Prior to starting with checks on the modulating valves, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Specification, Systems Operation, Testing and Adjusting, M0090887, "Power Train Electronic Control System".
After checking for fault codes, run a calibration of the transmission. Refer to Specification, Systems Operation, Testing and Adjusting, M0090887, "Transmission - Calibrate".
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| Illustration 1 | g06305910 |
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Modulating valves (Electronic Clutch Pressure Control) (1) Pressure for clutch 3 (2) Pressure for clutch 1 (3) Torque converter inlet relief pressure (4) Pressure for clutch 5 (5) Pressure for clutch 4 (6) Pressure for clutch 2 | |
The pressure test points for the transmission clutches can be found back side of the "doghouse" as shown in Illustration 1. The modulating valves (electronic clutch pressure control) are located on the right side of the transmission.
With the transmission in neutral, the pressure of the oil in the transmission clutches can only be tested on clutch 1. Refer to Specification, Systems Operation, Testing and Adjusting, M0090887, "Power Train Pressures".
If the pressure for clutch 1 is correct, the oil supply to the modulating valves (electronic clutch pressure control) is sufficient.
The pressure in the other transmission clutches can only be tested with the output flange moving.
If the transmission is observed to slip in one gear, a transmission clutch may not be functioning correctly.
Use Table 1 in order to determine the transmission clutch that may not be functioning correctly.
| CX48-P2560-3060 Transmission Clutch Assignments | ||||||||
|---|---|---|---|---|---|---|---|---|
| Operation | Gear Ratios | CLUTCHES | Transmission Output Speed at 800 RPM Input with 5LUC Engaged (RPM) | Transmission Output Speed at 1900 RPM Input with LUC Engaged (RPM) | ||||
| 1 | 2 | 3 | 4 | 5 | ||||
| Stall | − | O | O | O | − | − | ||
| Park | − | O | O | − | − | |||
| Neutral | − | O | − | − | ||||
| 1 Forward | 3.339 | O | O | 240 | 569 | |||
| 2 Forward | 2.453 | O | O | 326 | 775 | |||
| 3 Forward | 2.200 | O | O | 364 | 864 | |||
| 4 Forward | 1.808 | O | O | 442 | 1051 | |||
| 5 Forward | 1.616 | O | O | 495 | 1176 | |||
| 6 Forward | 1.359 | O | O | 589 | 1398 | |||
Testing The Solenoid Coil Assembly
The function of the solenoids can be tested by running a calibration of the transmission. The ability to monitor pressures in the clutches when a calibration sequence is being run is possible. The calibration will also alert the operator to any faults that are detected with the transmission clutches.
Note: The pressures that can be observed during a calibration are not the full pressures of a clutch engagement. Use a
Run a calibration of the planetary transmission and observe the pressures of the oil in the clutches. Refer to Specification, Systems Operation, Testing and Adjusting, M0090887, "Power Train Pressures" and Specification, Systems Operation, Testing and Adjusting, M0090887, "Transmission - Calibrate".
Observe the pressure for each clutch. If a pressure rise is noted, the solenoid and the related electrical circuit are functioning.
If a pressure rise is not noted, there may be a fault with the solenoid or with the modulating valve.
This test is carried out in order to determine if the solenoid coil on the modulating valve is energized.
If a pressure rise is not noted, use a tag wire to check that the solenoid coil is energized. Solenoid coil is energized if the tag wire is attracted to the solenoid coil. The problem is in the solenoid cartridge. The problem could be a bent solenoid stem, a screen that is dirty or plugged, or a spring that is weak or broken. Repair the electronic clutch pressure control modulating valve or replace electronic clutch pressure control modulating valve.
If the tag wire does not indicate that the solenoid coil is energized, the problem is in the electrical circuit.
If the solenoid does not appear to function, disconnect the connector for the solenoid. Check the resistance of the windings of the coil in the solenoid.
The resistance of the windings in the solenoid should be 8.7Ω ± 0.4Ω.
Replace the solenoid if the resistance of the windings is outside the specifications.
Reference: For additional information about the electronic clutch pressure control modulating valves, refer to Specification, Systems Operation, Testing and Adjusting, M0090887, "Modulating Valves (Electronic Clutch Pressure Control)".
Reference: For additional information about electrical system troubleshooting, refer to Systems Operation, Troubleshooting, Testing and Adjusting, M0090895, "Power Train Electronic Control System".