Usage:
140G ( 5MD, 72V ) Motor Graders
- SUPPLEMENT: 08/26/91
Service Magazine; July 22, 1991; Page 5; "New Hydraulic Oil Temperature Switch Harness Assembly Used"; for 140G Motor Graders. Illustration 3 is incorrect. The correct illustration follows.
Illustration 3. Switch assembly connections AFTER modification.--------------- END SUPPLEMENT ---------------
Reference: Custom Product By Caterpillar, Supplementary Product Support Literature For 140G Motor Graders Equipped With 3Z4880 Modification And 3Z3580, 3Z4295, 3Z4350, 3Z4818, 3Z4877, 3Z4890, 3Z4930, 3Z4944, 3Z4945, 3Z4946, And/Or 3Z4951 Modifications, 140G All Wheel Drive (AWD) Motor Grader, SEBF0600-01, Page 30.
Description of Change: A new hydraulic oil temperature wiring harness assembly is used in the electronic monitoring system (EMS) wiring group. The new harness assembly connects a temperature switch assembly located in the hydraulic oil tank in SERIES with another temperature switch assembly located in a manifold near the hydraulic oil cooler. When the hydraulic oil reaches a specified temperature, the activated switch assembly will illuminate a warning lamp located on the EMS panel, alerting the operator of a change in operating condition. With the new harness assembly, actuation of either normally closed (N.C.) switch assembly will illuminate the warning lamp on the EMS panel.
The former harness assembly connected the temperature switch assemblies in PARALLEL. If operating conditions caused only one of the switch assemblies to activate, the warning lamp could not illuminate until the second switch assembly became activated. Due to the location of the switch assemblies and the design of the hydraulic system, the temperature of the oil in the tank and near the cooler could be different. If the implement hydraulic oil system overheats, and the AWD system is operating normally, the warning lamp could not illuminate. This could cause the hydraulic system and related components to overheat without the operator's knowledge.
Adaptable To: The new 1Q6257 Harness Assembly replaces the former 1Q5202 Harness Assembly (canceled) used in the 3Z4816 Monitor Wiring Group (not serviced as a group). This change is adaptable to first production. To adapt this change to an earlier machine, use the following procedure.
Procedure To Modify The Former 1Q5202 Harness Assembly In Earlier Machines
1. Open the disconnect switch.
2. Remove black 201U wire (B) from the switch assembly located at the hydraulic oil tank. See Illustration 1.
3. Remove yellow 404D wire (F) from the switch assembly located at the manifold near hydraulic oil cooler (E).
4. Protect both wires to prevent electrical shorts and secure them to the former wiring harness.
Illustration 1. Side view of 3Z4816 Monitor Wiring Group. (A) Former 1Q5202 Wiring Harness. (B) Black 201U wire (disconnect, insulate, and secure to harness assembly). (C) Hydraulic oil temperature switch assembly (tank). (D) Operator position. (E) Hydraulic oil cooler. (F) Yellow 404D wire (disconnect, insulate, and secure to harness assembly). (G) Hydraulic oil temperature switch assembly (cooler).
5. Make up a 16 gauge AWG wire 5300 mm (210 in) long. Install a 5200 mm (205 in) long 5P5984 Loom over the length of the wire. Install a 2L8075 Terminal on each end of the wire.
6. Connect one end of the new wire to the switch assembly on the hydraulic tank (C), and route the wire along former wiring harness (A). Connect the remaining end to the switch assembly located near the hydraulic oil cooler (E). Secure the wire to the harness at sufficient intervals. Illustrations 2 and 3 show the switch assembly connections before and after the modification.
Illustration 2. Switch assembly connections BEFORE modification.
Illustration 3. Switch assembly connections AFTER modification.
7. Close the disconnect switch.