Installation Of The Transmission Output Speed Sensor{3141, 3175} Caterpillar

Wheel Loader:

994 (S/N: 9YF1-UP)

994D (S/N: 3TZ288-UP)

994F (S/N: 4421-UP)

Off-Highway Truck/Tractor:

785C (S/N: 5AZ1-UP)

789B (S/N: 7EK1-UP)

789C (S/N: 2BW1-UP)

793B (S/N: 1HL1-UP)

793C (S/N: 4AR1-UP; 4GZ1-UP; ATY1-UP; CBR1-UP)

Introduction

The ""Remove The Old Sensor" " section of this Special Instruction applies to the transmissions or the torque converters with the 144-0178 Speed Sensor or the 3E-6955 Speed Sensor .

If the 266-8576 Speed Sensor is already installed, proceed to ""Install The New Sensor" ".

Important Safety Information

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth level surface. Lower the bucket and or attachments to the ground. Stop the engine and engage the parking brake. Block the wheels and install the steering frame lock. Turn the battery disconnect switch to the OFF position and remove the key. Place a Special Instruction, SEHS7332, "Do Not Operate" tag at the battery disconnect switch location to inform personnel that the machine is being worked on.

Remove The Old Sensor

Note: When you replace the old sensor, first disconnect the connector to the speed sensor in order to identify the wires that go to each pin. The wire connections may not be obvious since the wires are potted. In order to reduce the chance for error, cut one wire at a time. Perform a continuity check between the cut wire that is connected to the old connector and the pin on the old connector. Insert one wire at a time into the new connector before going on to the next wire.

1. On the mating harness connector, identify the wire that is connected to pin A on the old sensor. Identify the wire that is connected to pin B on the old sensor. Identify the wire that is connected to pin C on the old sensor. Refer to Illustration 1. Record each wire color and each wire number.

   1. Label each wire.

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Illustration 1	g01223536
Old 144-0178 Speed Sensor

2. Disconnect the connector and remove the existing 144-0178 Speed Sensor or the 3E-6955 Speed Sensor .

3. Cut off the existing circular mating harness connector.

4. Strip off 6 mm (0.250 inch) to 8 mm (0.312 inch) of insulation from each wire.

5. Crimp a 9X-3402 Socket onto each wire with the 1U-5804 Crimping Tool .

6. Install each harness wire into the DT connector that is included in the 155-2260 Kit . Refer to Table 1.

   Note: The orientation of the pins are different on the new DT connector. Refer to Illustration 2.

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   Table 1

   Wire	Connector
   A	Pin A (Power)
   B	Pin B (Return)
   C	Pin C (Signal)

Note: The orientation of the pins on the new DT connector is different.

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Illustration 2	g01223608
New 266-8576 Speed Sensor (1) Jam Nut

7. Insert the green wedge from the 155-2260 Kit into the DT connector.

Install The New Sensor

1. Assemble the 133-1207 Washer and the 8L-2786 O-Ring onto the new 266-8576 Sensor .

   Note: Assemble the 133-1207 Washer onto the new 266-8576 Sensor before the 8L-2786 O-Ring .

2. Install the 266-8576 Sensor on the transmission or the torque converter. Screw in the sensor until the sensor makes gentle contact with internal gear. Back out the sensor "2/3" of a turn. Tighten the jam nut (1) to 25 ± 5 N·m (18 ± 4 lb ft).

3. Plug the mating harness connector into the connector for the 266-8576 Sensor . Ensure that the locking tab is secure.

   Secure the harness no more than 104 mm (4 inches) from the sensor. Use the 130-5300 Mounting Clip and the 3S-2093 Cable Straps in order to secure the connector and the harness.

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NOTICE
Do not stress the lead or have less than 10 mm (.4 inch) bend radius on the leads as the leads exit the sensor body.

Note: The 130-5300 Mounting Clip and the 3S-2093 Cable Straps are not included in the kit.

4. Calibrate the sensor per standard testing and adjustment procedures. Ensure that no fault or event codes were generated. If fault codes still occur, verify that the wiring of the connector is correct.