S SERIES INSTRUMENTS
(BATTERY/CHARGING SYSTEM GAUGE)
The voltmeter or battery/charging system gauge (Figure
24) indicates the condition of battery and charging
system. This gauge will monitor a voltage range
between 10 and 16 volts. Color segments of this range
also indicate system condition as follows:
GREEN - A well-charged battery.
FIRE ORANGE - Either a too high or too low
Figure 24 - Voltmeter Circuit Diagram
With key switch "on" but before starting engine, the
voltmeter will show condition of battery. While starting
engine, indicator will temporarily descend to "Fire
Orange" segment but immediately return to "Green"
segment when engine is operating. With engine running
at operating speeds, the voltmeter indicator should
remain in the "Green" segment. This is charging
alternator is charging.
If indicator ascends to "Fire Orange" segment, alternator
voltage output is too high.
Constant reading in either high or low "Fire Orange"
segments of the voltmeter indicates a complete check of
appropriate alternator section of the Service Manual.
Operation of voltmeter can be checked by removing
terminals to an independent voltage source (12 V
battery). The voltmeter should indicate battery voltage 0
If voltmeter reads properly, voltmeter is OK and
problem is in vehicle wiring. Check continuity with test
If voltmeter does not read properly, replace voltmeter.
The exhaust pyrometer indicates the temperature of
exhaust gases leaving the engine.
The exhaust pyrometer system (Figure 25) consists of
the dash unit (gauge) mounted on the instrument panel,
the sender unit (thermocouple) mounted in the engines
exhaust outlet and the connecting wiring circuits.
Figure 25 - Pyrometer Tests
CTS-4140Y - Page 14