ACTIVIDAD EMPRESARIAL Y SUELO INDUSTRIAL
4. Suelo industrial y territorio
The auxiliary control cabinet contains eight relay boards to provide control for many of the 24VDC circuits. Two types of boards are used. One type of board contains circuit breakers in addition to 24VDC relays and a PC board for special functions. The second type of board contains relays only.
All relays are interchangeable. The circuit breakers are also interchangeable as long as the circuit breaker capacity is the same.
Do not interchange or replace any circuit breaker with one of a different capacity than specified for the circuit. Serious damage or a fire may result if the wrong capacity breaker is used.
The relay boards are identified as follows:
Refer to Figure 3-1 for the location of each relay board. Refer to the Circuit Breakers chart at the end of this section for electrical circuit identification numbers.
Relay Boards RB1, RB3, RB4, RB5
Each relay board of this type is equipped with four green lights (9, Figure 3-6) and one red “breaker open” light (7). Each relay board has a fifth green (8) light that has a different function on each board.
Four green lights (9) are labeled K1, K2, K3, or K4.
These lights will be on only when that particular control circuit has been switched ON and the relay coil is being energized. The light will not turn on if the relay board does not receive the 24 volt signal to turn on a component.
If illuminated, red “breaker open” light (7) indicates that a circuit breaker on that relay board is in the OFF position. A light on the overhead display panel will also illuminate, informing the operator that a circuit breaker is in the OFF position. The red “breaker open” light will turn ON whenever there is a voltage difference across the two terminals of a circuit breaker.
If a control switch has been turned ON and a green (K) light is on, but that component is not operating, check the following on the relay board for that circuit:
If a circuit breaker light is on, press all the circuit breakers to make sure that they are all on. There is no visual indication as to which circuit breaker has been tripped.
Check the operation of the component. If it trips again, check the wiring or component for the cause of the overload.
The contacts inside the relay may not be closing, or the contacts may be open, preventing an electrical connection. Swap relays and check again. Replace defective relays. Relays may take one minute to trip and 30 seconds before they can be reset.
Check the wiring and all of the connections between the relay board and the component for an open circuit.
The component may be defective. Replace the component.
There is a poor ground at the component.
Repair the ground connection.
Relay Board Functions
RB1 Clearance/Turn Signal Lights RB3 Stop, Retard, Backup Lights RB4 Parking Brake, Horn, Body-Up,
Engine Cranking RB5 Headlights (standard)
RB6 Headlights (HID), Backup Horn, Auto Lube Solenoid & Timer, Ether Start, Engine Interlock, Bleeddown Power
RB7 Brake Lock, IM Warning, Timed Engine Shutdown
RB8 PLMIII Lights, Shutter Control, TCI RB9 Start Circuit, Brake Auto Apply,
Low Steering Pressure, Parking Brake OFF, Key Switch START
To replace a relay:
NOTE: The relays are labelled to identify the applicable circuits and components Also, refer to the Fuse Blocks charts at the end of this section.
1. Remove one screw (10, Figure 3-6) holding the crossbar in place and loosen the other screw.
2. Swing the crossbar away.
3. Gently wiggle and pull outward to remove relay (11).
4. Line up the tabs and install a new relay.
5. Place the crossbar in its original position and install screw (10). Tighten both screws.
FIGURE 3-6. TYPICAL RELAY BOARDS - RB1, RB3, RB4, RB5 1. Relay Board 2. Screw 3. Screw
4. Circuit Breaker 5. Circuit Panel Card 6. Screw
7. Breaker Open Light (RED) 8. Bleeddown Light (GREEN)
(Relay Board 4 Only) 9. K1, K2, K3, K4 Lights
(GREEN) 10. Screw 11. Relay
12. Circuit Harness Connector
D03040 1/08 24VDC Electrical System Components D3-11 To replace a circuit breaker:
NOTE: Always replace a circuit breaker with one of the same amperage capacity as the one being removed.
1. Activate the battery disconnect switches.
2. Unplug all wiring harnesses from the relay board. Remove the four relay board mounting screws. Remove the relay board from the truck.
3. Remove four hold down screws (2, Figure 3-6) (one in each corner) in the circuit breaker cover plate. Remove two screws (6) and card (5).
4. Remove the nuts on the wire terminal leads on the circuit breaker to be replaced. Remove mounting screws on circuit breaker to be replaced.
5. Lift out circuit breaker. Retain flat washers from wire terminals.
6. Install new circuit breaker of the same capacity rating as the one removed. Install one nut and two flat washers for each wire connection to the new circuit breaker.
7. Install cover plate and all screws removed during disassembly.
8. Carefully install card (5) with screws (6).
9. Install relay board in truck and connect all wiring harnesses.
To replace a circuit panel card:
NOTE: DO NOT remove the small screws that hold the cover plate to the circuit panel. Replace circuit panel as a complete assembly.
1. Place battery disconnect switches in the OFF position.
2. Remove the two mounting screws (6, Figure 3-6) and carefully remove the circuit panel card from the relay board.
3. Line up the new circuit panel in slots and with the socket on the relay board and install carefully.
4. Install two mounting screws (6).
Relay Board RB6, RB7, RB8, RB9
Relay boards 6, 7, 8 and 9 (Figure 3-7) do not contain circuit breakers or modular cards. Additional circuits may be added by utilizing a spare relay socket as described below:
The control circuit for the relays are the “+” and “-”
terminals:
• “+” terminal is for positive voltage.
• “-” terminal is for grounding of the control circuit.
• Either circuit can be switched “open” or “closed” to control the position of the relay.
The terminals of the switched circuit from the relay contacts are labeled as follows:
• NC - Normally Closed
• COM - Common
• NO - Normally Open
COM terminal is for the voltage source (protected by a circuit breaker) coming into the relay which will supply the electrical power for the component being controlled.
NC terminal is connected (through the relay) to the “COM” terminal when the relay is not energized (when the control circuit terminals “+” & “-” are not activated).
NO terminal is connected (through the relay) to the “COM” terminal when the relay is energized (by the control circuits “+” & “-”
being energized).
FIGURE 3-7. AUXILIARY RELAY BOARD - RB6, RB7, RB8, RB9
Relay Board Functions
The components and functions of each relay board are described below.
Relay Board 1 (RB1)
1 - Flasher Power Light (green): This light will be illuminated when the turn signals or hazard lights are activated.
1 light will be illuminated during right turn signal operation
2 light will be illuminated during left turn signal operation
3 light will be illuminated when clearance lights are activated.
4 light will be flashing when the turn signals or hazard lights are in operation.
NOTE: If circuit breakers CB13 and CB15 are in the OFF position, no warning will be noticed until the clearance light switch is turned ON.
1 - Flasher Module card
2 - 12.5 amp circuit breakers (CB13, CB15) 4 - Relays
Left Turn Light Relay (K1) Right Turn Light Relay (K2) Clearance Lights Relay (K3) Flasher Relay (K4)
Relay Board 3 (RB3)
1 - Light Module Display card
1 - Rev Light (green): This light is illuminated whenever the directional control lever is in the REVERSE position and the key switch is in the ON position.
4 - 12.5 amp circuit breakers (CB16, CB17, CB18, CB19) 4 - Relays
Manual Backup Lights Relay (K1) Stop Lights Relay (K2)
Relay Board 4 (RB4)
1 - Steering Pressure Bleeddown Timer Module card
1 - Bleeddown Light (green): This light is illuminated when the bleeddown solenoid is being energized. The bleeddown timer will energize the solenoid for 90 seconds after the key switch is turned OFF.
3 - 12.5 amp circuit breakers (CB20, CB21, CB22) 4 - Relays
Parking Brake Failure Relay (K1)
Engine Cranking Oil Pressure Interlock Relay (K2)
Horn Relay (K3) Body-Up Relay (K4)
Relay Board 5 (RB5)
1 - Light Display Module card
1 - Lights Control Light (green): This light is illuminated when 24 volts is being supplied to the battery terminal of the light switch.
5 - 12.5 amp circuit breakers
(CB23, CB24, CB25, CB26, CB27) 4 - Relays
Left Low Beam Relay (K1) Right Low Beam Relay (K2) Left High Beam Relay (K3) Right High Beam Relay (K4)
D03040 1/08 24VDC Electrical System Components D3-13 Relay Board 6 (RB6)
The following relays are installed on RB6:
Backup Horn Relay (K1) Engine Run/Ignition Relay (K2) Auto Lube Solenoid Relay (K3) Bleeddown Power Supply Relay (K4) Ether Start Relay (K5)
Spare Relay (K6)
HID Headlights Relay (K7) Auto Lube Timer Relay (K8)
Relay Board 7 (RB7)
The following relays are installed on RB7:
Brake Lock Limitation Relay (K1) Brake Lock Limitation Relay (K2) Brake Lock Limitation Relay (K3) Brake Lock Limitation Relay (K4) IM Warning Relay (K5)
Timed Engine Shutdown Light Relay (K6) Brake Lock Limitation Relay (K7)
Timed Engine Shutdown Relay (K8)
Relay Board 8 (RB8)
The following relays are installed on RB8:
70% Load Signal to PSC Relay (K1) Full Load Signal to PSC Relay (K2) A/C Shutter Control Relay (K3) PLMIII Lights Relay (K4) Shutter Control Relay (K5) PLMIII Red Lights Relay (K6) PLMIII Amber Lights Relay (K7) PLMIII Green Lights Relay (K8)
Relay Board 9 (RB9)
The following relays are installed on RB9:
Start Circuit Relay (K1)
Brake Auto Apply Power Relay (K2) Low Steering Pressure Power Relay (K3) Parking Brake OFF Relay (K4)
Key Switch Start Activation Relay (K5) Low Steering Pressure Ground Relay (K6) Spare Relay (K7)
Spare Relay (K8)
BODY-UP SWITCH
Body-up switch (3, Figure 3-8) is located inside the right frame rail near the front of the body. It must be adjusted to specifications to ensure that the proper electrical signal is obtained when the body is raised or lowered. The body-up switch is designed to prevent propulsion in REVERSE when the dump body is not resting on the frame rails. The switch also prevents forward propulsion with the body up unless the override button is depressed and held.
Operation
When the body is resting on the frame, actuator arm (4) causes the electrical contacts in the magnetically operated switch to close. When the body is raised, the arm moves away from the switch, opening the contacts. The electrical signal is sent to the control system and the body-up relay.
The switch must be properly adjusted at all times.
Improper adjustment or loose mounting bolts may cause false signals or damage to the switch assembly.
Adjustment
Before adjusting the body-up switch, inspect the body pads for wear and damage. Replace the body pads if required. The body must be resting on the frame in the normal body down position when adjustments are made.
1. Loosen capscrews (2, Figure 3-8) and adjust proximity switch bracket (3) to achieve an air gap (dimension “A”) of 12.7 to 15.9 mm (0.50 to 0.62 in.) between the sensing area (crosshatched area as marked on the switch) and actuator arm (4). Tighten the capscrews after the adjustment.
2. If necessary, loosen actuator arm mounting capscrews (5), and position arm until centered over sensing area of switch. Vertical set up dimension (“B”) should be 1.63 in. (41.5 mm).
Tighten the capscrews.
Service
Keep the sensing area clean and free of metallic dust and other debris that may damage or inhibit operation of the switch. If the switch is damaged or not functioning, the switch must be replaced.
1. Switch Mounting Bracket 2. Adjustment Capscrews 3. Proximity Switch 4. Actuator Arm
5. Adjustment Capscrews
D03040 1/08 24VDC Electrical System Components D3-15
HOIST LIMIT SWITCH
Hoist limit switch (5, Figure 3-9) is located inside the right frame rail above the rear suspension, near the body pivot pin. The hoist limit switch is designed to stop the hoist cylinders before they reach full extension, preventing possible damage to the dump body or hoist cylinders.
Operation
When the hoist cylinders approach maximum stroke and the body pivots on the pins, actuator arm (3) moves close enough to the magnetically-operated switch to close the electrical contacts. When the contacts close, an electrical signal is sent to the hoist-up limit solenoid valve, located in the hydraulic brake cabinet, to prevent further oil flow to the hoist cylinders.
The switch must be properly adjusted at all times.
Improper adjustment or loose mounting bolts may cause false signals or damage to the switch assembly.
Adjustment
1. Raise the body so that the hoist cylinders are within 152 mm (6 in.) of maximum travel.
2. Adjust the hoist limit switch to achieve an air gap (dimension “A”) of 12.70 to 14.30 mm (0.50 to 0.56 in.) between the sensing area and actuator arm (3). Tighten the capscrews.
Service
Keep the sensing area clean and free of metallic dust and other debris that may damage or inhibit operation of the switch. If the switch is damaged or not functioning, the switch must be replaced.
1. Body 2. Frame 3. Actuator Arm
4. Switch Mounting Plate
5. Hoist Limit Switch FIGURE 3-9. HOIST LIMIT SWITCH ADJUSTMENT