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| Illustration 1 | g01412568 |
Schematic for the Power Train/Chassis Electronic Control Module | |
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| Illustration 2 | g01154121 |
The Power Train/Chassis Electronic Control Module (Power Train/Chassis ECM) is the main component in the power train electrical system. The Power Train/Chassis ECM is located behind the cover at the front of the cab. The Power Train/Chassis ECM has several input signals and output signals. Refer to illustration 1 on the previous page for the input signals and for the output signals.
The Power Train/Chassis ECM receives current through a circuit breaker on the dash panel. This current is used to energize the transmission hydraulic control modulating valves. These modulating valves control the direction and the speed. This current is also used to energize the torque converter lockup clutch modulating valve. This modulating valve controls the option of torque converter drive or the option of direct drive. The Power Train/Chassis ECM also controls the electrical system for the hoist, the retarder, and the parking brake.
The CatData Link is used to share information with other systems such as the Engine Electronic Control Module (Engine ECM) and the Caterpillar Monitoring System. Signals that are sent to the Engine ECM result in reduced engine speed during upshifts and increased engine speed during downshifts.
System Operation
| Operation of the Torque Converter for Transmission Speed | ||
| Transmission Speed | Torque Converter Drive | Direct Drive with an Engaged Lockup Clutch |
| Reverse | X | |
| Neutral | X | |
| First | X | X |
| Second | X | |
| Third | X | |
| Fourth | X | |
| Fifth | X | |
| Sixth | X | |
| Seventh | X | |
Neutral Start Control
The neutral start control ensures that the machine will only start in NEUTRAL. The Power Train/Chassis ECM receives a signal from the shift lever position sensor. When the shift lever is in the NEUTRAL position, the signal is grounded and the machine will start. If the shift lever switch is not in the NEUTRAL position, the ground is broken and the machine will not start. This will prevent the machine from being started in gear.
Note: The parking brake must also be engaged in order for the machine to start.
Neutral (Torque Converter Drive)
When the transmission shift lever is in the NEUTRAL position, the rotor for the shift lever position sensor is in the NEUTRAL position. With the shift lever position sensor in this position, a signal is sent to the Power Train/Chassis ECM. The Power Train/chassis ECM energizes transmission hydraulic control modulating valve for number four clutch. The transmission hydraulic control modulating valve sends hydraulic oil to number four clutch.
FIRST (Torque Converter or Direct Drive)
When the transmission shift lever is moved to the FIRST speed position, the rotor for the shift lever position sensor moves to the FIRST speed position. A signal is sent to the Power Train/Chassis ECM. This signal informs the Power Train/Chassis ECM that the shift lever position sensor is in the FIRST speed position.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number one clutch and number six clutch. The transmission hydraulic control modulating valves send hydraulic oil to number one clutch and number six clutch.
The machine is now in FIRST speed and the machine is in torque converter drive.
FIRST speed is converter drive at lower ground speeds. FIRST speed is direct drive at higher ground speeds. The transmission output speed sensors send a signal to the Power Train/Chassis ECM. This signal tells the Power Train/Chassis ECM the ground speed of the machine. When the ground speed reaches approximately 6 km/h (4 mph), the Power Train/Chassis ECM sends a signal to the torque converter lockup clutch modulating valve. When the lockup clutch modulating valve is energized, hydraulic oil pressure is applied to the torque converter lockup clutch. The machine is in FIRST speed and the machine is in direct drive.
The torque converter lockup clutch will stay engaged until there is an upshift, a downshift, or a decrease in ground speed. If there is sufficient decrease in ground speed and the machine is still in FIRST speed, the Power Train/Chassis ECM will de-energize the torque converter lockup clutch modulating valve. Hydraulic oil pressure to the lockup clutch will stop and the machine will return to torque converter drive.
Shifting Procedures
The following sections will explain the operations of automatic upshifts and automatic downshifts.
Automatic Upshift (FIRST to SECOND)
When the transmission shift lever is moved to the SECOND speed position, the rotor for the shift lever position sensor is turned to the SECOND speed position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that an upshift is needed. The upshift to SECOND speed from FIRST speed is automatic when the correct ground speed signal from the transmission output speed sensors is sent to the Power Train/Chassis ECM, and the transmission shift lever is in SECOND speed position or above SECOND speed position.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will decrease the engine speed during the upshift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number two clutch and number six clutch. The transmission hydraulic control modulating valves send hydraulic oil to number three clutch and number six clutch.
The Power Train/chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive SECOND speed.
Automatic Downshift (SECOND to FIRST)
When the transmission shift lever is moved to the FIRST speed position, the rotor for the shift lever position sensor turns to the FIRST speed position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that a downshift is needed. The downshift to FIRST speed from SECOND speed is automatic when the correct ground speed signal from the transmission speed sensors is sent to the Power Train/Chassis ECM.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The lockup clutch modulating valve is de-energized. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will increase the engine speed during the downshift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number one clutch and number six clutch. The transmission hydraulic control modulating valves send hydraulic oil to number one clutch and number six clutch.
The Power Train/Chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive FIRST speed.
Automatic Upshift (SECOND to THIRD)
When the transmission shift lever is moved to the THIRD speed position, the rotor for the shift lever position sensor is turned to the THIRD speed position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that an upshift is needed. The upshift to THIRD speed from SECOND speed is automatic when the correct ground speed signal from the transmission output speed sensors is sent to the Power Train/Chassis ECM, and the transmission shift lever is in THIRD speed position or above THIRD speed position.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will decrease the engine speed during the upshift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number two clutch and number six clutch. The transmission hydraulic control modulating valves send hydraulic oil to number two clutch and number six clutch.
The Power Train/Chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive THIRD speed.
Automatic Downshift (THIRD to SECOND)
When the transmission shift lever is moved to the SECOND speed position, the rotor for the shift lever position sensor turns to the SECOND speed position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that a downshift is needed. The downshift to SECOND speed from THIRD speed is automatic when the correct ground speed signal from the transmission speed sensors is sent to the Power Train/Chassis ECM.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The lockup clutch modulating valve is de-energized. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will increase the engine speed during the downshift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number three clutch and number six clutch. The transmission hydraulic control modulating valves send hydraulic oil to number three clutch and number six clutch.
The Power Train/Chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive SECOND speed.
Automatic Upshift (THIRD to FOURTH)
When the transmission shift lever is moved to the FOURTH speed position, the rotor for the shift lever position sensor is turned to the FOURTH speed position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that an upshift is needed. The upshift to FOURTH speed from THIRD speed is automatic when the correct ground speed signal from the transmission output speed sensors is sent to the Power Train/Chassis ECM, and the transmission shift lever is in FOURTH speed position or above FOURTH speed position.
The Power Train/Chassis ECM energizes the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch.
Note: The torque converter will not be in torque converter drive during this shift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number three clutch and number five clutch. The transmission hydraulic control modulating valves send hydraulic oil to number three clutch and number five clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive FOURTH speed.
Automatic Downshift (FOURTH to THIRD)
When the transmission shift lever is moved to the THIRD speed position, the rotor for the shift lever position sensor turns to the THIRD speed position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that a downshift is needed. The downshift to THIRD speed from FOURTH speed is automatic when the correct ground speed signal from the transmission speed sensors is sent to the Power Train/Chassis ECM.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will decrease the engine speed during the upshift.
The Power Train/Chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number two clutch and number six clutch. The transmission hydraulic control modulating valves send hydraulic oil to number two clutch and number six clutch. The machine is now in direct drive THIRD speed.
Automatic Upshift (FOURTH to FIFTH)
When the transmission shift lever is moved to the D (DRIVE) position, the rotor for the shift lever position sensor is turned to the D (DRIVE) position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that an upshift is needed. The upshift to FIFTH speed from FOURTH speed is automatic when the correct ground speed signal from the transmission output speed sensors is sent to the Power Train/Chassis ECM, and the transmission shift lever is in the D (DRIVE) position .
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will decrease the engine speed during the upshift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number two clutch and number five clutch. The transmission hydraulic control modulating valves send hydraulic oil to number two clutch and number five clutch.
The Power Train/Chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive FIFTH speed.
Automatic Downshift (FIFTH to FOURTH)
When the transmission shift lever is moved to the FOURTH speed position, the rotor for the shift lever position sensor turns to the FOURTH speed position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that a downshift is needed. The downshift to FOURTH speed from FIFTH speed is automatic when the correct ground speed signal from the transmission speed sensors is sent to the Power Train/Chassis ECM.
The Power Train/Chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed.
Note: The torque converter will not be in torque converter drive during this shift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number three clutch and number five clutch. The transmission hydraulic control modulating valves send hydraulic oil to number three clutch and number five clutch. The machine is now in direct drive FOURTH speed.
Automatic Upshift (FIFTH to SIXTH)
When the transmission shift lever is moved to the D (DRIVE) position, the rotor for the shift lever position sensor is turned to the D (DRIVE) position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that an upshift is needed. The upshift to SIXTH speed from FIFTH speed is automatic when the correct ground speed signal from the transmission output speed sensors is sent to the Power Train/Chassis ECM, and the transmission shift lever is in the D (DRIVE) position.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will decrease the engine speed during the upshift.
The Power Train/Chassis ECM energizes the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number three clutch and number four clutch. The transmission hydraulic control modulating valves send hydraulic oil to number three clutch and number four clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive SIXTH speed.
Automatic Downshift (SIXTH to FIFTH)
When the transmission shift lever is moved to the D (DRIVE) position, the rotor for the shift lever position sensor turns to the D (DRIVE) position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that a downshift is needed. The downshift to FIFTH speed from SIXTH speed is automatic when the correct ground speed signal from the transmission speed sensors is sent to the Power Train/Chassis ECM.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will decrease the engine speed during the upshift.
The Power Train/Chassis ECM energizes the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number two clutch and number five clutch. The transmission hydraulic control modulating valves send hydraulic oil to number two clutch and number five clutch. The machine is now in direct drive FIFTH speed.
Automatic Upshift (SIXTH to SEVENTH)
When the transmission shift lever is moved to the D (DRIVE) position, the rotor for the shift lever position sensor is turned to the D (DRIVE) position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that an upshift is needed. The upshift to SEVENTH speed from SIXTH speed is automatic when the correct ground speed signal from the transmission output speed sensors is sent to the Power Train/Chassis ECM, and the transmission shift lever is in the D (DRIVE) position.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will decrease the engine speed during the upshift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number two clutch and number four clutch. The transmission hydraulic control modulating valves send hydraulic oil to number two clutch and number four clutch.
The Power Train/Chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive SEVENTH speed.
Automatic Downshift (SEVENTH to SIXTH)
When the transmission shift lever is moved to the D (DRIVE) position, the rotor for the shift lever position sensor turns to the D (DRIVE) position. A signal is sent to the Power Train/Chassis ECM. The signal from the transmission output speed sensors will inform the Power Train/Chassis ECM that a downshift is needed. The downshift to SIXTH speed from SEVENTH speed is automatic when the correct ground speed signal from the transmission speed sensors is sent to the Power Train/Chassis ECM.
The Power Train/Chassis ECM de-energizes the torque converter lockup clutch modulating valve when a shift is necessary. The lockup clutch modulating valve is de-energized. The flow of hydraulic oil to the torque converter lockup clutch stops and the machine is in torque converter drive for a moment. At the same time, the Power Train/Chassis ECM sends a signal to the Engine ECM. The Engine ECM will increase the engine speed during the downshift.
The Power Train/Chassis ECM energizes transmission hydraulic control modulating valves for number three clutch and number four clutch. The transmission hydraulic control modulating valves send hydraulic oil to number three clutch and number four clutch.
The Power Train/Chassis ECM will then energize the torque converter lockup clutch modulating valve. The lockup clutch modulating valve will send hydraulic oil pressure to the torque converter lockup clutch. At the same time, the Power Train/Chassis ECM signals the Engine ECM to increase engine speed. The machine is now in direct drive SIXTH speed.
Directional Shift Management
Directional shift management reduces torque spikes in the transmission driveline. Directional shift management reduces the energy spikes of the transmission clutch. The transmission driveline is designed to withstand the torque converter stall. The torque converter stall is the maximum amount of torque that is sent to the transmission by the torque converter.
If the engine speed is above 1350 rpm and the operator shifts into the NEUTRAL position, through the NEUTRAL position, or out of the NEUTRAL position, spikes will be generated in the torque converter. The pressure of the spikes is greater than the levels of the torque converter stall. The Power Train/Chassis ECM stops the pressure spikes by delaying the shift. The Power Train/Chassis ECM then signals the Engine Electronic Control Module (Engine ECM) for a reduction of fuel and for a lowering of the engine speed. The Power Train/Chassis ECM then shifts to the requested gear. This reduces the stress on the driveline. This also prevents wear on the transmission and premature failure of the final drives or of the differentials.
The event will be recorded as an improper shift.
Shift Inhibiting
If the transmission is in any forward speed and the transmission shift lever is moved to the REVERSE position, the transmission will downshift to NEUTRAL as the ground speed decreases. When the ground speed decreases to approximately 5 km/h (3 mph), the transmission will make a shift into REVERSE from NEUTRAL.
Neutral Coasting
This function restricts the ability to coast into NEUTRAL from high speeds. This restriction extends the transmission life. The transmission speed sensors measure the rotation of the gear teeth on a gear that is fastened to the output shaft of the transmission. The Power Train/Chassis ECM uses this measured speed in order to determine the ground speed. If the measured speed is greater than 5 km/h (3 mph), the transmission will not shift into NEUTRAL.
Note: The operator can bypass the restriction against coasting into NEUTRAL. However, if the ground speed is greater than 12 km/h (7.5 mph) for more than 2.5 seconds, the event will be recorded in the Power Train/Chassis ECM. The Power Train/Chassis ECM will apply the retarder brakes in order to reduce the ground speed of the machine. Also, the Power Train/Chassis ECM will send a signal to the Engine ECM to increase the engine speed to 1350 rpm. This will increase the flow of lubrication oil to the transmission.