R1600G Load Haul Dump Power Train Electronic Control System Power Train Electronic Control System Caterpillar

The main functions of the power train electronic control system follow: "Neutral Start Function", "Manual Shift Function", "Automatic Shift Function", "Transmission Neutralizer Function", "Parking Brake Function", "Backup Alarm Function", "Ride Control Function", "Lockup Clutch Function", "Dual Horsepower Function", "Remote Control Function" and "Diagnostic Operation".

Neutral Start Function

Show/hide table




Illustration 1	g01012599
Start relay

The start relay is an output of the Power Train Electronic Control Module (ECM). The start relay turns the start solenoid on and off. The start solenoid controls the starting motor. When the operator turns the key start switch to the START position and the Power Train ECM decides that all the starting conditions are satisfied, the Power Train ECM energizes the start relay with a +battery signal. The Power Train ECM will not allow the engine to be started unless the transmission direction and speed control is in the NEUTRAL position. The start relay allows the starting motor to turn. The Power Train ECM will not allow the starter to activate if the engine is running.

The start relay has a connector with two contacts. One contact receives power from connector contact J1-8 of the Power Train ECM. The other contact returns power to connector contact J2-3 of the Power Train ECM.

Terminal 3 of the start relay connects to a +battery source. Terminal 4 connects to the start solenoid.

ReferenceFor information on the key start switch, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Switches" for the machine that is being serviced.

ReferenceFor information on the Power Train Electronic Control Module (ECM), refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Electronic Control Module (Power Train)" for the machine that is being serviced.

Manual Shift Function

Show/hide table

Table 1
Solenoid Valve (Transmission Clutch)
Speed and Direction	Activated Solenoids
Fourth Speed Forward	3 and 2
Third Speed Forward	4 and 2
Second Speed Forward	5 and 2
First Speed Forward	6 and 2
Neutral	3
First Speed Reverse	6 and 1
Second Speed Reverse	5 and 1
Third Speed Reverse	4 and 1
Fourth Speed Reverse	3 and 1

STIC Steering

Show/hide table




Illustration 2	g01026232
(1) Upshift switch (2) Downshift switch (3) Transmission direction control switch

The STIC steering control is located in the operator station.

Show/hide table




Illustration 3	g01026233
(4) Autoshift control switch (5) MANUAL position

Shifting the transmission is the main function of the Power Train Electronic Control Module (ECM). The Power Train ECM receives a signal from autoshift control switch (4). The autoshift control switch sends a signal to the Power Train ECM for the desired shift mode, AUTO mode or MANUAL mode. In order to manually shift the transmission, the autoshift control switch must be in MANUAL position (5) .

Transmission direction control switch (3) is a three-position switch that selects either forward direction, neutral, or reverse direction.

The operator selects a direction by moving transmission direction control switch (3). The transmission direction control switch sends a signal to the Power Train ECM of the desired direction of travel.

The upshift switch and the downshift switch allow the operator to select the speed range of the transmission. Press upshift switch (1) in order to increase the speed of the transmission. The Power Train ECM will upshift the transmission to the next higher gear. Press downshift switch (2) in order to decrease the speed of the transmission. The Power Train ECM will downshift the transmission to the next lower gear. The upshift switch and the downshift switch have two input connections each at the Power Train ECM on connector J1.

Note: The correct status of the four input connections is required to allow the Power Train ECM to make each shift.

Note: The normally closed (N/C) circuit and normally open (N/O) circuit of the transmission downshift switch are used for diagnostic purposes. The normally closed (N/C) circuit and normally open (N/O) circuit of the upshift switch are used for diagnostic purposes. If the normally closed (N/C) circuit and normally open (N/O) circuit are open at the same time, the Power Train ECM records a fault. If the normally closed (N/C) circuit and normally open (N/O) circuit are grounded at the same time, the Power Train ECM records a fault.

When the key start switch is turned from the OFF position to ON position, the Power Train ECM is activated. When the Power Train ECM is first activated all of the clutch solenoid valves are de-energized. The clutch solenoid valves are de-energized regardless of the position of transmission direction control switch (3). The Power Train ECM then determines if transmission direction control switch (3) is in the NEUTRAL position. The Power Train ECM disables the transmission if the NEUTRAL position is not selected. If the transmission direction control switch is in the NEUTRAL position, the Power Train ECM selects the current speed and the direction as neutral.

In order for the transmission to operate, two transmission solenoid valves must be energized. When the transmission is in neutral, only one solenoid valve is energized. For more information on solenoid valves refer to Table 1.

For information on the shifting sequence of the transmission refer to Table 2.

Show/hide table

Table 2
Normal Shifting Sequence
Speed Range and Direction	REVERSE Position Transmission Shift	NEUTRAL Position Transmission Shift	FORWARD Position Transmission Shift	UP SHIFT Position Transmission Shift	DOWN SHIFT Position Transmission Shift
4F	4R	Neutral ⁽¹⁾ (4N)	No Change	No Change	3F
3F	3R	Neutral ⁽¹⁾ (3N)	No Change	4F	2F
2F	2R	Neutral ⁽¹⁾ (2N)	No Change	3F	1F
1F	1R	Neutral ⁽¹⁾ (1N)	No Change	2F	No Change
Neutral ⁽¹⁾ (1N, 2N, 3N, 4N)	Last ⁽²⁾	No Change	Last ⁽²⁾	Next ⁽³⁾	Prior ⁽³⁾
1R	No Change	Neutral ⁽¹⁾ (1N)	1F	2R	No Change
2R	No Change	Neutral ⁽¹⁾ (2N)	2F	3R	1R
3R	No Change	Neutral ⁽¹⁾ (3N)	3F	4R	2R
4R	No Change	Neutral ⁽¹⁾ (4N)	4F	No Change	3R

Show/hide table

^( 1 )	The speed and the direction that is shown in bold print is displayed on the gear indicator.
^( 2 )	A directional shift out of neutral will cause a speed shift to the last speed that was selected in either forward or reverse.
^( 3 )	Speed shifts are allowed when neutral is selected. The gear indicator will change the speed that is shown when neutral is selected and a speed shift is made. However, none of the solenoids are energized until forward or reverse is selected.

Transmission direction control switch (3) must be in the NEUTRAL position when the key is turned to the START position. If the transmission direction control switch is not in the NEUTRAL position, the start relay will not be activated. For additional information on the neutral start function, refer to "Neutral Start Function".

ReferenceFor information on the AVSpare Monitoring System, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Monitoring System (Power Train Functions)" for the machine that is being serviced.

ReferenceFor information on the transmission direction control switch and the upshift and downshift switches, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Switches" for the machine that is being serviced.

ReferenceFor information on the key start switch, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Switches" for the machine that is being serviced.

Automatic Shift Function

STIC Steering

Show/hide table




Illustration 4	g01026232
(1) Upshift switch (2) Downshift switch (3) Transmission direction control switch

Show/hide table




Illustration 5	g01026236
(4) Autoshift control switch (5) FOURTH position (6) THIRD position (7) SECOND position

Autoshift control switch (4) is used to select the top speed for the transmission when the transmission is in the automatic mode.

In order for the transmission to shift automatically, the four-position autoshift control switch (4) must be in one of the three AUTO positions: FOURTH position (5), THIRD position (6) or SECOND position (7) .

Shifting the transmission is accomplished automatically by the Power Train ECM. The Power Train ECM shifts the transmission according to the following parameters: engine speed and transmission output speed.

When the transmission is operating in automatic mode, the Power Train ECM will allow the transmission to select first gear. The Power Train ECM does not allow an upshift into a gear that is higher than the gear that is selected with autoshift control switch (4) .

When the machine is operating in automatic mode, downshift switch (2) can be used in order to downshift the transmission. The transmission will remain in the downshifted gear for two seconds after the switch is released. Then, automatic shifting will resume.

Transmission Neutralizer Function

Show/hide table




Illustration 6	g01026238
(1) Service brake and transmission neutralizer pedal (2) Transmission neutralizer switch

Transmission neutralizer switch (2) is located in the operator station and is activated by depressing service brake and transmission neutralizer pedal (1) .

When service brake and transmission neutralizer pedal (1) is depressed, the normally closed contacts of transmission neutralizer switch (2) open. The open contacts interrupt the power from the Power Train ECM. This causes the Power Train ECM to neutralize the transmission. The Power Train ECM de-energizes the solenoid valve for direction and leaves the solenoid valve for speed energized. The engine RPM will increase when the transmission is neutralized due to the no-load condition from the transmission. This allows full power for hydraulic system operation.

Note: When the transmission is neutralized, the gear indicator shows the speed that is selected and the direction will show neutral.

ReferenceFor information on the transmission neutralizer switch, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Switches" for the machine that is being serviced.

Parking Brake Function

The parking brake function prevents the operator from operating the machine while the parking brake is engaged.

When the parking brake switch is moved to the OFF position, the transmission will shift normally. When the parking brake switch is moved to the ON position, the transmission will not shift out of neutral to first speed forward or first speed reverse.

If the transmission is in first speed forward or in first speed reverse and the parking brake switch is moved to the ON position, the transmission will shift into neutral. All of the solenoid valves (transmission clutch) will be de-energized.

The transmission will remain engaged when the parking brake switch is moved to the ON position and the transmission is in the second, third or fourth speed in either the forward or reverse direction.

The Power Train ECM also sends the parking brake oil pressure switch status to the AVSpare Monitoring System via the AVS Data Link. The parking brake function activates a Warning Category 1 or a Warning Category 2-S on the AVSpare Monitoring System.

Warning Category 1 is activated whenever the parking brake is engaged. The parking brake indicator will flash.

While the parking brake is engaged, Warning Category 2-S will be activated. This will occur if the operator places the transmission direction control switch in the FORWARD position or the REVERSE position. The parking brake indicator will flash and the action lamp will flash. The action alarm will sound.

ReferenceFor information on the parking brake oil pressure switch, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Switches" for the machine that is being serviced.

Driving Through the Parking Brake

The Power Train ECM will allow the operator to drive through the parking brake. The machine should be moved only for a short distance. Driving through the parking brake causes accelerated wear to the friction components of the parking brake.

In order to drive through the parking brake, the operator must select first speed forward or first speed reverse. The operator must then move the transmission direction control switch to the NEUTRAL position. The operator must then move the transmission direction control switch to the previous direction that was selected.

Backup Alarm Function

The backup alarm function alerts surrounding personnel that the machine is backing up. The backup alarm is an output of the Power Train Electronic Control Module (ECM). The Power Train ECM activates the backup alarm when the transmission direction control switch is in the REVERSE position. The backup alarm receives a +battery signal from the Power Train ECM when the backup alarm is activated.

The backup alarm has two terminals for electrical connections. One terminal receives power from connector contact J2-37 of the Power Train ECM. The other contact provides frame ground to complete the circuit.

Ride Control Function

Show/hide table




Illustration 7	g00941484
(1) Ride control switch (2) Ride control indicator

Ride control is an optional function that is enabled by a programmable parameter via the AVSpare Electronic Technician (ET). Ride control can also be enabled by the calibration mode of the AVSpare Monitoring System. Ride control switch (1) has three positions, SERVICE position, OFF position and AUTO position.

When ride control switch (1) is moved and held in the SERVICE position, the ride control is activated at all times and the Power Train ECM continuously energizes the ride control solenoids. Ride control indicator (2) is on.

In the AUTO position, ride control is activated when the machine ground speed increases above approximately 5 km/h (3 mph). Ride control indicator (2) is on. In the AUTO position, ride control is deactivated when the machine ground speed is below approximately 5 km/h (3 mph). Ride control indicator (2) is off. The default speed can be changed with the configuration screen of the AVSpare Electronic Technician (ET).

The two ride control solenoids are outputs of the Power Train ECM. The ride control solenoids turn the ride control system on and off. When ride control is deactivated, both ride control solenoids are de-energized. When ride control is activated, both ride control solenoids are energized. Both of the ride control solenoids have a connector with two contacts. Both ride control solenoids receive power from the connector contact J1-18 of the Power Train ECM. Both of the ride control solenoids return power to frame ground.

ReferenceFor information on the Power Train ECM, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Electronic Control Module (Power Train)" for the machine that is being serviced.

Lockup Clutch Function

The lockup clutch function controls the torque converter direct drive electrically. When the Power Train ECM energizes the lockup clutch solenoid the lockup clutch in the torque converter mechanically connects the torque converter input shaft to the torque converter output shaft. This function efficiently connects the power train to the engine.

The Power Train ECM energizes the lockup clutch solenoid when all of the following conditions are met:

The torque converter lockup clutch switch is in the ON position.
The speed of the torque converter is greater than 1475 RPM.
The machine must be in any speed or direction other than first speed forward.
The machine has been in the present speed and direction for at least 0.8 seconds.
The service brake and transmission neutralizer pedal is fully released.
The lockup clutch solenoid was de-energized for four seconds.

The Power Train ECM de-energizes the lockup clutch solenoid when any one of the following conditions are met:

The torque converter lockup clutch switch is in the OFF position.
A shift is made.
The speed of the torque converter is less than 1325 RPM.
The speed of the torque converter is greater than 2500 RPM.
The service brake and transmission neutralizer pedal is depressed.
First speed forward is selected.

Dual Horsepower Function

The dual horsepower function allows the engine to operate at two horsepower settings. The Power Train Electronic Control Module (ECM) controls the dual horsepower function.

The Power Train ECM sends a signal via the AVS Data Link to the Engine ECM to select the high horsepower or the low horsepower setting. The Engine ECM selects the high horsepower or the low horsepower setting. Also the Power Train ECM receives a signal via the AVS Data Link from the Engine ECM that the high horsepower or the low horsepower setting has been selected. If the Power Train ECM does not receive the signal from the Engine ECM, the Power Train ECM will log a fault.

The Power Train ECM selects the high horsepower setting in second speed, third speed and fourth speed, in either the forward or the reverse direction.

The Power Train ECM will select the low horsepower setting in first speed, in either the forward or the reverse direction unless all of the following conditions are met:

The machine is in first speed in either the forward or the reverse direction
Engine speed is less than 1950 RPM.
Transmission output speed is less than 10 RPM.

If all the conditions are met the Power Train ECM will select the high horsepower setting.

Remote Control Function

The remote control system allows the operator to operate the machine by remote control. When the machine is operated by remote control the Power Train ECM operation changes.

When the machine is operated by remote control the Power Train ECM recognizes the input of the following switch:

Terminal 6 of the remote control switch connects to the J1-34 connector contact of the Power Train ECM.

ReferenceFor information on the remote control system refer to Remote Control System, Systems Operation, Testing and Adjusting for the machine that is being serviced.

Diagnostic Operation

The Power Train ECM detects faults that occur in most of the input circuits and the output circuits. A fault is detected when the signal at the contact of the Power Train ECM is outside a valid range. The Power Train ECM then records the fault. If the fault goes away, the fault information remains stored as a logged fault for future reference.

The diagnostics of the Power Train ECM are available to assist with the troubleshooting of detected faults. A service code is used to specify each fault. These service codes are shown in the display area of the AVSpare Monitoring System. Service codes consist of three identifiers: MID, CID and FMI.

Module Identifier (MID) - The MID is a three-digit code that is shown on the display area. The MID is shown for approximately one second before the service code that is shown in the same area. The Power Train ECM that has diagnosed the fault is logged by the MID. The following examples are of some MID.

Engine ECM ... 036

AVSpare Monitoring System ... 030

Power Train ECM ... 081

Note: The MID of the Power Train ECM is "081". Before troubleshooting the power train, make sure that "081" is the service code of the fault. The AVSpare Monitoring System also shows service codes of the faults that are not related to the power train system. MID 081 identifies the Power Train ECM as the source of the service code.

Component Identifier (CID) - The components that are faulty are noted by the CID. The following components are examples: start relay and reverse solenoid. The CID is a four digit code that is shown on the display area. The CID and the FMI are shown together after the MID has been displayed.

ReferenceFor a list of the CID codes for the Power Train ECM, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Diagnostic Codes List" for the machine that is being serviced.

Failure Mode Identifier (FMI) - The FMI tells the type of failure that has occurred. The following situations are examples: voltage above normal, current below normal and abnormal frequency. The FMI is a two digit code that is shown on the display area. The CID and the FMI are shown together after the MID has been displayed. A decimal point "." precedes the FMI.

ReferenceFor a list of the FMI codes for the Power Train ECM, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Diagnostic Code List" for the machine that is being serviced.

The Power Train ECM does not have a display area for displaying diagnostic information to service personnel. Diagnostic information concerning the power train system is sent on the AVS Data Link to the AVSpare Monitoring System. Service personnel must be familiar with the AVSpare Monitoring System in order to troubleshoot the power train system.

The service mode of the AVSpare Monitoring System allows service personnel to see the faults that were detected by the Power Train ECM. The service mode of the AVSpare Monitoring System allows service personnel to troubleshoot the faults that were detected by the Power Train ECM. While the AVSpare Monitoring System is in the service mode, the service code for any detected fault of the power train electronic control system is shown in the display area of the AVSpare Monitoring System.

When the service mode is first entered, all service codes for any detected faults scroll in the display area. For troubleshooting and clearing, the particular service code must be placed on hold. The display area continuously alternates between showing the MID, and then showing both the CID and the FMI of the particular service code for the fault that is on hold.

The AVSpare Monitoring System enters service mode when ground is removed from the service input and the clear input. The mode number 3 for service mode is shown in the display area of the AVSpare Monitoring System. To place a service code for a fault on hold, ground the service input. To clear a service code for a fault on hold, ground the clear input. The AVSpare Monitoring System exits service mode when ground is added to the service input and the clear input.

Note: The time that is needed to clear a fault and the time that is needed to set a fault can last less than 1 second up to 60 seconds.

ReferenceFor information on the AVS Data Link, refer to Systems Operation, Troubleshooting, Testing and Adjusting, "AVS Data Link" for the machine that is being serviced.