Wait-To-Start Lamp; Water-In-Fuel Lamp - Dodge ram truck 3500 1996 Service Manual

BR INSTRUMENT PANEL SYSTEMS 8E - 7
DESCRIPTION AND OPERATION
(Continued)
the lamp bulb is switched by the Powertrain Control
Module (PCM). The lamp lights to indicate when the
driver should shift to the next highest gear for best
fuel economy. The PCM will turn the lamp off after 3
to 5 seconds if the upshift is not performed. The lamp
will remain off until the vehicle stops accelerating
and Is brought back to the range of lamp operation,
or until the transmission is shifted into another gear.
The indicator lamp is normally on when the Igni­
tion switch is in the On position, and is turned off
when the engine is started. The lamp will be turned
on and off during vehicle operation, according to the
engine speed and load conditions that are being mon­
itored by the PCM. Refer to Group 14 - Fuel System
for more Information on the PCM upshift indicator
lamp control output.
WAIT-TO-START LAMP
The wait-to-start lamp Is only used on diesel
engine models. The wait-to-start lamp bulb In the
message center is lighted by a ground signal from the
Powertrain Control Module (PCM), after the ignition
switch is turned to the On position. It gives the
driver an indication to wait until the intake manifold
air heater grid has had sufficient time to warm the
intake air for a good quality start. The intake mani­
fold air preheat cycle is controlled by an electronic
air heater control module. The lamp will be turned
off by the PCM when the heater control module cycle
is completed, or i f the driver turns the Ignition
switch to the Start position prior to the end of the
heater control module cycle. Refer to Group 14 - Fuel
Systems for more information.
WATER-IN-FUEL LAMP
The water-in-fuel lamp is only used on models with
the diesel engine option. The water-in-fuel lamp i n
the message center is turned on by the Powertrain
Control Module (PCM) for two seconds, when the
Ignition switch is first turned to the On position, as a
bulb check. The PCM will also turn on the lamp any
time there is excess water accumulated in the fuel
filter/water separator and the ignition switch Is In
the On position. A water-in-fuel sensor In the fuel fil­
ter/water separator signals the PCM' that excess
water has accumulated. The PCM will turn the lamp
off when the excess water has been' drained. Refer to
Group 14 - Fuel Systems for more information.
D I A G N O S I S A N D T E S T I N G
PRINTED CIRCUITS
GAUGE CLUSTER
If an Individual gauge or lamp is Inoperative, see
the diagnostic procedure under the heading for that
gauge or lamp. For circuit descriptions and diagrams,
refer to 8W-40 - Instrument Cluster in Group 8W -
Wiring Diagrams. I f more than one gauge or lamp is
inoperative, perform the following:
(1) Check the fuse in the fuseblock module. I f OK,
go to Step 2. I f not OK, replace the faulty fuse.
(2) Check for battery voltage at the fuse with the
ignition switch in the On position. I f OK, go to Step
3. I f not OK, repair the open circuit from the ignition
switch and/or refer to Group 8D - Ignition Systems
for testing of the ignition switch, as required.
(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 gauge cluster connectors.
(4) Connect the battery negative cable. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output circuit
cavity of the right cluster connector. I f OK, go to Step
5. I f not OK, repair the open circuit from the fuse as
required.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Probe the ground circuit cavities of both the left and
right cluster connectors. Check for continuity to a
good ground. There should be continuity. I f OK,
replace the faulty gauge cluster printed circuit. I f not
OK, repair the open circuit(s) to ground as required.
MESSAGE CENTER
If an individual lamp is inoperative, see the diag­
nostic procedure under the heading for that lamp.
The message center printed circuit is only serviced as
a part of the heater-A/C control unit. I f the printed
circuit is faulty, the entire control unit must be
replaced. For circuit descriptions and diagrams, refer
to 8W-46 - Message Center in Group 8W - Wiring
Diagrams. I f more than one lamp is inoperative, per­
form the following:
(1) Check the fuse in the fuseblock module. I f OK,
go to Step 2. I f not OK, replace the faulty fuse.
(2) Check for battery voltage at the fuse with the
ignition switch in the On position. I f OK, go to Step
3. I f not OK, repair the open circuit from the ignition
switch and/or refer to Group 8D - Ignition Systems
for testing of the ignition switch, as required.
(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the instrument cluster bezel and the mes­
sage center assembly. Disconnect the message center
connector.
(4) Connect the battery negative cable. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output circuit
cavity of the message center connector. I f OK, replace
the faulty heater-A/C control unit. I f not OK, repair
the open circuit from the fuse as required.