Chrysler RAM TRUCK 2500 1994 Service Manual page 403

8E - 6 INSTRUMENT PANEL AND GAUGES
CLUSTER AND
G A U G E
TEST PROCEDURES
INDE1
page
Coolant Temperature Gauge Diagnosis 9
Fuel Gauge Diagnosis , 6
Instrument Cluster Connectors 17
Instrument Cluster Printed Circuit Board—High
Line . 17
Instrument Cluster Printed Circuit Board—Low
Line . . . . . . . . 18
Low Fuel Warning Diagnosis 7
page
Oil Pressure Gauge Diagnosis
7
Specifications 19
Speedometer/Odometer Diagnosis 10
Tachometer Diagnosis 12
Vehicle Speed Sensor 12
Voltmeter Diagnosis 10
Warning Lamp System Tests 13
CAUTION: Disconnect battery negative cable(s), in
engine compartment, before servicing instrument
panel. When power is required for test purposes,
connect battery cable (for test only).
D i s c o n n e c t b a t t e r y
negative cable(s) after test
and before continuing service procedures.
FUEL GAUGE DIAGNOSIS
I f all gauges and warning lamps are inoperative,
check battery feed from ignition switch to fuse #12,
then check wiring from fuse to cavity #8 of cluster
connector B (black).
FUEL GAUGE
C I R C U I T T E S T
(1) Unplug connector from fuel tank sending unit.
Check sending unit ground cavity of connector (Fig.
1) for continuity to ground. I f OK, go to next step. I f
not OK, repair circuit to ground.
FUEL PUMP SUPPLY
INPUT T O G A U G E
SENDING UNIT G R O U N D
FUEL PUMP G R O U N D
J928E-49
Fig. 1 Fuel Tank Sending Unit Connector
(2) With sending unit connector unplugged, turn
ignition switch to ON. Gauge should read EMPTY. I f
OK, continue to next step. I f not OK, go to step (4).
CAUTION: When connecting an input terminal to
ground, DO NOT leave the connection grounded for
more than a few s e c o n d s .
(3) With ignition switch ON, connect a jumper wire
between input to gauge cavity and sending unit
ground cavity of sending unit connector (Fig. 1).
Gauge should read FULL. I f OK, see Fuel Tank
Sending Unit Test. I f not OK, turn ignition switch
OFF and continue to next step.
(4) Pull instrument cluster from dash. Do not un­
plug cluster connectors. Refer to Instrument Cluster
Replacement for removal procedures.
(5) Check for continuity i n wire between un­
plugged fuel tank sending unit connector input to
gauge cavity (Fig. 1) and fuel gauge input terminal
(Figs. 3 or 4). I f OK, continue to next step. I f not OK,
repair open circuit as required.
(6) Unplug instrument cluster connector B (black).
Check for continuity between unplugged fuel tank
sending unit connector input to gauge cavity (Fig. 1)
and a good ground. There should be no continuity. I f
OK, reinstall cluster connector B and continue to
next step. I f not OK, repair short circuit as required.
(7) With ignition switch i n ON position, check for
battery voltage across fuel gauge B+ terminal and
ground terminal (Figs. 3 or 4). I f OK, replace gauge.
I f not OK, continue to next step.
(8) With ignition switch i n ON position, check for
battery voltage at cavity #8 of cluster connector B
(black). With ignition switch i n OFF position, check
for continuity to ground at cavity #9 of cluster con­
nector B (black). I f both OK, replace cluster printed
circuit board. I f not OK, repair ground or feed circuit
as required.
F U E L T A N K SENDING UNIT TEST
(1) I f the fuel gauge passes tests i n steps (1)
through (3) above, check fuel tank sending unit as
follows:
(a) Carefully remove fuel tank sending unit from
tank. Refer to Group 14 - Fuel System.
(b) Check for correct resistance measurements as
shown i n Specifications. I f not OK, replace sending
unit (Fig. 2).
(2) I f fuel gauge and sending unit are operating,
but sending unit accuracy is suspect, check the fol­
lowing:
(a) Fuel tank bottom deformed causing improper
positioning of sending unit pick up tube or float