CX28 Transmission For Combat and Tactical Vehicles Transmission ; Transfer Case Electronic Control System Caterpillar

• Perform the procedure after installing a new transmission.

• Perform the procedure after replacing the ECU.

• Perform the procedure after exchanging the ECU from one machine to another machine.

• Perform the procedure after replacing or servicing any of the transmission clutches, seals, pumps, etc.

Transmission Calibration

Illustration 1	g01370834

Note: The following procedure will require the machine to be driven. Shifting will be harsh at the beginning of the procedure. The quality of the shifts will improve throughout the calibration of the transmission. The quality of the shift will stabilize to a consistent level as the calibration is completed.

1. Verify that the fluid in the transmission is at the correct level. The transmission fluid level test is a manually initiated operation. The results are indicated on the gearshift selector. The operator may initiate the fluid level test after the following conditions are met. The vehicle must be level, stationary, and idling. The vehicle must also have a transmission fluid temperature of 80° C (176° F)at a minimum. Perform the following actions in order to initiate the test. Simultaneously press the up arrow and the down arrow. Simultaneously release the up arrow and the down arrow. The gearshift selector will count down from 24. The results are displayed when the count is complete. The table below shows the possible readings and the descriptions.
   Show/hide table

   Table 1

   Display	description
   "OL-LO-##"	Oil level is low by "## "quarts.
   "OL-HI-##"	Oil level is high by "##" quarts.
   "OL-OK"	Oil level is correct.

2. Connect and open the Caterpillar Electronic Technician (Cat ET). Confirm a J1939 connection.

3. Click "Configuration" on the menu bar. Select "Vehicle Configuration Parameters" from the options on the left side. Click "Transmission Calibration Configuration" from the drop-down list.

4. Program the calibration to "All Clutches". See figure 1 for more information.

5. Cycle the power to the ECU. Turn the key start switch from the ON position to the OFF position. Now, turn the key start switch to the ON position.

6. Verify that the oil temperature of the transmission is in a normal range. A normal range is above 60 °C (140 °F) and below 100 °C (212 °F). The calibration will not begin until the oil temperature reaches 60 °C (140 °F).

7. Complete this step before leaving the lot. With the parking brake RELEASED and the service brake APPLIED, shift the transmission from NEUTRAL to DRIVE. Shift the transmission from NEUTRAL to REVERSE. Repeat these shifts until there is no noticeable change in quality of the shift or a minimum of five times. You may leave the lot once this step is completed.

   Note: See this note for the CX35 only when the feature for starting in an alternate gear is programmed to 2. The Alternate Start Gear function will shift the transmission from first gear to second gear when drive is selected on the shifter. The feature will resume normal operation after the calibration procedure is completed.

8. Move the vehicle to a safe place. Accelerate the machine up to the second gear for the CX28 and the CX31. Maintain the engine speed at 1200 to 1300 RPM. A series of shifts from second gear to first gear will be performed by the transmission in four second intervals. Do NOT release the throttle. Maintain this condition until the shifts have stopped. Repeat these shifts until there is no noticeable change in the quality of the shifts or for a minimum of three times.

9. With both of the brakes RELEASED, perform the following shifts to the transmission and allow the machine to move. Sustain the throttle at approximately fifty percent and perform the shifts. Upshift the transmission from first gear through fifth gear for the CX28 and the CX31. Upshift the transmission from first gear through seventh gear for the CX35.

10. Downshift the transmission from fifth gear through first gear while the machine is coasting for the CX28 and the CX31. Downshift the transmission from seventh gear through first gear while the machine is coasting for the CX35. Braking slightly is permitted.

    Note: Avoid using all of the brakes or retarders.service brake, hydraulic retarder and engine brake.

11. Perform shifts from fifth gear to fourth gear by stepping through the shift for the CX28 and the CX31. This type of shift is achieved by accelerating the transmission to the fifth gear. The machine will downshift to the fourth gear during the acceleration. Allow the vehicle to coast in the fifth gear to the shift point from fifth gear to fourth gear. Do not apply the throttle. The range for the shift point is 1200 to 1400 RPM on an engine that has a 1200 RPM peak torque. The range for the shift point is 1300 to 1600 RPM on an engine that has a 1440 RPM peak torque. Repeat these shifts until there is no noticeable change in the quality of the shifts or for a minimum of five times.

Note: If the quality of shifting remains poor after this procedure, refer to the Troubleshooting, "Symptom Troubleshooting" section for more information.