Dodge ram truck 3500 1996 Service Manual page 1358

14 - 124 FUEL SYSTEM
e n
1AGNOS9S
AND TESTING
( C o n t i n u e d )
FRONT OF ENGINE
AIR TEMPERATURE
SENSOR
SENSOR
ELECTRICAL
CONNECTOR
INTAKE
MANIFOLD
(UPPER HALF)
S H U
'
T
r x ) W N SOLENOID'
SOLENOID ELECTRICAL
. 9 4 1 4 . 9 0
CONNECTOR J V 4 1 4 V J
Fig. 24 Air Temperature Sensor LocaHon—-Diesei
TEMPERATURE RESISTANCE (OHMS)
C
F
mm
H A J C
-40 -40 291,490 381710
-20
- 4
85,850 108,390
-10
14
49,250 61,430
0 32 29,330 35,990
10 50 17,990 21,810
20 68 11,370 13,610
25 77 9,120 10,880
30 86 7,370 8,750
40 104 4,900 5,750
50 122 3,330 3,880
60 140 2,310 2,670
70 158 1,630 1,870
80 176 1,170 1,340
90 194 860 970
100 212 640 720
n o 230 480 540
120 248 370 410
J928D-4
Fig. 25 SENSOR RESISTANCE (OHMS)—INTAKE
MANIFOLD AIR TEMPERATURE SENSOR
(3) Test the resistance of the wire harness. Do this
between the powertrain control module (PCM) wire
harness connector terminal A-15 and the sensor con­
nector terminal. Also check between PCM terminal
A-4 (sensor return) to the sensor connector terminal.
Repair the wire harness as necessary i f the resis­
tance is greater than 1 ohm.
INTAKE MANIFOLD AIR HEATER TEST
The intake manifold air heater (Fig. 26) is con­
trolled by the powertrain control module (PCM)
through the intake manifold air heater relays (Fig.
27). This is done after a specified signal is sent to the
PCM from the intake manifold air temperature sen­
sor.
Two heating elements are located within the air
heater assembly. A separate heavy-duty cable is con­
nected to a separate terminal to supply power for
each element.
AIR
HEATER
ASSEMBLY
CAILE
NUTS (21
INTAKE MANIFOLD
BOLTS (5)
LOWER PART
OF INTAKE
MANIFOLD
CABLES (2)
CABLE
MOUNTING
STUDS (2)
DIPSTICK TUBE
BOLT
UPPER PART OF
INTAKE MANIFOLD
J9414-105
Fig. 26 Intake Manifold Air Heater
PfRBHEAT/POST-HEAT CYCLE
Refer to the Intake Manifold Air Heater Relays-—
PCM Output for preheat/post heat cycle information.
The PCM provides a ground path for the intake
manifold air heater relays. The ground path is pro­
vided i f intake manifold air temperature is 15°C
(59°F) when the ignition key is initially placed in the
ON position. When the ground is provided, the air
heater is energized to start the preheat cycle.
The preheat-cycle can be tested with a voltmeter or
test light. I f the intake manifold air temperature is
above 15°C (59°F), the wait-to-start warning * lamp
will not illuminate and the air heater will not be
energized.