Instrument Cluster Replacement; Tachometer Diagnosis; Temperature Gauge Diagnosis - Jeep 1979 CJ-5 Technical & Service Manual

1L-4 POWER PLANT INSTRUMENTATION
• Needle pulsates.
Refer to DARS chart 4 or 5 for a systematic method of
finding the causes of these problems.
Calibration Test
If an oil pressure gauge is suspected of indicating
pressure t h a t does not correspond with actual oil pres-
sure, perform a calibration test before performing elec-
trical diagnosis procedures in DARS chart 4 or 5.
(1) Remove sending unit from engine. Install T-fit-
ting in sending unit hole in engine. Install sending unit
to T-fitting.
(2) Connect direct-reading oil gauge to T-fitting.
(3) Start engine. Compare reading of vehicle gauge
with test gauge. Make observation at idle and at higher
engine speeds. If readings of both gauges are same
(within 10%), vehicle gauge is acceptable. If gauge is
outside specifications, perform gauge test as outlined in
DARS chart 4 or 5.
(4) After performing test, remove T-fitting, install
sending unit and check for leaks.
Tachometer Diagnosis
Test the accuracy of a tachometer by comparing with
a test tachometer of known accuracy. A special terminal
is provided on the coil connector for test tachometer
connection. Refer to Chapter 1G—-Ignition. Tachometers
are not adjustable. Replace if defective.
Temperature Gauge Diagnosis
Before performing temperature gauge diagnosis, be
sure the cooling system is performing properly. Over-
heating may be caused by low coolant level, restrictions,
loose or broken drive belt, defective water pump or in-
correct ignition timing. Undercooling may be caused by
a stuck thermostat. Be sure to consider these conditions
before suspecting an actual abnormal condition in the
indicating system. Abnormal conditions are all varia-
tions of four basic malfunctions:
• Needle does not move.
• Needle moves but indicates a temperature that does
not correspond with actual coolant temperature.
• Needle moves to top of scale and remains there.
• Needle pulsates.
Refer to DARS chart 6 for a systematic method of
finding the causes of these conditions. Charts 2 and 3
provide additional procedures needed only as directed in
chart 6.
Voltmeter
(1) Connect voltmeter of known accuracy across
battery terminals.
(2) Turn ignition switch On.
(3) Compare indication of test voltmeter with in-
dication of vehicle voltmeter. Replace voltmeter if read-
ings vary more than tolerance listed in Specifications.
INSTRUMENT CLUSTER REPLACEMENT
CJ Models
Removal
(1) Disconnect battery negative cable.
(2) Separate speedometer cable from speedometer
head.
(3) Remove four attaching nuts and pull cluster
from mounting studs.
(4) Note positions of all lamps. Note wire colors for
use during installation.
(5) Remove gauge wires and lamps.
Installation
(1) Install gauge wir.es and cluster lamps to cluster.
(2) Position cluster on mounting studs and install
attaching nuts.
(3) Connect speedometer cable.
(4) Connect battery negative cable.
(5) Reset clock, if equipped.
1
Cherokee-Wagoneer-Truck Models
Removal
(1) Disconnect battery negative cable.
(2) Remove cluster retaining screws.
(3) Disconnect speedometer cable at cluster.
(4) Disconnect cluster pin terminal plug by pulling
straight off.
(5) Disconnect four-terminal connector.
(6) Mark ammeter wires for identification during
installation. Disconnect ammeter wires.
(7) Disconnect fan wiring connector.
(8) Disconnect vacuum hoses from heater control.
N O T E : Tag each hose according to its numbered loca-
tion to ensure proper connection when installing cluster.
(9) Remove heater control panel lamps.
(10) Disconnect temperature control wire from lever.
(11) Remove cluster assembly.
Installation
(1) Connect harness connectors and identification
lamps to heater control.
(2) Connect temperature control wire to operating
lever.