Procedure to Improve AC Inverter Cabinet Motor Control and ECM Wiring on Certain 794 AC Off-Highway Trucks {1408, 1421, 4822, 7610} Caterpillar

Off-Highway Truck/Tractor

794 AC (S/N: MN51-UP; MT51-UP)

Introduction

New Motor Control ECM modules are now used for the machines listed. The new modules will replace modules that are obsolete.

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

Safety Section

Show/hide table

Do not operate or work on this product unless you have read and understood the instruction and warnings in the relevant Operation and Maintenance Manuals and relevant service literature. Failure to follow the instructions or heed the warnings could result in injury or death. Proper care is your responsibility.

Show/hide table

Failure to follow all safety guidelines prescribed in this document and by governing authorities and regulatory agencies may result in severe injury or death of personnel or machine damage.

Show/hide table

When removing a major component or attachment, ensure that it is properly blocked or secured before removing mounting hardware. An assembly that is disconnected without proper blocking may shift or fall, resulting in serious injury or death of personnel or machine damage.

Show/hide table

Personal injury or death can result from improper maintenance procedures. To avoid injury or death, follow the procedures exactly as stated below.

Show/hide table

Personal injury can result from improper handling of chemicals. Make sure you use all the necessary protective equipment required to do the job. Make sure that you read and understand all directions and hazards described on the labels and material safety data sheet of any chemical that is used. Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of chemicals.

Show/hide table

Climbing equipment may be required to access this service point. Refer to the Operation and Maintenance Manual, "Mounting and Dismounting" topic for safety information.

Show/hide table

Before servicing/performing maintenance on the machine, electrical power must be physically disconnected; battery plugs must be disconnected from the batteries, or the trailing cable must be unplugged, and warning tags and padlocks shall be applied by a certified electrician. Certified electricians shall perform or direct any electrical work, including any energized testing, repair work in controllers, motors, or other approved compartments, and shall insure that all compartments are properly closed and inspected prior to re-energization. All applicable lock out and tag out procedures must be followed.

Show/hide table

Do not operate the machine if any guards or covers are missing or inadequately secured. Personnel could be seriously injured or machine damage may occur.

Show/hide table

Observe the safe working load limits of all lifting and blocking devices and keep a safe distance from suspended/blocked loads. Personnel may be seriously injured or killed by falling loads.

Required Parts

Note: A length of 18 AWG wire (a minimum of 4 ft is recommended) is required to complete some of the connections for the new install.

Required Tools

Machine Preparation

Illustration 1	g06398223
Inverter Cabinet (Shown with all covers removed for illustration purposes only.) (A) Motor Control ECM 2 (B) Motor Control ECM 1

Review the information in this section for the proper steps required to remove and replace the Motor Control Electronic Control Modules.

Note: The Motor Control ECM modules are located in the top right compartment of the Inverter Cabinet. See Illustration 1 for location. (Cabinet is shown with all covers removed.)

Procedure

Removal of Modules

1. Remove the top right cover from the inverter cabinet. Retain the cover and hardware used to secure the cover.
   Show/hide table

   Illustration 2	g06398260
   Motor Controller ECM Cabinet Location (A) Motor Control ECM 2 (B) Motor Control ECM 1

2. Identify the Motor Control 1 (B) or Motor Control 2 (A) module locations inside the top right section of the inverter cabinet. (See Illustration 2.)

3. Remove the faulty Motor Control ECM module or modules from the cabinet, using the following steps.
   Show/hide table

   Illustration 3	g06391589
   Typical front view of the Motor Controller ECM module and connector (C) J2 connector (D) J1 connector (E) Ground Strap (F) Mounting Bolt

   1. Remove the J2 connector (C) (front connector) from the ECM. Use suitable tooling to remove the J2 connector (C) and J1 connector (D) from the faulty ECM.

   2. Disconnect the ground strap (E) on the left side of the module.

   3. Remove the four mounting bolts (F) securing the ECM. The control module can now be removed. Retain the mounting bolts and isolation mount pieces.

      Note: Do not secure the J2 connector to the new module or modules, wires will need to be removed from the ECM connector to complete the installation. Set the Allen screw for the J1 connector but DO NOT tighten the screw.

   Show/hide table

   Illustration 4	g06398336
   The Terminal Blocks (G) are located inside the top left panel of inverter cabinet.

4. Remove the top left cover from the inverter cabinet. This section of the inverter cabinet contains the terminal blocks (G) that connect to each of the Motor Control ECM's. Retain the cover and hardware used to secure the cover.

Installation of New Modules

The next steps in the installation of the ECM involve attaching multiple wires to shorting plugs to combine voltage source and ground connections. The wires to be connected are listed at the end of this media. The information that follows is a general guideline for removing wires from the current locations.

Show/hide table

Illustration 5	g06391650
A6:P1 module installed (2) 6-pin plug for shields from J1 gray shorting plug (installed) (3) 12-pin plug for shields from J2 gray shorting plug (installed) (D) J1 Connector (Rear) (C) J2 Connector (Front) (H) Excess 24 volt wires removed (not tied back)

1. Use the tables at the end of this media to identify the wires to be removed from each ECM connector and the terminal block. Use the Wire Removal Tool 151-6320 to remove the wires from the 70-pin connector. Review the appropriate table to locate and install the wire at the designated pin location at the shorting plug.

   Note: When removing wires from a terminal block on the left side of the inverter cabinet (see Illustration 4 for location), follow the procedure (below) to avoid damaging the connector locations.

   Note: Wires at the terminal block are held in place using a spring contact. Approximately 10 lb of force is required to release the wire.

   Show/hide table

   NOTICE
   Damage to the wire or connector may occur if the wire cannot be removed easily.

   Show/hide table

   Illustration 6	g06391635
   Illustration of Terminal Block, on the left side of the Inverter Cabinet. Note: All four points are connected vertically, jumper bridge horizontally.

2. Insert the small, flat blade of the screwdriver (See Illustration 4) into the square hole below the wire terminal block to release the wire above.

3. Confirm that the correct wire was removed from the terminal block. Measure the continuity of the wire from the ECM to the terminal block.

4. If the correct wire has been disconnected, cut and tie back

Illustration 7	g06391662
This illustration shows the completed wire removal for Terminal Block 1B. Note wires circled (in red) on left side of image.

Shorting Plug connection locations for the Left Motor Controller ECM (MC1) in the Inverter Cabinet.

List of Specific Wire Changes for Installation

Changes to the Left Motor Controller ECM (MC1) Module

Shorting Plug #1 (6-pin Deutsch Connector) MC1

Note: The wires listed in Table 3 will be connected to a Receptacle Assembly (5). After all the wires are installed at the receptacle, the receptacle is plugged into the Connecting Plug Kit (6-pin) (3).

Shorting Plug connection locations for the Left Motor Controller ECM (MC1) in the Inverter Cabinet.

Note: To complete the electrical circuit connections for Shorting Plug #1, a new wire is required. Insert the new wire (SP1 J1-28) between the J1-28 pin location on the ECM connector and pin 5 on Shorting Plug #1.Use a length of 18 AWG wire to connection Pin J1-28 to Pin 5 on Shorting Plug #1. Connect a Connector Socket (16-GA to 18-GA) (6) at each end of the wire. Attach one end of the wire to Pin J1-28 at the ECM and the other end to Pin 5 at Shorting Plug #1.

Refer to the tables below for the remaining circuit connection changes, related to the shorting plugs for the Left Motor Controller ECM (MC1):

Wire Installation Locations

Install the wires extracted from the ECM at the following locations:

• Install Wire Number "RTDM11G" at pin 1 of Shorting Plug #1

• Install Wire Number "RTDM12G" at pin 2 of Shorting Plug #1

• Install Wire Number "RTDM13G" at pin 3 of Shorting Plug #1

• Install Wire Number "RTDM14G" at pin 4 of Shorting Plug #1

Shorting Plug #2 (12-pin Deutsch Connector) MC1

Note: The wires listed in Table 4 will be connected to a receptacle assembly (4). After all the wires are installed at the receptacle, the receptacle is plugged into the Connecting Plug Kit (12-pin) (2).

Shorting Plug connection locations for the Left Motor Controller ECM (MC1) in the Inverter Cabinet.

Note: To complete the electrical circuit connections for Shorting Plug #2, a new wire is required. Insert the new wire (SP2 J2-65) between the J2-65 pin location on the ECM connector and pin 12 on Shorting Plug #2.Use a length of 18 AWG wire to connection Pin J2-65 to Pin 12 on Shorting Plug #2. Connect a Connector Socket (16-GA to 18-GA) (6) at each end of the wire. Attach one end of the wire to Pin J2-65 at the ECM and the other end to Pin 12 at Shorting Plug #2.

Refer to the tables below for the remaining circuit connection changes, related to the shorting plugs for the Left Motor Controller ECM (MC1):

Wire Installation Locations

Install the wires extracted from the ECM at the following locations:

• Install Wire Number "IV1 (SH-DR1)" at pin 1 of Shorting Plug #2

• Install Wire Number "GU1 (SH-DR)" at pin 2 of Shorting Plug #2

• Install Wire Number "IW1 (SH-DR1)" at pin 3 of Shorting Plug #2

• Install Wire Number "GW1 (SH-DR)" at pin 4 of Shorting Plug #2

• Install Wire Number "GV1 (SH-DR)" at pin 5 of Shorting Plug #2

• Install Wire Number "GX1 (SH-DR)" at pin 6 of Shorting Plug #2

• Install Wire Number "GY1 (SH-DR)" at pin 7 of Shorting Plug #2

• Install Wire Number "GZ1 (SH-DR)" at pin 8 of Shorting Plug #2

• Install Wire Number "ICR (SH-DR1)" at pin 9 of Shorting Plug #2

• Install Wire Number "GCM (SH-DR)" at pin 10 of Shorting Plug #2

• Install Wire Number "IU1 (SH-DRI)" at pin 11 of Shorting Plug #2

ECM Pin Location Changes for Left Motor Controller ECM (MC1)

The following wire relocation changes are required at the Left Motor Controller ECM (MC1) J2 harness connector.

ECM Wires to Remove (Leave Disconnected) for Left Motor Controller ECM (MC1)

Note: For each of the wires listed in Table 6, cut off the terminal.

ECM Wires to Remove (Leave Disconnected) for Terminal Block 1 B

Note: Measure the wire from end-to-end to verify that the correct wire was disconnected.

Changes to the Right Motor Controller ECM (MC2) Module

Note: The wires listed in Table 8 will be connected to a Receptacle Assembly (5). After all the wires are installed in the receptacle, the receptacle is plugged into the Connecting Plug Kit (6-pin) (3).

Shorting Plug connection locations for the Right Motor Controller ECM (MC2) in the Inverter Cabinet.

Shorting Plug #3 (6-pin Deutsch Connector) MC2

Shorting Plug connection locations for the Right Motor Controller ECM (MC2) in the Inverter Cabinet.

Note: To complete the electrical circuit connections for Shorting Plug #3, a new wire is required. Insert the new wire (SP3 J1-28) between the J1-28 pin location on the ECM connector and pin 5 on Shorting Plug #3.Use a length of 18 AWG wire to connection Pin J1-28 to Pin 5 on Shorting Plug #3. Connect a Connector Socket (16-GA to 18-GA) (6) at each end of the wire. Attach one end of the wire to Pin J1-28 at the ECM and the other end to Pin 5 at Shorting Plug #3.

Refer to the tables below for the remaining circuit connection changes, related to the shorting plugs for the Right Motor Controller ECM (MC2):

Wire Installation Locations

Install the wires extracted from the ECM at the following locations:

• Install Wire Number "RTDM21G" at pin 1 of Shorting Plug #3

• Install Wire Number "RTDM22G" at pin 2 of Shorting Plug #3

• Install Wire Number "RTDM23G" at pin 3 of Shorting Plug #3

• Install Wire Number "RTDM24G" at pin 4 of Shorting Plug #3

Shorting Plug #4 (12-pin Deutsch Connector) MC2

Note: The wires listed in Table 9 will be connected to a Receptacle Assembly (4). After all the wires are installed in the receptacle, the receptacle is plugged into the Connecting Plug Kit (12-pin) (2).

Shorting Plug connection locations for the Left Motor Controller ECM (MC1) in the Inverter Cabinet.

Note: To complete the electrical circuit connections for Shorting Plug #4, a new wire is required. Insert the new wire (SP4 J2-65) between the J2-65 pin location on the ECM connector and pin 12 on Shorting Plug #4.Use a length of 18 AWG wire to connection Pin J2-65 to Pin 12 on Shorting Plug #4. Connect a Connector Socket (16-GA to 18-GA) (6) at each end of the wire. Attach one end of the wire to Pin J2-65 at the ECM and the other end to Pin 12 at Shorting Plug #4.

Refer to the tables below for the remaining circuit connection changes, related to the shorting plugs for the Left Motor Controller ECM (MC1):

Wire Installation Locations

Install the wires extracted from the ECM at the following locations:

• Install Wire Number "IV2 (SH-DR1)" at pin 1 of Shorting Plug #4

• Install Wire Number "GU2 (SH-DR)" at pin 2 of Shorting Plug #4

• Install Wire Number "IW2 (SH-DR1)" at pin 3 of Shorting Plug #4

• Install Wire Number "GW2 (SH-DR)" at pin 4 of Shorting Plug #4

• Install Wire Number "GV2 (SH-DR)" at pin 5 of Shorting Plug #4

• Install Wire Number "GX2 (SH-DR)" at pin 6 of Shorting Plug #4

• Install Wire Number "GY2 (SH-DR)" at pin 7 of Shorting Plug #4

• Install Wire Number "GZ2 (SH-DR)" at pin 8 of Shorting Plug #4

• Install Wire Number "IDC (SH-DR1)" at pin 9 of Shorting Plug #4

• Install Wire Number "GOV2 (SH-DR)" at pin 10 of Shorting Plug #4

• Install Wire Number "IU2 (SH-DRI)" at pin 11 of Shorting Plug #4

ECM Pin Location Changes for Right Motor Controller ECM (MC2)

The following wire relocation changes are required at the Right Motor Controller ECM (MC2) J2 harness connector.

ECM Wires to Remove (Leave Disconnected) for Right Motor Controller ECM (MC1)

Note: For each of the wires listed in Table 11, cut off the terminal.

ECM Wires to Remove (Leave Disconnected) for Terminal Block 1 B

Note: Measure the end-to-end continuity of the wires to verify that the correct wire is disconnected. Tape up ends of wire and tie wrap.

Note: Install the shorting mating connectors (5) to (6). Install the J1 and J2 connectors at the ECM module.

ECM Software Installation

Illustration 8	g06402489
The illustration shows the screen for beginning the process of programming the new ECM modules.

The Drivetrain ECM and A6:P1 Motor Control ECM modules must be flashed with new software to complete the installation. Reference Table 1 for the software part numbers specific to each module. Refer to Testing and Adjusting, UENR2480, Electronic Control Module (ECM) - Flash Program when flashing software for the ECM's.