Power Plant Instrumentation; Ammeter; Constant Voltage Regulator (Cvr) - Jeep 1979 CJ-5 Technical & Service Manual

1L-1
POWER PLANT
INSTRUMENTATION
SECTION INDEX
Circuits and Schematics
and Repair Simplification (DARS) Charts
General Information
Specifications—Cherokee
Page
1 L - 4 1
1 L - 7
1 1 - 1
1 1 4 2
Specifications—CJ
Specifications—Truck
Specifications—Wagoneer
Tools
Page
1 1 4 0
1L-42
1L-42
1L-44
G E N E R A L I N F O R M A T I O N
Constant Voltage Regulator (CVR) Replacement
Gauge Replacement
Instrument Cluster Replacement
Page
1L-7
1L-5
1L-4
Operation
Printed Circuit Replacement
Page
1 H
11-7
GENERAL
This chapter is divided into three sub-sections. The
first sub-section, General Information, contains verbal
descriptions of all instrumentation, operating prin-
ciples, test procedures and replacement procedures. The
second sub-section, Diagnosis and Repair Simplification
(DARS) Charts, contains pictorial guides for diagnosing
instrumentation malfunctions. The third sub-section,
Circuits and Schematics, contains specifications, cluster
illustrations, cluster schematics and separate schemat-
ics for each gauge circuit.
Power plant instrumentation includes all instrument
panel gauges used to monitor engine-related systems
i n c l u d e d in t h i s v o l u m e . R e f e r t o C h a p t e r
3C—Instrument Panels and Components for speedom-
eter, odometer, clock, illumination lamps, turn signal
indicators and high beam indicator. Instrumentation
covered in this chapter includes: ammeter, constant
voltage regulator (CVR), fuel gauge, oil pressure gauge,
tachometer, temperature gauge and voltmeter (fig. 1L-1
and 1L-2). These gauges are all electrically operated.
OPERATION
Ammeter
The ammeter is standard on Cherokee, Wagoneer and
Truck. It is not available on CJ models.
The ammeter is an instrument used to indicate cur-
rent flow into or out of the battery. Whenever electrical
loads in the vehicle are greater than the alternator can
supply, current flows from the battery, and the amme-
ter indicates discharge (-). Whenever alternator output
is greater than the electrical loads of the vehicle, the
excess current is available to charge the battery, and the
ammeter indicates charge (+). If the battery is fully
charged, the voltage regulator reduces alternator output
to meet only immediate vehicle electrical loads. When
this happens, the ammeter indicates zero.
The ammeter is connected between the battery and
the alternator in order to indicate current flow into and
out of the battery.
Constant Yoltage Regulator (CVR)
Several gauges in each vehicle are designed to operate
on low voltage. The CVR provides approximately 5 volts
for this purpose. Battery voltage is supplied to the CVR.
The CVR contains a small heating coil and thermostatic
points. With battery voltage applied to the CVR, the
points vibrate at a rate which supplies an average of 5
volts to the gauges. The CVR is built into the fuel gauge
on CJ models and into the temperature gauge on Chero-
kee, Wagoneer and Truck models. A circuit is provided
to carry CVR voltage to other gauges, as required.