Chrysler RAM TRUCK 2500 1994 Service Manual page 407

8E - 10 INSTRUMENT PANEL AND GAUGES
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Fig. 10 Oil Pressure Lamp—Low Line Cluster
Fig. 11 Oil Pressure Gauge Terminals
tive, check battery feed from ignition switch through
fuse #12 and wiring to cavity #8 of cluster connector
B (black).
COOLANT TEMPERATURE SENDING UNIT
TEST
(1) Unplug connector from sending unit (Figs. 12,
13 or 14).
(2) Connect an ohmmeter between the sending
unit terminal and the engine block. There should be
a reading on the ohmmeter. Refer to Specifications
for the range. I f there is no reading, replace sending
unit. I f OK, continue with Coolant Temperature
Gauge Circuit Test.
COOLANT TEMIPEHATURE GAUGE CIRCUIT
TEST
Perform Coolant Temperature Sending Unit Test
before proceeding with circuit test.
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 .
(1) Unplug connector from sending unit (Figs. 12,
13 or 14) and turn ignition switch to ON. Gauge
should read at or below minimum. I f OK, continue to
next step. I f not OK, go to step (3).
(2) Using a jumper wire, ground sending unit con­
nector to engine. The gauge should read at or above
maximum. I f OK, check sending unit. I f not OK, turn
ignition switch to OFF, remove jumper wire and con­
tinue with next step.
(3) Pull instrument cluster from dash. Do not un­
plug cluster connectors. Refer to Instrument Cluster
Replacement for removal procedures.
(4) Check continuity between sending unit connec­
tor and temperature gauge input terminal (Figs. 15
or 16) on back of cluster. There should be continuity.
I f OK, continue with next step. I f not OK, repair
open circuit as required.
(5) Check continuity between temperature gauge
input terminal (Figs. 15 or 16) and ground. There
should be no continuity. I f OK, go to next step. I f not
OK, repair short circuit as required.
(6) With ignition switch i n ON position, check for
battery voltage across temperature gauge B+ termi­
nal and ground terminal (Figs. 15 or 16). I f OK, re­
place gauge. I f not OK, continue with next step.
(7) Unplug cluster connector B (black). With igni­
tion switch i n ON position, check for battery voltage
at cavity #8. I f OK, continue to next step. I f not OK,
repair circuit to fuse #12.
(8) Turn ignition switch to OFF and unplug cluster
connector A (white). Check for continuity to ground
at cavity #6. I f OK, replace cluster printed circuit
board. I f not OK, repair open circuit to ground.
VOLTMETER DIAGNOSIS
(1) Pull instrument cluster from dash. Do not un­
plug connectors. Refer to Instrument Cluster Re­
placement for removal procedures.
(2) With the ignition switch i n the ON position,
check for battery voltage across the B+ pin and the
ground pin (Fig. 17) on back of cluster. I f OK, replace
gauge. I f not OK, continue to next step.
(3) Unplug cluster connector A (white). With igni­
tion switch i n OFF position, check for continuity be­
tween connector cavity #6 and ground. There should
be continuity. I f OK, continue to next step. I f not OK,
repair open circuit to ground.
(4) Unplug cluster connector B (black). With igni­
tion switch i n ON position, check for battery voltage
at connector cavity #8. I f OK, replace cluster printed
circuit board. I f not OK, repair circuit to fuse #12.
SPEEDOMETER/ODOMETER DIAGNOSIS
When a problem occurs with speedometer/odometer
operation, before disassembling the cluster to check
the gauge, check for a defective vehicle speed sensor