MORTALIDAD ESPECÍFICA POR SUBGRUPO

The 24VDC electrical system components shown in Figure 3-1 are accessed by unlatching the passenger seat base lid and tilting the passenger seat forward. The electrical schematics in Section R should be used when troubleshooting problems with the following components.

TAIL LIGHT RESISTOR DIODE ASSEMBLIES

The tail light resistor diode assembly RD1, RD2 (2, Figure 3-1) is a circuit designed to vary the intensity of each of the stop/tail lamp bulbs.

With the tail lights on, a resistor in series with the lamp reduces voltage supplied to the lamp, thereby reducing the lamp intensity. When the service brakes are applied and the stop lights are activated, current flows from the stop light relay, bypassing the resistor and applies 24VDC to the lamp filament. The diodes direct current flow through the circuit.

RD1 controls the left lamp and RD2 controls the right lamp. No adjustments are available or necessary.

5 MINUTE IDLE TIMER COMPONENTS (Optional)

The optional 5 minute idle timer circuit automatically provides approximately 5 minutes engine idle time before actual engine shutdown occurs. This system allows the engine cooling system to circulate coolant to reduce and stabilize engine component tempera- tures, when engine power requirements are minimal, resulting in extended engine life. Circuit operation is described below.

NOTE: The engine may also be shut down immediately by turning the key switch off without actuating the idle timer or by using the ground level shutdown.

5 Minute Idle Timer

The 5 minute idle timer (6) circuit is activated when the operator presses the 5 minute idle timer engine shut- down switch mounted on the instrument panel. (This is a momentary switch that also latches the 5 minute idle timer contactor (7) in the energized position.) When the timer is energized, internal contacts close and energize the relay described below.

5 Minute Idle Relay

The relay (12) contacts close when the idle delay timer is energized. When the contacts are closed, the AID system indicator light circuit (12M) is grounded through the “5 minute idle timer” indicator lamp on the instrument panel, turning the lamp on.

5 Minute Idle Contactor

The contactor (7) energizes the idle timer and main- tains current flow to the engine “run” circuit if the operator turns the key switch off.

INCLINOMETER (Optional)

The inclinometer is used by the optional, on board load weighing system to determine whether the truck is on a level surface or tilted fore or aft. The information provided by the inclinometer is sent to the weighing system for use in calculating the payload. Refer to Section M for detailed information on the inclinomter and on board load weighing system.

BRAKE WARNING BUZZER

The brake warning buzzer (11) provides an audible alarm for the operator if a malfunction occurs in the hydraulic service brake system. Refer to Section J for additional operational details.

LUBRICATION SYSTEM TIMER (Optional)

The lubrication system timer is installed if the optional automatic lubrication system is installed on the truck. Lubrication frequency can be adjusted by removing the timer cover and selecting one of five different timing intervals available. System “on” time is automatically determined by the timer and is not adjustable.

Refer to Section M for additional automatic lubrication system details.

FIGURE 3-1. PASSENGER SEAT BASE COMPARTMENT 1. Seat Base

2. Tail Light Resistor/Diodes (RD1/RD2) 3. Terminal Board (TB13)

4. Terminal Board (TB12) 5. Terminal Board (TB11) 6. 5 Minute Idle Timer

7. 5 Minute Idle Contactor 8. Inclinometer

9. Hoist Control

10. Compartment Service Light 11. Brake Warning Buzzer (BWB)

12. 5 Minute Idle Relay

13. Auto-Lube Timer (Optional) 14. Connector (RP226)

15. Connector (RP231) 16. Connector (RP230) 17. AID Module

ALARM INDICATING DEVICE (AID) SYSTEM

The Alarm Indicating Device (17, Figure 3-1) used on HAULPAK® trucks is a device which is connected in the electrical accessories circuits to provide the opera- tor with a warning indication of a malfunction. This system consists of up to eight printed circuit cards, located under the passenger seat in the operators cab. The actual quantity of cards will depend on options installed on the truck.

The AID system enables the indicating lights to be flashing or constant. The AID also has the capability of operating an audible alarm along with the light. The eight printed circuit cards are:

• Diode Matrix (With Sound) Card (Slot 1) • Diode Matrix (Without Sound) Card (Slot 2) • Hot Switch Inverter Card (Slot 3)

• Hot Switch Inverter Card (Slot 4) (Not Used) • Temperature Card (Slot 5) (Optional) • Oil Level Card (Slot 6) (Optional) • Temperature and Latch Card (Slot 7) • Coolant Level and Flasher Card (Slot 8)

NOTE: Each card is identified with a number which corresponds with a mating number on the housing. If cards are removed, make sure card numbers corre- spond with housing numbers during installation (See Figure 3-2).

The following briefly describes each card and its func- tion. Refer to Section R for circuit components de- scribed below.

Prior to any welding on the truck, disconnect all AID system plug-in-cards.

Coolant Level/Flasher

The Coolant Level and Flasher Card contains two sepa- rate circuits. The flasher circuit at the top of the card has Q12 transistor biased to be saturated when no malfunction is present, resulting in there being 24 volt positive output on pin “H” of the card and on wire 12F. When a indicating circuit is activated, the ground side of the circuit connected to card pin “K” is grounded. Q12 will turn off initially and then after a delay, adjusted

by R20, will turn on and off to give the intermittent 24 volt output.

The other half of the circuitry on the Coolant Level and Flasher Card operates the Coolant Level Light. The Water Level Probe connected to terminal B11 grounds the 31L circuit when the coolant in the radiator is above the probe position. The coolant saturates the probe and electrically grounds the circuit. When the circuit is grounded, Q6 transistor is off, resulting in no indication. When the coolant level drops below the probe, 31L is no longer grounded and Q6 turns on to ground the flasher through D5, ground the Coolant Level Light through terminal D11, and ground the alarm horn through D6. The light and alarm horn will operate intermittently as their 24 volt supply is from circuit 12F, the flasher output.

NOTE: Some electronic engine controls monitor cool- ant level. If the engine controls monitor the circuit, a 2KΩ resistor is installed to replace the probe and

disable the AID system circuit.

FIGURE 3-2. AID SYSTEM 1. Diode Matrix With Sound 2. Diode Matrix Without Sound 3. Hot Switch Inverter

4. Hot Switch Inverter (Not Used) 5. Temperature & Latch

6. Coolant Level & Flasher

Temperature and Latch

The Temperature and Latch Card has two circuits to operate two different indicating lights. The temperature circuit is controlled by a coolant temperature sensor which decreases electrical resistance as its tempera- ture increases. It will have a resistance of approxi- mately 1000 ohms at 185oF (85oC) and 500 ohms at 250oF (122oC). Normal setting is 204oF (96oC). When the temperature is low and the resistance is high, Q1 is off no high temperature indication occurs. When the coolant temperature is excessive, resistance de- creases to a point where Q1 will turn on and ground the flasher through D8, the alarm horn through D12, and the High Temperature Light through terminal D8. R14 can adjust the temperature (resistance) at which the circuit is activated.

NOTE: Some electronic engine controls monitor cool- ant temperature. If the engine controls monitor the circuit, a 2KΩ resistor is installed to replace the tem-

perature sensor and disable the AID system circuit.

The Latch Circuit monitors the accumulator precharge pressure switches. When one of the pressure switches closes, Q5 will be turned off which supplies power to the gate of SCR Q7. With Q7 turned on, Q9 will supply the ground path to turn on the Low Accumulator Pre- charge Indicator Light and sound the alarm horn. The Indicator Light is connected to 12F and will flash off and on. The SCR will remain on until power is removed from the card by turning the key switch “Off”.

Hot Switch Inverter

The Hot Switch Inverter Card (Slot 3) is used to operate and test the service brake indicator light. In normal conditions Q4 transistor is off and the Indicator Light is off. When the stoplight switch is activated, 24 volts is sent to pin “E” of the Hot Switch Inverter Card. Tran- sistor Q4 is turned on by this voltage and, in turn, grounds the service brake Indicator Light. There is no alarm horn operation with this card.

A second circuit on this card is used to operate and test the Retard Speed Control indicator light. When RSC is turned Off, transistor Q7 is off and the indicator light is off. When RSC is turned on, 24 volts is sent to pin “J” of the card. This voltage turns on Q7, grounding the indicator light circuit.

Hot Switch Inverter Card (Slot 4)

This card is not used on trucks equipped with the Statex III control system.

Oil Level

The Oil Level Card (Optional) is used to turn on the Low Oil Level Indicator Light to warn the operator engine oil/hydraulic tank oil level is below acceptable levels. The oil float is connected to a variable resistor. As the oil level decreases, the resistance goes down causing Q3 to turn on, grounding the indicator light and alarm horn.

Temperature

The Temperature Card (Optional) is used to turn on the High Oil Temperature Indicator Light. The indicator light tells the operator hydraulic tank oil temperature has exceeded acceptable levels. Normal temperature setting is 250oF (121oC). As the temperature goes up the resistance in the probe decreases providing a ground path for the indicator light and alarm horn.

Diode Matrix (Without Sound)

The Diode Matrix Without Sound Card consists of a series of diodes capable of working with eight different indicator circuits. The indicator light can be a flashing light by connecting it to the 12F circuit or a steady light by connecting it to the 12M circuit. When an indicator circuit is not activated, there is no ground circuit for the bulb. When the Indicator detecting switch activates the circuit, it grounds the lamp and grounds the flasher circuit through the diodes. Any circuits connected to terminals C1 through C8 will operate in the same man- ner. The alarm horn is not activated by this card.

Diode Matrix (With Sound)

The Diode Matrix With Sound Card works very much like the other Diode Matrix Card, except that it contains extra diodes to activate the alarm horn in addition to the flasher. The circuits connected to terminals A1 through A8 operate in the same manner.

Lamp Test

All of the card circuits are connected to the Lamp Test Switch on the overhead display area. In normal opera- tion, these circuits are open and not functional. When the operator pushes the Lamp Test Switch, it activates all the indicator circuits by grounding them. This is used to verify that all lamps are functional.