Selection Of Service Harness For Engines With Electronic Ignition System{1408} Caterpillar

Introduction

This special instruction provides essential information in order to select a proper service harness for a particular G3500 Engine with an Electronic Ignition System (EIS).

This special instruction also provides listings of applicable hardware, tools, and procedures and contains helpful hints used in the installation of the service harness. It is very important that the information contained here is fully understood before attempting an installation. It should also be understood that due to the many varied engine wire configurations, it is not possible to write procedures that explain in detail every possible option. Therefore, these procedures should be viewed as general in nature with possible gaps in the sequence.

Selection Of Service Harness

Many optional features have been provided for the G3500 Engines. Each of these features may require additional wires within the original harness. It is not possible to provide a service harness that will match all different combinations of options. In an attempt to minimize the total number of harnesses and to meet as many applications as possible it has become necessary to group all wires into four main engine categories. The four categories are:

* Electric Power Generation (EPG)

* Industrial

* Landfill

* CoGen

Each category contains wiring for its most used options while excluding those wires of its least used options. As a result, any given service harness may contain unused wires and connectors while, at the same time, require the customer to provide custom wiring for the lesser used options. The following is a listing of items that are not supported with a service harness.

* Electric Starter

* Alternator

* Water Level Alarm Switch

* Left Hand Air Starter

* Digital Voltage Regulator

Each of the four G3500 harness categories identifies a service harness for a particular application. To determine which part number is needed, refer to Chart 1 entitled "Service Harness Part Numbers And Engine Categories".

Determination Of Service Harness Design

G3500 EIS engines were built with two slightly different harness designs. The two designs are differentiated by the terms "early build" harnesses and "current production" harnesses. Chart 2 entitled "Serial Numbers And Service Harness Designs" indicates the serial numbers appropriate for the G3500 EIS Engines and the two unique harness designs.

Selection Of Miscellaneous Parts Kit

A 131-2217 Harness Parts Kit of miscellaneous hardware pieces has been provided for all "early build" harnesses. This kit is needed only for "early build" harnesses and is not required when servicing harnesses on engines with serial numbers larger than those listed in Chart 2.

Chart 3 entitled "Miscellaneous Parts For 131-2217 Harness Parts Kit" shows a complete listing for all parts found in 131-2217 Harness Parts Kit.

Optional Hardware

As indicated above, the electric starter and alternator wires are not supplied with the service harness. Therefore, if this option is part of the original engine installation, then custom wires must be provided, power distribution box and its contents must be removed, and starter solenoid switch must be relocated. Refer to Chart 4 entitled "Optional Hardware" in order to locate the appropriate optional parts. It should also be understood that the type of optional hardware chosen will have an outcome on the required amount of custom wiring. For a better understanding, refer to the Installation Procedures (Steps 9-11) in this Special Instruction and compare them to 121-0121 Wiring Diagram (Page 10) and 4P-9570 Wiring Diagram (Page 11).

Installation Procedures

G3500 EIS service harnesses have many design features not found in earlier harnesses. For "early build" engines the installation of this service harness will update the electrical system with many of the latest improvements. Items such as new wire identifications will identify each individual wire as to its circuit function and its termination point within the engine-mounted terminal box. This will prevent the constant need to refer to a circuit diagram when connecting wires. It will also minimize the potential for wiring errors.

Harness routing has become more direct and, as the result, has become easier to install. Illustration 1 entitled "Engine Harness Routing" provides four views of the engine harness routing.

Illustration 1. Engine Harness Routing: (1) Front view. (2) Rear view. (3) Left side view. (4) Right side view.

Harness wires within the engine-mounted terminal box have been preformed to fit and, upon initial installation, will fall near the termination points. Other new features of interest include the removal of the power distribution box, termination of the manifold air pressure sensor (MAPS) to the engine-mounted terminal box, addition of a second magnetic pickup for governor control, addition of a second E-Stop contact, and installation of starter solenoid switch within the engine-mounted terminal box.

A successful installation of the service harness depends greatly on the repair person's overall understanding of the entire procedure. The step-by-step procedures are provided as a general guide through the replacement process. As stated above, the procedures can in no way provide complete detail of all situations. The procedures are as follows:

1. Shut off the main gas valve.

2. Completely isolate all electrical power sources, battery chargers, batteries, and other electrical power and control signals from the engine wiring by disconnecting both the positive and negative leads.

3. Using the appropriate tool, remove each engine harness wire lead from the terminal blocks found within the engine-mounted instrument panel. DO NOT remove any of the interconnect harness leads.

Chart 5 entitled "Early Production Wire Removal And Service Harness Replacement Cross-Reference" provides identifications for the correct removal of wires on the third column marked "Early Production Wire Ident." and respective terminal numbers on the second column marked "Terminal No.". This chart lists every all wiring options. It should be understood that any single engine arrangement may not contain all wires listed. Also, as a general rule, most wires to be removed will be located on the right hand side of the right column of terminals and on the left hand side of the left column of terminals.

4. Remove and store in a safe place all four screws, washers, and nuts used to mount the DDT connector. Remove the connector and attached wires and discard. A new connector with wires are provided in the service harness.

5. After disconnecting all engine harness wires from the instrument panel terminal strip, cut all associated nylon tie straps and disconnect all connectors inside the engine-mounted terminal box. Carefully remove and store in a safe place for later installation of the plate-mounting screws, nuts, and washers holding the cable grip bushing, lock nut, and cable onto the instrument panel bottom.

6. Remove the engine harness from the panel.

7. Remove all nylon tie straps from the various clipping locations along the engine-mounted ignition and safety harnessing.

NOTE: It is not necessary to remove the exhaust port temperature probes and pyrometer harness nor is it necessary to remove the engine-mounted instrument panel from the side of the engine.

8. Disconnect the engine harness from each sensor connector.

9. For "early build" harnesses it may be desirable to remove the power distribution box and mounting bracket from the left hand pan rail of the engine.

* If removal of the power distribution box and mounting bracket is desired, remove the four mounting bolts from the engine pan rail. Replace these four bolts with shorter OT-0065 Bolts provided with the miscellaneous parts kit. Before discarding the power distribution box, remove the starter solenoid switches and its mounting bolts. Store these components in a safe place for later mounting within the engine-mounted instrument panel. Discard the bracket and box with all remaining internal components.

* If removal of the power distribution box and mounting bracket is NOT desired, then custom wiring, in addition to the service harness, will be required. Refer to 4P-9570 Wiring Diagram (Pages 2 and 11) for starter/alternator wiring configurations, 121-0121 Wiring Diagram (Page 10), and Step 18 of this Special Instruction. DO NOT remove the wires terminated between the distribution box and the electric starters. DO NOT remove the starter solenoid switches from the distribution box. DO remove all old engine harness wires entering the box and distribution box mounted circuit breakers. At this point, there should be starter wires emitting from the right side of the distribution box but no wires emitting from the left side of the box.

10. All engine wiring should now be completely loose. Discard the old engine harness.

11. If the engine has been equipped with an ammeter it is recommended to remove the ammeter.

NOTE: This ammeter carries full current and if connected incorrectly would instantly destroy harness wires when power is applied.

Remove the ammeter and replace it with 118-7862 Gauge Assembly. See 112-0121 Wiring Diagram (Pages 10 and 11) for current production starter/alternator wiring configurations and 112-0121 Wiring Diagram (Pages 3 and 11) for voltmeter wiring information.

12. Refer to Illustration 1 for new locations of all mounting clips and harness routing. Where required, move the old clips to new locations. Additional clips, bolts, washers, and other components are provided in 131-2217 Harness Parts Kit to complete this job.

The new service harness must be routed as shown in Illustration 1. Proper routing is necessary for a correctly fitting harness.

13. It is required to punch several holes in the engine-mounted instrument panel. These holes are to be used for routing wires and mounting clips. Refer to Illustration 2 entitled "Front View Of Engine-Mounted Instrument Panel" and Illustration 4 entitled "Side View of Engine-Mounted Instrument Panel" for the size and location of mounting holes, clips, and rubber grommet. Carefully locate and punch all holes. Mount all components as shown on the illustrations.

Illustration 2. Front View Of Engine-Mounted Instrument Panel: (A) 54.5 mm (2.15 in). (B) 77.0 mm (3.03 in). (C) 66.7 mm (2.63 in). (5) Current production starter solenoid switch location. Mount on 1/4-20 inch bolts, 1/4 inch long. (6) 111-1323 Contact Block. (7) 111-1324 Contact Block. (8) 4P-8134 Clip.

Illustration 3. Terminals: (9) 9X-9675 End Bracket. (10) 9X-9677 End Cover. (11) 9X-9616 End Cover. (12) 108-1702 Single Terminal. (13) 115-2538 End Cover. (14) 116-5140 Double Terminal. (15) 114-1143 Circuit Breaker Assembly. (16) 116-7654 Circuit Breaker Assembly. (17) 116-5193 End Cover. (18) 116-5142 Double Isolated Terminal. (19) 116-7655 Circuit Breaker Assembly or 107-5857 Circuit Breaker Assembly. (20) 116-5137 Spacer.

Illustration 4. Side View Of Engine-Mounted Instrument Panel: (21) 5M-2894 Hard Washer. (22) OS-1594 Bolt (3/8-16 inch). (23) 4P-8134 Clip. (24) 4P-8134 Clip. (25) 5P-9135 Grommet.

14. Several terminals within the engine-mounted terminal box must be changed and/or moved to new locations to meet the various needs of the service harness. Refer to Illustration 2 and Illustration 3 entitled "Terminals" for visual aids while stepping through the following procedure.

* Remove and discard fuse block F1.

* Install CB3 16 ampere EIS 114-1143 Circuit Breaker Assembly above the bottom end bracket of the left hand rail. Battery power (+24 volt) must be supplied to this breaker by no less than a 12-gauge stranded copper wire. If electric starter and/or alternator options are required, then it will be necessary to install both circuit breaker 1 (CB1) and circuit breaker 2 (CB2). See Chart 4 for Caterpillar part numbers.

* Install a second 9X-9675 End Bracket at the top of the left hand column of terminals as shown in Illustration 3.

* Remove the interconnect wires from terminals 201, 202, 203, and 204 found at the bottom right hand column of terminals.

* Remove terminals 201, 202, 203, 204 and install them at the top left hand column; above the newly installed end block. Install protective 9X-9677 End Cover at the open end of the terminals. Install another end bracket above the cover. The end bracket should hold all terminals snugly.

* Extend sufficiently the interconnect wires, previously removed from 201 through 204, for termination at the new location.

NOTE: DO NOT reverse the leads. The copper shield must be terminated at 202; the red lead at 203; and the black lead at 204. Terminal 201 is not used.

This step will require 116-7648 Cable Assembly, three 2H-7648 Butt Splices, and 5P-1038 Heat Shrinkable Tube. For best electrical and mechanical properties the butt splices should be both crimped and soldered as shown in Illustration 5 entitled "Typical Shield Termination".

Illustration 5. Typical Shield Termination: (26) Circuit Identification Prefix "A330". (27) 2H-2965 Wire Splice. (28) 116-7648 Cable Assembly. (29) 5P-1038 Heat Shrinkable Tube. Terminal Number Identification Suffixes: (30) "T202". (31) "T203". (32) "T204".

* Remove and discard terminals 205, 206, and 207.

* Install three 116-5142 Double Isolated Terminals with 116-5137 Spacer and 116-5193 End Cover in place of 205, 206, and 207 along with both end plates at the bottom of the right hand column of the terminals.

* Slide all right hand connectors snugly down against the bottom end block.

* Remove and discard terminals 260 through 267 and the top end plate.

* Replace terminal 260 through 267 with 116-5140 Double Terminal and 115-2538 End Cover.

* Install 108-1702 Single Terminal 270 through 273 at the top of the right hand terminal column.

* Position top 9X-9616 End Cover and bracket snugly against terminal 273.

* If used, install the voltmeter gauge group at the same location as where the ammeter was previously mounted.

* Remove the old E-stop contact block and switch operator. Replace it with new 109-6507 Operator Switch, 111-1323 Contact Block, and 111-1324 Contact Block.

NOTE: When attaching wires to each contact block care must be taken to connect each wire to its respective terminal number. Refer to Chart 5 or 121-0121 Wiring Diagram for correct wiring.

15. Route the new service harness as shown on the harness drawing. Pull excess harness length tight between clips. Securely attach it with a nylon tie strap. Adjust clipping and positioning of the harness in order to allow the harness to touch only at each mounting clip and mating connector. Ideally, the harness should not be in contact with any other engine part.

16. Carefully feed the harness through the opening located on the engine-mounted terminal panel bottom and firmly hand-tighten.

NOTE: Do not remove the nylon tie straps used to bundle the harness wires. Each wire end has been cut to length, terminated, and bundled to allow it to fall on its respective termination point without excessive stretching or slackness.

17. Connect each wire end at its respective termination point by loosening each terminal screw clamping device. Insert wire end to its maximum depth. Each wire end should be held at that depth while tightening the terminal clamp. Lightly tug on each wire after clamping to determine if it is securely clamped.

NOTE: Each wire has been labelled with a circuit function code and termination point. As an example, the red wire labelled S111-T271 is known by the prefix "S111". It is also the MAP sensor +13 volt power; known by the suffix "T271" which is to be connected at terminal 271. All wires have been marked in this fashion. Therefore, connecting each wire by its labelled termination point can greatly facilitate the installation process. It is, however, highly recommended that wiring verification is performed. Refer to Chart 5 for a complete listing of service harness wire identifications and termination points. The exception to this rule has been noted with an asterisk (*).

One faulty connection could instantly destroy not only the newly installed service harness but other attached components as well. It is therefore vitally important that a careful check for possible cross-connections be performed before applying battery power. The most complete method for checking wire termination is to carefully compare each wire identification markings, wire color, and identification code with information provided in both Chart 5 and 121-0121 Wiring Diagram. As stated above, the suffix of each wire code is the terminal number to which it should be connected.

NOTE: The copper (Cu) colored wires are not copper in color. They have been electrically insulated with a green insulation material and are recognized as such.

18. If removal of the power distribution box is not desired, then custom wiring, in addition to the service harness, will be required. Refer to 4P-9570 Wiring Diagram (Pages 2 and 11) for the starter/alternator wiring configurations and 121-0121 Wiring Diagram (Page 10). Perform the following steps:

* From within the engine-mounted terminal box, disconnect wires P221-T209 and P320-T156. Insulate them with electrical tape and securely tie them with a nylon tie strap.

* Route a single 16-gauge stranded copper wire with red insulation from terminals 209 to the power distribution box starter solenoid switch (left field coil terminal).

* Route a single 16-gauge stranded copper wire with black insulation from the starter solenoid switch (right field coil terminal) to the negative battery terminal from within the power distribution box.

* Route a red 12-gauge stranded copper wire from CB3 (left side) to the positive battery post of the power distribution box.

* Route a single black 12-gauge stranded copper wire from terminal 5 (left side) to the negative battery post of the power distribution box.

19. If the engine is equipped with an EG-3P governor actuator with an early production harness, then it is necessary to change the actuator's connector from the three pin Sure-Seal to the Deutsch connector provided in the Kit. Pin assignment is found in Chart 6 entitled "EG-3P Connector Pin Assignment". For more information refer to 121-0121 Wiring Diagram (Page 3).

If the engine is equipped with both an Engine Status Control Module and 2301A Electronic Governor, then it will be necessary to install a second 8L-4171 Magnetic Speed Pickup supplied with the kit of parts. With the engine stopped, install the magnetic speed pickup into the rear flywheel housing's far left 5/8 inch threaded hole. Turn until the magnet core abuts the flywheel gear tooth. Then, back out the magnetic pickup 180 ± 40 degree. Install 4B-4171 Washer and the locking nut to 45 ± 7 N·m (33 ± 5 lb ft). Gear tooth to pickup clearance should be 0.70 ± 0.14 mm (0.028 ± 0.006 in).

20. Connect all remaining sensors at harness extremes.

21. Upon a thorough check of all connections attach the Digital Diagnostic Tool to the DDT connector located on the engine-mounted terminal box bottom plate. Apply 24 volt power. Correct fault codes as needed. All service harness wiring is now complete.