SERVICE MANUAL FOR PA WINCH MODELS WITH ELECTRONIC CONTROLS Control System Operation and Troubleshooting Caterpillar


Control System Operation and Troubleshooting
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1.1. Basic Operation
2.1. Control Operation
3.1. Wiring Harness (D6T-Tier 4) (D6N-Series-Tier 4)
4.1. Brake On (Neutral) "Charging"
5.1. Brake On "Unloaded"
6.1. Brake-Off
7.1. REEL-IN
8.1. REEL-OUT
9.1. FREESPOOL
10.1. Troubleshooting
11.2. Electronic System Tests
12.2. Hydraulic System Tests

Basic Operation

The winch contains an independent, internal hydraulic system. The winch case serves as a reservoir and stores filtered oil for the internally mounted hydraulic pump. The pump is driven by a gear pressed onto the bevel pinion gear, and supplies oil as long as the tractor PTO shaft is turning. Oil from the pump is then routed through a pressure filter then directed to the control valve where a stand-by system pressure is maintained at 290-340 PSI (2000-2340 kPa)

The system oil pressure is routed through the control valve body to the solenoid actuated valve cartridges. When energized by the electronic control system, the solenoids direct oil to apply the Reel-In and Reel-Out clutches, release the spring-applied brake and shift the spring-engaged freespool mechanism. The electronic winch control system includes a sealed, solid-state joystick control lever and a sealed, solid-state control module, an electric solenoid operated control valve installed within the winch case, with a wiring harness connected between them.

The hydraulic control system is equipped with an accumulator. The spring-loaded accumulator stores a small amount of oil at system pressure to assist the application of the clutches and release of the brake under all operating conditions. The stored oil supply may also be used to release the spring-applied brake whenever the tractor engine or torque converter is installed. The accumulator-stored oil supply is continuously refilled by the pump and pressure maintenance system in the control valve whenever the PTO shaft is turning.

On tractors that supply PTO power through a torque converter, it is possible to cause the torque converter to stall if the tractor engine speed is too low. It is important that engine idle speeds be set to factory specifications to maintain proper operation.

The solid-state joystick control lever has no contact points to wear out or need adjustment, aside from the small push-button switch on the top of the lever. This button MUST be depressed to enable the electronic control system to perform any winch function. This feature prevents accidental or unwanted winch actuation.

The joystick produces a signal by a magnetically induced voltage as the control lever is moved near the sensing devices on the circuit board beneath the lever. The small, induced voltage is transmitted to the control module. The job of the control module is to receive 24V DC power from the tractor, filter this power supply to protect the electronics, then produce the correct combination of 24V DC signals to energize the appropriate solenoid cartridges in the control valve. The control valve is mounted inside the winch case behind the large access cover on the RH side. When energized by the control module, the solenoids send control oil pressure to perform the specific winch functions based on the position of the joystick lever. An additional terminal built into the winch end of the wiring harness allows for diagnostics and troubleshooting of electrical problems and components. A small red indicator light, installed next to the joystick, will illuminate to indicate that the hydraulic oil filter is beginning to bypass and should be serviced if the light remains on.

A small volume of oil is stored in the spring-type accumulator at control system pressure. This stand-by pressure ensures quick response to the operator's commands, regardless of engine speed or winch load. The stand-by pressure is maintained by the joint operation of a pressure switch and a main pressure control solenoid valve. The pressure switch will be closed and send current to the main pressure solenoid until stand-by pressure reaches 340 PSI (2345 kPa). When the cutout pressure is reached, the pressure switch de-energizes the solenoid valve. The stand-by pressure is contained in the control valve housing by a check valve, and slowly decreases to 290 PSI (2000 kPa), where it will close the pressure switch contacts and start the charging process again.

When the operator selects a winch function, the pressure switch is not used and the control module activates the main pressure solenoid. A relief valve limits the main system pressure to approximately 400 PSI (2760 kPa) during clutch and brake actuation.

The wiring harness provides the vital connection between the control module and the control valve. The connecting pins and sockets are numbered for identification and trouble-shooting. The pin and socket numbers are referenced in the following descriptions of winch functions.

Control Operation

A thorough understanding of the control system is needed before any trouble-shooting is begun. Please review the following descriptions of the control system to become familiar with the interaction of all the control circuit components.

All control diagnostic tests should be performed with an accurate 0-600 PSI (0-7000 kPa) hydraulic pressure gauge and an accurate digital or analog multi-meter. The main hydraulic test port is located on the RH side of the winch case next to the wiring harness connector. A female quick disconnect coupler is required for using the gauge.

Wiring Harness (D6T-Tier 4) (D6N-Series-Tier 4)

Brake On (Neutral) "Charging"


Control Valve

When "charging", 24 volts DC will be seen at the red and blue wire within the winch case. The blue wire will be de-energized when the circuit is "unloaded".

The pressure maintenance system operates continuously to maintain a stand-by supply of oil pressure for the control system. The pressure maintenance system consists of the following components:

Item 9- Check Valve
Item 10- Main Pressure Solenoid Valve
Item 11- Stand-By System Pressure Switch
Item 13- Accumulator Holding Cartridge
Item A- Accumulator

Oil from the pump passes through the filter and enters the valve housing. passing through the check valve (9) and holding cartridge (13) on its way to the accumulator (A). When charging first occurs, the pressure switch (11) contacts are closed producing a signal to energize the main pressure solenoid (10) to block the flow of oil to the lubrication circuit. At this time, all of the oil from the pump is directed to fill the accumulator and the pressure gallery in the control valve.

Brake On "Unloaded"


Control Valve

When the pressure at the pressure switch (11) reaches approximately 340 PSI (2345 kPa), the pressure switch opens and the main pressure solenoid (10) is de-energized. In the de-energized position, the main pressure solenoid valve (10) allows pump oil to flow through the lube circuit and return to the winch sump. The oil stored in the accumulator is trapped by the check valve (9) and the accumulator holding cartridge (13). This oil is available for clutch application and brake release.

When the pressure at the pressure switch (11) decreases to approximately 290 PSI (2000 kPa), either through system demand or internal system leakage. the pressure switch (11) contacts will close producing a signal to energize the main pressure solenoid valve (10). When energized, the main pressure solenoid valve (10) blocks the flow of oil to the lube circuit and the pump will refill the accumulator to approximately 340 PSI (2345 kPa).

In the "unloaded" mode, the main pressure solenoid is de-energized and the oil from the pump is flowing back to sump through the lube circuit. There is very little load on the winch pump at this time, thus reducing wear and heat.

Brake-Off


Control Valve

During BRAKE-OFF 24 volts DC will be seen at the red and blue wires within the winch case. As the joystick lever moves from the BRAKE-ON position into the full BRAKE-OFF position, the voltage at the brown wire increases proportionally from 0 to 24 volts DC.

To release the spring-applied brake requires the following components:

Item 2- Brake Control Solenoid
Item 6- Relief Valve
Item 10- Main Pressure Solenoid Valve
Item 13- Accumulator Holding Valve
Item A- Accumulator

In BRAKE-OFF, only the brake is released; the directional clutches are not affected. The brake circuit is unique in that the brake release oil pressure is proportional to the movement of the joystick lever into the BRAKE-OFF position. All other winch functions receive full control pressure, 400 PSI (2760 kPa) and full 24 volts DC to the solenoid valves. The main pressure solenoid valve (10) and the accumulator holding valve (13) receives 24 volts DC through the blue and purple wire within the winch case. The full flow of the pump is directed to the oil pressure gallery in the control valve. The pressure switch (11) is not used to control the maximum control system oil pressure when a winch function is selected. Instead of the pressure switch (11), the relief valve (6) limits the maximum pressure in the control circuit to approximately 400 PSI (2760 kPa).

After first pressing the enable switch, the movement of the joystick lever toward the BRAKE-OFF position will cause an increase in the voltage sent to the brake control solenoid (2) through the brown wire. As voltage increases, the valve opens further to send higher control pressure to release the spring-applied brake. When the joystick lever is placed in the full BRAKE-OFF position, full 24 volt DC current is sent to the control valve and full 400 PSI (2760 kPa) oil pressure is sent to fully release the brake.

When the joystick lever is released, the electrical signal to the solenoid is lost, the solenoid valves exhaust the control oil pressure to the winch sump, and the spring-applied brake reapplies to hold the load. The control valve returns to the BRAKE-ON mode and the pressure maintenance system begins slowly cycling to maintain a stand-by supply of control oil pressure.

REEL-IN


Control Valve

During REEL-IN 24 volts DC will be seen at the red, blue, purple, brown and white with black stripe wires within the winch case.

To apply the REEL-IN clutch and release the spring-applied brake requires the following components:

Item 1- C2 Clutch Solenoid
Item 2- Brake Control Solenoid
Item 6- Relief Valve
Item 10- Main Pressure Solenoid
Item 13- Accumulator Holding Valve
Item A- Accumulator

With the enable button pressed and the joystick lever moved to the REEL-IN position, a signal is sent to the control module to initiate a sequence of 24 volt DC signals to energize the proper solenoids of the control valve within the winch case. The main pressure solenoid (10) is energized to bring the control system oil pressure from stand-by pressure up to full pressure, 400 PSI (2760 kPa), by blocking the path to the lube circuit. The control system pressure is limited by the relief valve (6). The accumulator holding solenoid valve (13) is opened to allow the stored oil in the accumulator to enter the pressure gallery of the control valve. This action improves the response time and consistency of the REEL-IN clutch. The brake control solenoid (2) will be energized to begin the release of the brake as the C2 clutch control solenoid (1) is energized to begin the application of the REEL-IN clutch. The timing of the brake release and clutch application is electronically controlled to provide a shift with a minimal amount of load "fall-back" for good load control while minimizing clutch/brake disc scrubbing due to overlap.

When the joystick lever is released and returned to BRAKE-ON, the signal to the control module is cleared and the 24 volt DC signals to energize the solenoids are switched off. The clutch releases as the brake applies to hold the load. The pressure maintenance system will return to slowly cycling to maintain a stand-by supply of control oil pressure.

REEL-OUT


Control Valve

For REEL-OUT 24 volts DC will be present at the red, blue, purple, brown and white wires within the winch case.

To apply the REEL-OUT clutch and release the spring-applied brake requires the following components:

Item 2- Brake Control Solenoid
Item 3- C1 Clutch Control Solenoid
Item 6- Relief Valve
Item 10- Main Pressure Solenoid
Item 13- Accumulator Holding Valve
Item A- Accumulator

With the enable button pressed and the joystick lever moved to the REEL-OUT position, a signal is sent to the control module to initiate a sequence of 24 volt DC signals to energize the proper solenoids of the control valve within the winch case. The main pressure solenoid (10) is energized to bring the control system oil pressure from stand-by pressure up to full pressure, 400 PSI (2760 kPa), by blocking the path to the lube circuit. The control system pressure is limited by the relief valve (6). The accumulator holding valve (13) is opened to allow the stored oil in the accumulator to enter the pressure gallery of the control valve. This action improves the response time and consistency of the REEL-OUT clutch. The brake control solenoid (2) will be energized to begin the release of the brake as the C1 clutch control solenoid (1) is energized to begin the application of the REEL-OUT clutch. The timing of the brake release and clutch application is electronically controlled to provide a shift with a minimal amount of load "fall-back" for good load control while minimizing clutch/brake disc scrubbing due to overlap.

When the joystick lever is released and returned to BRAKE-ON, the signal to the control module is cleared and the 24 volt DC signals to energize the solenoids are switched off. The clutch releases as the brake applies to hold the load. The pressure maintenance system will return to slowly cycling to maintain a stand-by supply of control oil pressure.

FREESPOOL


Control Valve

For FREESPOOL 24 volts DC will be present at the red, blue, purple, brown and orange wires within the winch case. To operate the winch in FREESPOOL the following components are required:

Item 2- Brake Control Solenoid
Item 4- Freespool Cylinder Control Solenoid
Item 6- Relief Valve
Item 10- Main Pressure Solenoid
Item 13- Accumulator Holding Valve
Item A- Accumulator

With the enable button pressed and the joystick lever moved to the FREESPOOL position, a signal is sent to the control module to initiate a sequence of 24 volt DC signals to energize the proper solenoids of the control valve within the winch case.

The main pressure solenoid valve (10) is energized to bring the control system oil pressure from stand-by pressure up to full pressure, 400 PSI (2760 kPa), by blocking the path to the lube circuit. The control system pressure is limited by the relief valve (6). The accumulator holding solenoid valve (13) is opened to allow the stored oil in the accumulator to enter the pressure gallery of the control valve. The brake control solenoid (2) will be energized to release the brake. Once the brake is released and any load applied to the gear train has been relieved, the freespool cylinder solenoid (4) is energized. The solenoid actuates the cartridge to send oil to the freespool cylinder, which is installed in the LH side of the winch case. The cylinder is fitted with a shift yoke that moves a sliding collar gear into and out of engagement with the first reduction gear and second reduction pinion. The cylinder is spring-loaded to the "engaged" position keeping the cable drum load connected to the winch gear train and load holding brake. When disengaged, cable may be pulled from the cable drum by hand.

When the freespool operation is completed and the cable drum is stopped, the control lever may then be moved back into the BRAKE ON position. This will clear the signal from the joystick to the control module, which will call for the release of oil pressure from the freespool cylinder. The freespool cylinder springs will push the shift yoke and sliding collar gear back into engagement with the first reduction gear and second reduction pinion. This occurs first to ensure that the gear train is fully engaged before the brake control solenoid is de-energized to exhaust oil from the spring-applied brake. The pressure maintenance system of the control valve will return to slowly cycling to maintain a stand-by supply of control oil pressure, ready for the next command.

Troubleshooting

If the winch does not operate correctly, remove it from service immediately to avoid possible damage or injury from malfunctioning equipment.

Begin troubleshooting with a visual inspection of obvious faults, such as oil leaks, or loose or damaged parts. If the cause for the trouble is not readily apparent, check the operation of the winch in a secured test area.

Electronic System Tests

This section provides a quick reference guide to testing the electronic control components. An accurate multiple test meter is recommended, but a simple test light may be used on the solenoids. A small pocket screwdriver or similar light tool will easily sense the magnetism on energized solenoid coils. With the winch service access cover removed, place the small steel tool near the top of the solenoid coil. When energized, the tool will be drawn to the coil indicating the entire electrical side of the specific control circuit is operating.

The control valve solenoid coil resistance may be tested by unplugging the wires from the two spade connectors and attachment the test leads from an accurate Ohm meter to the solenoid coil spade operating.

At approximately 70°F (21°C), The main system flow solenoid coil (10) resistance is 41.7 Ohms. The resistance for all the other solenoid coils is 20.6 Ohms.

Test the wiring harness for continuity. Check from the spade connectors on the solenoids in the winch to the 24-pin connector on the front of the winch, then check the main harness from the 24-pin connector to the connector on the ECM. Refer to the wiring harness diagram on page 10 for wire and pin identification.

Hydraulic System Tests

In addition to the main pressure tap on the front of the winch case, there are individual circuit test ports on the brake housing cover/bearing carrier and on the clutch shaft bearing carrier cover. The brake cover has test ports for B-BRAKE-OFF pressure, C-Clutch pressure and F-Flush/lube oil pressure. The clutch shaft bearing carrier has a C-clutch pressure tap.

A quick indicator of general hydraulic system operation is accumulator rod extension. With the winch service access cover removed, you can view the extended length of the accumulator rod. Approximately 1.57 in (40 mm) is equal to 400 PSI (2760 kPa). The rod must be extended or the pressure is too low to fully apply a clutch and release the brake.

Information System:

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