Chrysler DODGE D150 1993 Service Manual page 1490

EMISSION CONTROL SYSTEMS 25 - 13
For electrical tests of t h e EET and its circuitry, re­
fer to the appropriate Powertrain Diagnostic Proce­
dures service manual for use of the DRB II scan tool.
Refer to the Component Removal/Installation sec­
tion of this group for E E T replacement procedures.
OXYGEN (0
2
) SENSOR
For description, operation, diagnosis and removal/
installation procedures of the 0
2
sensor, refer to
Group 14, Fuel Systems.
AIR INLET—5.9L DIESEL ENGINE
The diesel engine air inlet system consists of the:
• Air filter housing
• Filter element
• Air filter housing-to-turbocharger inlet tube
• Air crossover tube
• Air intake heaters
Ambient air enters t h e air filter housing through
an opening at the bottom of the housing (Fig. 3). Air
in the housing is filtered by t h e air filter element
(Fig. 4) before it is drawn into the turbocharger.
Fig. 4 Air Filter Element—Diesel
The turbocharger increases the amount of air flow
to t h e engine. The turbocharger allows the engine to
use a higher air-to-fuel ratio. This results in im­
proved emissions.
Air flows from the turbocharger into the inter-
cooler (Fig. 5). Air leaves the intercooler, passes
through the air intake heaters and enters the intake
manifold.
TURBOCHARGER TURBOCHARGER
TO INTERCOOLER
INTERCOOLER
J9114-238
Fig. 5 Intercooler—Diesel
AIR INTAKE HEATER-DIESEL ENGINE
The air intake heater warms the intake air before
it enters the manifold. If intake manifold air temper­
ature is below 16°C (60°F) the powertrain control
module (PCM) will energize the heaters through the
air intake heater relays for start-up and initial
warm-up. Refer to Group 14, Fuel Systems for addi­
tional information.
The heater is located on top of the intake manifold,
below the air crossover tube (Fig. 6).
C A U T I O N : D o not energize the air intake heater re­
lays more than once per 15 minutes. If the relays
are cycled a n d the key is then turned off, wait 15
minutes before turning the key to the O N position.
The 15 minute period is to prevent damaging the
engine.
AIR INTAKE HEATER RELAYS-DIESEL
ENGINE
The powertrain control module (PCM) operates the
air intake heaters through the air intake heater re­
lays (Fig. 7). The relays are energized before crank­
ing if the charge air temperature sensor input to the
PCM indicates air temperature is 16°C (60°F) or be-