769D Off-Highway Truck Hydraulic System: Hoist System Enable - Check, Proportioning Solenoid (Hoist) - Test, & Control Valve (Hoist) - Test and Adjust

1.-Hoist System Enable - Check

Table 1

Tools Needed	Qty
Electronic Service Tool	1
JERD2124 Electronic Technician (ET) (Single User License)	1
JERD2129 ET Data Subscription	1
171-4400 Communication Adapter Gp	1

The trucks that are shipped with the 184-4671 Power Train Software and without the installed bodies will have the hoist enable parameter that is set to a value of 2. Value 2 is a test mode. Value 2 will prevent the hoist cylinders from being activated. Use the following procedure to check and change the value:

1. The engine should not be running.

2. The truck should not be moving.

3. TOS indicator needs to be zero in order to change the parameter.

(1) Communications port for ET



4. Install the Electronic Technician (ET) to the communications port (1) that is located in the cab.Note: If the screen for the Hoist Enable Status does not appear, disconnect ET and reconnect ET.

5. Use the drop-down menu in ET in order to obtain the screen for the configurable parameters.

6. If the value for Hoist Enable Status is 0 or the value is 2, change the value to 1.

7. Remove ET.

2.-Proportioning Solenoid (Hoist) - Test

Table 1

Tools Needed	Qty
132-7842 Adapter Cable As	2

Hoist control valve (1) Hoist proportioning solenoid for SNUB, FLOAT, and LOWER(2) Hoist proportioning solenoid for RAISE

1. Install a multimeter in series with hoist proportioning solenoid (1) .

2. Install a multimeter in series with hoist proportioning solenoid (2) .

3. Move the hoist control lever to the HOLD position and start the engine. Record the readings on both multimeters.

4. Move the hoist control lever to the RAISE position. Record the readings on both multimeters. Raise the dump body to the dump position.

5. Move the hoist control lever to the LOWER position. Record the readings on both multimeters.

6. As the dump body is lowering, release the hoist control lever. Record the readings on both multimeters. The recorded values are for the FLOAT position.

7. When the dump body contacts the frame, record the readings on both multimeters. The recorded values are for the SNUB position.

8. Disconnect both of the multimeters.

9. Compare the recorded values with the values in Table 2.

Table 2

Hoist Control Lever	Solenoid (1)	Solenoid (2)
HOLD	0 amp	0 amp
RAISE	0 amp	1.9 amp
LOWER	1.9 amp	0 amp
FLOAT	1.69 amp	0 amp
SNUB	0.81 amp	0 amp

Problem: The values do not match the table.

Probable Cause

• The hoist control position sensor is not sending the correct signal to the Power Train Electronic Control Module (Power Train ECM). Use the Caterpillar Monitoring System to view the input signal to the Power Train ECM.
• The Power Train ECM is not sending the correct signal to the hoist proportioning solenoids. Use the Caterpillar Monitoring System to view the output signal from the Power Train ECM.
• The hoist proportioning solenoid or the wiring from the Power Train ECM has failed.

Note: The Electronic Technician (ET) can also be used to view the input to the Power Train ECM. The Electronic Technician (ET) can also be used to view the output from the Power Train ECM.

3.-Control Valve (Hoist) - Test and Adjust

Table 1

Tools Needed	Qty
6V-7830 Pressure Gauge	1
Electronic Service Tool	1
JERD2124 Electronic Technician (ET) (Single User License)	1
JERD2129 ET Data Subscription	1
171-4400 Communication Adapter Gp	1

The command for the hoist control valve is adjustable. The adjustment range is -5 to +5 with zero as a default. A positive adjustment will increase the command to the hoist control valve. A positive adjustment causes the body to come down faster. A negative adjustment will decrease the command to the hoist control valve. A negative adjustment causes the body to lower more slowly.
Note: The adjustment to the hoist control valve may not be available on some early ECM systems. On some early machines, the adjustment range may be from zero to 10 with 5 as the default on these early ECM systems.

(1) Pressure tap

1. Connect a 6V-7830 Pressure Gauge on the pressure tap (1) of the gear pump for the hoist and rear brake.

(2) Communications port for ET



2. Install the Electronic Technician (ET) to the communications port (2) that is located in the cab.

3. Use the drop-down menu in ET in order to obtain the screen for "Transmission ECM configuration".

4. With the body in the down position, place the hoist lever in the HOLD position.

5. Use the ET in order to change the setting for the hoist control valve to the desired setting between -5 to +5. The procedure begins at zero. Change the setting of the hoist control valve one increment at a time. A positive change or the negative change can be made to the setting.

6. Raise the body to the full up position.

7. Place the hoist lever in the FLOAT position. Check the body down snub function as the body lowers to the frame.

8. If further adjustment is required repeat Steps 3 through Step 7.

9. In order to check pressure in the outlet port of the hoist, the hoist status must be in the SNUB mode on the "Transmission ECM configuration" status screen in ET.

10. Run the engine at high idle with the hoist control in the FLOAT position.

Note: If the pressure is greater than 1725 kPa (250 psi), the adjustment for the command to the hoist control valve is too high. A setting to the control that is too high causes excessive oil to be diverted to the hoist control valve. Diverting too much oil will cause overheating of the brake oil when the body is in the FLOAT position. Repeat steps 3 through step 7 and lower the adjustment for the hoist control valve.

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769D Off-Highway Truck Hydraulic System: Hoist System Enable - Check, Proportioning Solenoid (Hoist) - Test, & Control Valve (Hoist) - Test and Adjust 2013-01-07T15:36:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown