TOPIC 9. INSTRUMENT PANEL

TM 10-3930-644-14&P

TOPIC 9. INSTRUMENT PANEL

A. DESCRIPTION

may remain high for some time. If the ammeter

indicates a "discharge" condition when engine is

The truck instrumentation consists of the following

operated above idle speed, then the alternator is

components:

an oil pressure gauge, a coolant

not producing current, or there is a short in the

temperature gauge, fuel gauge, ammeter and engine

circuit.

hourmeter. All the instruments are mounted on the

instrument panel and are display oriented for ease of

2. Oil Pressure, Coolant Temperature and Fuel

use. Also mounted on the instrument panel are the

Gauges:

ignition switch, the electrical fuses and the manual choke

control.

The oil pressure, coolant temperature and fuel

level gauge all operate similarly in that one side

1. Ammeter:

of each gauge is tied to the ignition switch, while

the other side is connected to the respective

Connected directly into the battery circuit, this

sensing sender unit.

gauge indicates the status of the battery and the

direction of current flow. Pointer deflection to

The oil pressure sending unit mounts on the

the "charge" side of dial face indicates that the

engine oil gallery, the coolant temperature

battery is being charged by the alternator and

sending unit is located in the cylinder head

pointer deflection to the "discharge" side of dial

coolant outlet passage, and the fuel level

face Indicates that the battery is discharging.

sending unit is installed in the fuel tank

Normally, the "charge" rate will be high for a

assembly. The rheostat sensor in the sending

short time after starting engine, with pointer

unit allows more electrical current to flow

returning to slightly above zero after a few

through the respective gauge deflection coil as

moments of operation. However, if battery is run

the oil pressure increases, the engine coolant

down,

the

"charge"

rate

becomes warm, or as the fuel tank is being

filled.

Figure 9-1. Instrument Panel (Power Shift) (Typical)

M-146-1

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