP-7824, MM5, TP1162, TP9238, TP9579, and MM-09168 documents for carrier removal and assembly as well as differential lock operation.

Instructions:

1. Park the vehicle on a flat surface, apply parking brake, and chock wheels. If your company utilizes a “Lock Out, Tag Out” policy, you should employ it during this procedure.

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2. Release/vent all air in the system. This can be done by manually releasing valves at the bottom of the air tank.

3. Remove battery box cover and disconnect battery cables. Remove batteries or insulate terminals ends with a non-conductive wrap to prevent inadvertent contact between battery terminals and cables.

5. Inside cab, loosen turn signal switch from steering column using a flat-head screwdriver or 5/16 bit driver.

6. Remove diagnostic panel by removing #10 socket head screws with 1/8” hex key wrench. Panel is located at lower left-hand side of dash cover. There are six screws for this panel.

7. Behind diagnostic panel, disconnect the connectors for the engine diagnostic switch, the increment/decrement switch, and abs diagnostic switch if applicable.

8. Push connectors back into the dash bucket.

9. Remove switch blank, shown left.

10. Insert 91206 differential lock switch into cavity where switch blank was removed.

11. Set Diagnostic panel aside for now.

12. Remove key switch panel from dash cover assembly by removing four #10 socket head screws with 1/8” hex key wrench.

13. Gently pull key switch panel away from dash cover. Remove connector for A/C switch and push it back into dash bucket.

14. Return key switch panel to original position.

    Note: Do not secure panel in place at this time.

15. Remove gauge panel by removing #10 socket head screws with 1/8” hex key wrench. Panel is located at top of dash cover. There are seven screws for this panel.

16. Gently tilt the gauge panel away from dash cover. This will expose the back of the panel and the wires attached to the gauges.

17. On top right-hand side of gauge panel, remove connections for the floodlights/work lights switch, strobe light switch, and motorized mirror switch if applicable.

18. Splice DIMMER, red wire from 620530 differential lock harness into purple wire (DA 118) on the rear of flood/work lights switch at about 4” from connector.

19. Remove air line(s) for air pressure gauge.

    Note: On split brake systems, there will be two air lines, green and black.

20. Continue lifting gauge panel away from dash cover assembly. Locate connector between dash gauge harness and cab PDC harness, shown above.

21. Unscrew connectors and securement hardware using 5/16 bit driver.

22. Remove leads to the hour meter, shown on left.

    Note: red wire on terminal 1, white wire on terminal 2, and brown wire on terminal 3.

23. Remove dash gauge panel with attached harness from dash cover and bucket assembly.

22. Connect 620531 differential lock harness 12-way connector to differential lock switch, 91206.

23. Route 2-way weather pack connector of 620531 harnesses down shifter tube, located directly under the shifter panel on the dash.

24. Splice SUPPLY lead, purple wire, from 620531 differential lock harness into F19 circuit at 4” behind the fuse holder, lower left of the dash. Install 5 amp fuse into F19 circuit.

Note: F19 circuit is the suggested power source. However, dependent upon options installed on units F13, F21, F22, F23, or F24, circuits may be used with 5 amp fuse installed. If these circuits are unavailable for use, then utilize F20 accessory circuit.

25. Secure the 5/16” ring terminal from the 620530 harnesses to the cab PDC ground stud, shown on the left.

26. Prepare air solenoid on 620531 three-way air solenoid harness as shown by installing three 40860 elbow fittings.

27. Reinstall batteries and reattach battery cables.

28. Raise cab and secure at the highest notch in the cab latch.

    

29. Locate open area on cab floor reinforcement angle suitable for mounting air solenoid.

30. Mark and drill 1/4” thru hole and attach a three-way air solenoid to cab floor reinforcement angle as shown. Use #10- 32 x 1 1/2” long stainless steel bolt, washers, and nylock nut.

31. Connect 620531 three-way air solenoid harness to 620530 differential lock harness.

32. Secure wiring to nylon tubing and harnesses along route with tie straps. Ensure no chafing of wires.

33. Attach 3 ft. of 11003, black nylon tubing to supply side of solenoid and to exhaust side of solenoid.

34. Route exhaust tube down internal rail of floor towards rear of cab and secure in place.

35. Attach 30 ft. of 11000 yellow nylon tubing to delivery side of solenoid.

36. Remove one plug (40841) in air manifold.

37. Install 40887 90° elbow into an open port.

38. Route 11003, black tube, from the intake side of air solenoid to 40887 previously installed.

39. Tie strap nylon tube in place ensuring there will be no chafing or kinks.

40. Route 11000, yellow tubing, toward pivot of cab and secure in place.

41. Route 11000, yellow tubing, along the other nylon tubing, routed from cab to inside of frame rail. Continue routing tube toward rear of unit.

42. Route 11000, yellow tubing, across the air reservoir assembly in middle of frame and continue routing tubing down right-hand rail to the differential on rear axle.

43. Install 40861, 90° elbow, into port on a differential of the rear axle.

44. Attach 11000, yellow nylon tube, to previously installed 40861, trim excess tubing.

45. Secure tubing along route with double loop tie straps, ensuring that there is no chafing of tubing on components and there are no kinks along the route.

46. Lower cab.

47. Reinstall dash gauge panel and harness in the reverse order that it was removed in. Ensure no wires are crimped or removed from terminals during this process.

48. Start engine and allow air pressure to build to 125 PSI.

49. Depress treadle brake valve and shift unit into low gear.

50. Depress differential switch and test differential operation while unit is moving at low speeds. The shifting of the locking mechanism should be audible, slight turns may be necessary to fully engage differential lock. Axle should gain more traction, and steering radius will increase.

51. If differential fails to operate properly, inspect wiring and nylon tube routing for errors. Verify that the carrier was installed correctly per Meritor’s guidelines. Retest differential.

Note: Differential switch is a momentary type switch and must be held in the depressed position for differential to engage and remain engaged.

52. Secure all loose panels in place with #10 machine screws previously removed.

53. Remove “Lock Out, Tag Out” plaque.

54. Return vehicle to service.