Dodge ram truck 3500 1996 Service Manual page 422

8E - 8 INSTRUMENT PANEL SYSTEMS B R
D I A G N O S I S A N D T E S T I N G ( C o n t i n u e d )
COOLANT TEMPERATURE GAUGE
The diagnosis found here addresses an inoperative
gauge condition. I f the problem being diagnosed is
related to gauge accuracy, be certain to confirm that
the problem is with the gauge and not with cooling
system performance. The actual engine coolant tem­
perature should be checked with a test gauge or ther­
mometer and compared to the gauge readings before
you proceed with gauge diagnosis. Refer to Group 7 -
Cooling System for more information. For circuit
descriptions and diagrams, refer to 8W-40 - Instru­
ment Cluster in Group 8W - Wiring Diagrams.
NOTE: Models equipped with the 8.0L V-10 engine
have the coolant temperature sending unit threaded
into the plastic water outlet. Therefore, an extra
spade terminal and connector near the side of the
coolant temperature sending unit is wired to pro­
vide a ground path for the sending unit case. Be
certain that there is continuity between the sending
unit case and ground on these models. If not OK,
repair this circuit to ground as required.
(1) Turn the ignition switch to the On position.
Disconnect the coolant temperature sending unit con­
nector (Fig. 1), (Fig. 2) or (Fig. 3). The gauge needle
should move to the low end of the gauge scale. I f OK,
go to Step 2. I f not OK, go to Step 3.
Fig. 1 Cooiant Temperature Sending Unit - V-6/V-8
Engine
(2) Install a jumper wire from the sending unit
connector to a good ground. The gauge needle should
move to the high end of the gauge scale. I f OK,
replace the faulty sending unit. I f not OK, remove
the jumper wire and go to Step 3.
(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the instrument cluster bezel and the cluster
assembly. Disconnect the left cluster connector.
Fig. 2 Coolant Temperature Sending Unit - V-10
Engine '
Fig. 3 Coolant Temperature Sending Unit - Diesel
Engine
(4) Probe the engine coolant temperature sending
unit circuit cavity of the left cluster connector. Check
for continuity to a good ground. There should be no
continuity. I f OK, go to Step 5. I f not OK, repair the
short circuit as required.
(5) Still probing the engine coolant temperature
sending unit circuit cavity of the left cluster connec­
tor, check for continuity to the sending unit connec­
tor. There should be continuity. I f OK, replace the
faulty gauge. I f not OK, repair the open circuit as
required.
FUEL GAUGE
The diagnosis found here addresses an inoperative
gauge condition. I f the problem being diagnosed is
related to gauge accuracy, be certain to confirm that
the problem is with the gauge or sending unit and
not with the fuel tank. Inspect the fuel tank for signs
of damage or distortion that could affect the sending
unit performance before you proceed with gauge