Page 2177 of 2255

(3) Tighten the accumulator retaining band screw
to 4.5 N´m (40 in. lbs.).
(4) Remove the tape or plugs from the refrigerant
line fittings on the suction line and the accumulator
outlet. Connect the suction line refrigerant line cou-
pler to the accumulator outlet. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - A/C LINE COUPLERS)
(5) Reinstall the a/c low pressure switch on the
accumulator. (Refer to 24 - HEATING & AIR CON-
DITIONING/CONTROLS/A/C LOW PRESSURE
SWITCH - INSTALLATION)
(6) Connect the battery negative cable.
(7) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(8) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
NOTE: If the accumulator is replaced, add 60 milli-
liters (2 fluid ounces) of refrigerant oil to the refrig-
erant system. Use only refrigerant oil of the type
recommended for the compressor in the vehicle.
HEATER CORE
DESCRIPTION
The heater core is located in the HVAC housing,
under the instrument panel. It is a heat exchanger
made of rows of tubes and fins.
The heater core is not repairable and if damaged it
must be replaced.
OPERATION
Engine coolant is circulated through heater hoses
to the heater core at all times. As the coolant flows
through the heater core, heat removed from the
engine is transferred to the heater core fins and
tubes. Air directed through the heater core picks up
the heat from the heater core fins. The blend door
allows control of the heater output air temperature
by controlling how much of the air flowing through
the HVAC housing is directed through the heater
core. The blower motor speed controls the volume of
air flowing through the HVAC housing.
The heater core cannot be repaired and, if faulty or
damaged, it must be replaced.
REMOVAL
(1) Remove the HVAC housing from the vehicle.
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - REMOVAL)(2) Remove the screws and retainers that secure
the heater core to the HVAC housing.
(3) Lift the heater core straight up and out of the
heater-A/C housing (Fig. 14).
INSTALLATION
(1) Lower the heater core into the HVAC housing.
(2) Position the retainers over the heater core
tubes. Install and tighten the screws that secure the
heater core and retainers to the HVAC housing.
Tighten the screws to 2.2 N´m (20 in. lbs.).
(3) Reinstall the HVAC housing in the vehicle.
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - INSTALLA-
TION)
REFRIGERANT
DESCRIPTION
The refrigerant used in this air conditioning sys-
tem is a HydroFluoroCarbon (HFC), type R-134a.
Unlike R-12, which is a ChloroFluoroCarbon (CFC),
R-134a refrigerant does not contain ozone-depleting
chlorine. R-134a refrigerant is a non-toxic, non-flam-
mable, clear, and colorless liquefied gas.
Even though R-134a does not contain chlorine, it
must be reclaimed and recycled just like CFC-type
refrigerants. This is because R-134a is a greenhouse
gas and can contribute to global warming.
Fig. 14 HEATER CORE REMOVE/INSTALL
1 - HEATER CORE LINES
2 - HEATER CORE
24 - 56 PLUMBINGBR/BE
ACCUMULATOR (Continued)
Page 2178 of 2255

OPERATION
R-134a refrigerant is not compatible with R-12
refrigerant in an air conditioning system. Even a
small amount of R-12 added to an R-134a refrigerant
system will cause compressor failure, refrigerant oil
sludge or poor air conditioning system performance.
In addition, the PolyAlkylene Glycol (PAG) synthetic
refrigerant oils used in an R-134a refrigerant system
are not compatible with the mineral-based refriger-
ant oils used in an R-12 refrigerant system.
R-134a refrigerant system service ports, service
tool couplers and refrigerant dispensing bottles have
all been designed with unique fittings to ensure that
an R-134a system is not accidentally contaminated
with the wrong refrigerant (R-12). There are also
labels posted in the engine compartment of the vehi-
cle and on the compressor identifying to service tech-
nicians that the air conditioning system is equipped
with R-134a.
REFRIGERANT OIL
DESCRIPTION
The refrigerant oil used in R-134a refrigerant sys-
tems is a synthetic-based, PolyAlkylene Glycol (PAG),
wax-free lubricant. Mineral-based R-12 refrigerant
oils are not compatible with PAG oils, and should
never be introduced to an R-134a refrigerant system.
There are different PAG oils available, and each
contains a different additive package. The SD7H15
compressor used in this vehicle is designed to use an
SP-20 PAG refrigerant oil. Use only refrigerant oil of
this same type to service the refrigerant system.
OPERATION
After performing any refrigerant recovery or recy-
cling operation, always replenish the refrigerant sys-
tem with the same amount of the recommended
refrigerant oil as was removed. Too little refrigerant
oil can cause compressor damage, and too much can
reduce air conditioning system performance.
PAG refrigerant oil is much more hygroscopic than
mineral oil, and will absorb any moisture it comes
into contact with, even moisture in the air. The PAG
oil container should always be kept tightly capped
until it is ready to be used. After use, recap the oil
container immediately to prevent moisture contami-
nation.
STANDARD PROCEDURE - REFRIGERANT OIL
LEVEL
When an air conditioning system is assembled at
the factory, all components except the compressor are
refrigerant oil free. After the refrigerant system has
been charged and operated, the refrigerant oil in the
compressor is dispersed throughout the refrigerant
system. The accumulator, evaporator, condenser, and
compressor will each retain a significant amount of
the needed refrigerant oil.
It is important to have the correct amount of oil in
the refrigerant system. This ensures proper lubrica-
tion of the compressor. Too little oil will result in
damage to the compressor. Too much oil will reduce
the cooling capacity of the air conditioning system.
It will not be necessary to check the oil level in the
compressor or to add oil, unless there has been an oil
loss. An oil loss may occur due to a rupture or leak
from a refrigerant line, a connector fitting, a compo-
nent, or a component seal. If a leak occurs, add 30
milliliters (1 fluid ounce) of refrigerant oil to the
refrigerant system after the repair has been made.
Refrigerant oil loss will be evident at the leak point
by the presence of a wet, shiny surface around the
leak.
Refrigerant oil must be added when a accumulator,
evaporator coil, or condenser are replaced. See the
Refrigerant Oil Capacities chart. When a compressor
is replaced, the refrigerant oil must be drained from
the old compressor and measured. Drain all of the
refrigerant oil from the new compressor, then fill the
new compressor with the same amount of refrigerant
oil that was drained out of the old compressor.
Refrigerant Oil Capacities
Component ml fl oz
A/C System 210 6.2
Accumulator 60 2
Condenser 30 1
Evaporator 60 2
Compressordrain and measure
the oil from the old
compressor - see
text.
BR/BEPLUMBING 24 - 57
REFRIGERANT (Continued)
Page 2179 of 2255
Page 2180 of 2255

EMISSIONS CONTROL
TABLE OF CONTENTS
page page
EMISSIONS CONTROL
DESCRIPTION
DESCRIPTION - DIESEL.................1
DESCRIPTION - STATE DISPLAY TEST
MODE...............................1
DESCRIPTION - CIRCUIT ACTUATION TEST
MODE...............................2
DESCRIPTION - DIAGNOSTIC TROUBLE
CODES..............................2
DESCRIPTION - TASK MANAGER.........17
DESCRIPTION - MONITORED SYSTEMS . . . 17
DESCRIPTION - TRIP DEFINITION........19
DESCRIPTION - COMPONENT MONITORS -
GAS ENGINES.......................19DESCRIPTION - COMPONENT MONITORS -
DIESEL ENGINES.....................20
OPERATION
OPERATION - GAS ENGINES............20
OPERATION - DIESEL..................20
OPERATION - TASK MANAGER..........21
OPERATION - NON-MONITORED
CIRCUITS - GAS ENGINES..............24
OPERATION - NON-MONITORED
CIRCUITS - DIESEL....................24
AIR INJECTION.........................26
EVAPORATIVE EMISSIONS................32
EMISSIONS CONTROL
DESCRIPTION
DESCRIPTION - DIESEL
Two different modules are used for powertrain con-
trol with the diesel engine. The Powertrain Control
Module (PCM) is used primarily for charging system,
transmission, A/C compressor clutch operation and
speed control functions. The Engine Control Module
(ECM) is used to control thefuel and emissions
systems.The PCM is located in the right/rear of
engine compartment (Fig. 1). The ECM is bolted to
the left side of the engine cylinder block (Fig. 2).
DESCRIPTION - STATE DISPLAY TEST MODE
The switch inputs to the Powertrain Control Mod-
ule (PCM) have two recognized states; HIGH and
LOW. For this reason, the PCM cannot recognize the
difference between a selected switch position versus
an open circuit, a short circuit, or a defective switch.
If the State Display screen shows the change from
HIGH to LOW or LOW to HIGH, assume the entire
switch circuit to the PCM functions properly. Connectthe DRB scan tool to the data link connector and
access the state display screen. Then access either
State Display Inputs and Outputs or State Display
Sensors.
Fig. 1 Powertrain Control Module (PCM) Location
1 - PCM MOUNTING BOLTS (3)
2 - POWERTRAIN CONTROL MODULE (PCM)
3 - (3) 32±WAY CONNECTORS
BR/BEEMISSIONS CONTROL 25 - 1
Page 2181 of 2255

DESCRIPTION - CIRCUIT ACTUATION TEST
MODE
The Circuit Actuation Test Mode checks for proper
operation of output circuits or devices the Powertrain
Control Module (PCM) may not internally recognize.
The PCM attempts to activate these outputs and
allow an observer to verify proper operation. Most of
the tests provide an audible or visual indication of
device operation (click of relay contacts, fuel spray,
etc.). Except for intermittent conditions, if a device
functions properly during testing, assume the device,its associated wiring, and driver circuit work cor-
rectly. Connect the DRB scan tool to the data link
connector and access the Actuators screen.
DESCRIPTION - DIAGNOSTIC TROUBLE CODES
A Diagnostic Trouble Code (DTC) indicates the
PCM has recognized an abnormal condition in the
system.
Remember that DTC's are the results of a sys-
tem or circuit failure, but do not directly iden-
tify the failed component or components.
NOTE: For a list of DTC's, refer to the charts in this
section.
BULB CHECK
Each time the ignition key is turned to the ON
position, the malfunction indicator (check engine)
lamp on the instrument panel should illuminate for
approximately 2 seconds then go out. This is done for
a bulb check.
OBTAINING DTC'S USING DRB SCAN TOOL
(1) Connect the DRB scan tool to the data link
(diagnostic) connector. This connector is located in
the passenger compartment; at the lower edge of
instrument panel; near the steering column.
(2) Turn the ignition switch on and access the
ªRead Faultº screen.
(3) Record all the DTC's and ªfreeze frameº infor-
mation shown on the DRB scan tool.
(4) To erase DTC's, use the ªErase Trouble Codeº
data screen on the DRB scan tool.Do not erase any
DTC's until problems have been investigated
and repairs have been performed.
Fig. 2 Engine Control Module (ECM) Location
1 - ENGINE CONTROL MODULE (ECM)
2 - HEX HEADED BOLT
3 - FUEL TRANSFER PUMP
4 - MOUNTING BOLTS (3)
5 - 50±WAY CONNECTOR
25 - 2 EMISSIONS CONTROLBR/BE
EMISSIONS CONTROL (Continued)
Page 2182 of 2255

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0030 (M) 1/1 O2 Sensor Heater Circuit
MalfunctionProblem detected in oxygen sensor heater relay circuit.
P0031 (M) 1/1 O2 Sensor Heater Circuit Low Problem detected in oxygen sensor heater relay circuit.
P0032 (M) 1/1 O2 Sensor Heater Circuit High Problem detected in oxygen sensor heater relay circuit.
P0036 (M) 1/2 O2 Sensor Heater Circuit
MalfunctionProblem detected in oxygen sensor heater relay circuit.
P0037 (M) 1/2 O2 Sensor Heater Circuit Low Problem detected in oxygen sensor heater relay circuit.
P0038 (M) 1/2 O2 Sensor Heater Circuit High Problem detected in oxygen sensor heater relay circuit.
P0043 (M) 1/3 O2 Sensor Heater Circuit Low Problem detected in oxygen sensor heater relay circuit.
P0044 (M) 1/3 O2 Sensor Heater Circuit High Problem detected in oxygen sensor heater relay circuit.
P0051 (M) 2/1 O2 Sensor Heater Circuit Low Problem detected in oxygen sensor heater relay circuit.
P0052 (M) 2/1 O2 Sensor Heater Circuit High Problem detected in oxygen sensor heater relay circuit.
P0057 (M) 2/2 O2 Sensor Heater Circuit Low Problem detected in oxygen sensor heater relay circuit.
P0058 (M) 2/2 O2 Sensor Heater Circuit High Problem detected in oxygen sensor heater relay circuit.
P0071 (M) Amb/Bat Temp Sensor Performance
P0106 Barometric Pressure Out of Range MAP sensor input voltage out of an acceptable range
detected during reading of barometric pressure at key-on.
P0107 (M) Map Sensor Voltage Too Low MAP sensor input below minimum acceptable voltage.
P0108 (M) Map Sensor Voltage Too High MAP sensor input above maximum acceptable voltage.
PO111 (M) Intake Air Temp Sensor Performance
P0112 (M) Intake Air Temp Sensor Voltage Low Intake air (charge) temperature sensor input below the
minimum acceptable voltage.
P0113 (M) Intake Air Temp Sensor Voltage High Intake air (charge) temperature sensor input above the
maximum acceptable voltage.
P0116 Coolant Temp Sensor Performance A rationatilty error has been detected in the coolant temp
sensor.
P0117 (M) ECT Sensor Voltage Too Low Engine coolant temperature sensor input below the minimum
acceptable voltage.
P0118 (M) ECT Sensor Voltage Too High Engine coolant temperature sensor input above the
maximum acceptable voltage.
P0121 (M) TPS Voltage Does Not Agree With
MAPTPS signal does not correlate to MAP sensor signal.
P0121 (M) Accelerator Position Sensor (APPS)
Signal Voltage Too LowAPPS voltage input below the minimum acceptable voltage.
P0122 (M) Throttle Position Sensor Voltage Low Throttle position sensor input below the acceptable voltage
range.
P0122 (M) Accelerator Position Sensor (APPS)
Signal Voltage Too LowAPPS voltage input below the minimum acceptable voltage.
P0123 (M) Throttle Position Sensor Voltage High Throttle position sensor input above the maximum
acceptable voltage.
P0123 (M) Accelerator Position Sensor (APPS)
Signal Voltage Too HighAPPS voltage input above the maximum acceptable voltage.
BR/BEEMISSIONS CONTROL 25 - 3
EMISSIONS CONTROL (Continued)
Page 2183 of 2255

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0125 (M) Closed Loop Temp Not Reached Time to enter Closed Loop Operation (Fuel Control) is
excessive.
P0125 (M) Engine is Cold Too Long Engine does not reach operating temperature.
P0130 (M) 1/1 O2 Sensor Heater Circuit
MalfunctionOxygen sensor heater element malfunction.
P0131 (M) 1/1 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0132 (M) 1/1 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0133 (M) 1/1 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0134 (M) 1/1 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor input.
P0135 (M) 1/1 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0136 (M) 1/2 O2 Sensor Heater Circuit
MalfunctionOxygen sensor heater element malfunction.
P0137 (M) 1/2 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0138 (M) 1/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0139 (M) 1/2 O2 Sensor Slow Response Oxygen sensor response not as expected.
P0140 (M) 1/2 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0141 (M) 1/2 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0143 (M) 1/3 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0144 (M) 1/3 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0145 (M) 1/3 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0146 (M) 1/3 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0147 (M) 1/3 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
P0151 (M) 2/1 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0152 (M) 2/1 O2 Sensor Shorted To Voltage Oxygen sensor input voltage sustained above normal
operating range.
P0153 (M) 2/1 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0154 (M) 2/1 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0155 (M) 2/1 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
25 - 4 EMISSIONS CONTROLBR/BE
EMISSIONS CONTROL (Continued)
Page 2184 of 2255

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0157 (M) 2/2 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0158 (M) 2/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0159 2/2 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0160 (M) 2/2 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0161 (M) 2/2 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
PO165 Starter Relay Circuit Problem detected in starter relay circuit.
P0168 Decreased Engine Performance Due
To High Injection Pump Fuel TempFuel temperature is above the engine protection limit. Engine
power will be derated.
P0171 (M) 1/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally
rich correction factor.
P0172 (M) 1/1 Fuel System Rich A rich air/fuel mixture has been indicated by an abnormally
lean correction factor.
P0174 (M) 2/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally
rich correction factor.
P0175 (M) 2/1 Fuel System Rich A rich air/fuel mixture has been indicated by an abnormally
lean correction factor.
P0176 Loss of Flex Fuel Calibration Signal No calibration voltage present from flex fuel sensor.
P0177 Water In Fuel Excess water found in fuel by water-in-fuel sensor.
P0178 Flex Fuel Sensor Volts Too Low Flex fuel sensor input below minimum acceptable voltage.
P0178 Water In Fuel Sensor Voltage Too Low Loss of water-in-fuel circuit or sensor.
P0179 Flex Fuel Sensor Volts Too High Flex fuel sensor input above maximum acceptable voltage.
P0181 Fuel Injection Pump Failure Low power, engine derated, or engine stops.
P0182 (M) CNG Temp Sensor Voltage Too Low Compressed natural gas temperature sensor voltage below
acceptable voltage.
P0183 (M) CNG Temp Sensor Voltage Too High Compressed natural gas temperature sensor voltage above
acceptable voltage.
P0201 (M) Injector #1 Control Circuit An open or shorted condition detected in control circuit for
injector #1 or the INJ 1 injector bank.
P0202 (M) Injector #2 Control Circuit An open or shorted condition detected in control circuit for
injector #2 or the INJ 2 injector bank.
P0203 (M) Injector #3 Control Circuit An open or shorted condition detected in control circuit for
injector #3 or the INJ 3 injector bank.
P0204 (M) Injector #4 Control Circuit Injector #4 or INJ 4 injector bank output driver stage does
not respond properly to the control signal.
P0205 (M) Injector #5 Control Circuit Injector #5 output driver stage does not respond properly to
the control signal.
P0206 (M) Injector #6 Control Circuit Injector #6 output driver stage does not respond properly to
the control signal.
BR/BEEMISSIONS CONTROL 25 - 5
EMISSIONS CONTROL (Continued)