point. The cabin heater can take up to three minutes
to completely shut down when either the heater tem-
perature is set below the lower set point or the vehi-
cle ignition is shut down.
NOTE: Do not apply a strong vacuum source such
as a garage ventilation system directly on the sup-
plemental cabin heater exhaust line. Too strong of a
vacuum can prevent the supplemental cabin heater
from starting. If required, place the vacuum source
at least 75 mm (3 in.) away from the exhaust line.
The supplemental cabin heater only operates when
the engine is running, the mileage exceeds 8 kilome-ter (5 mph) and the fuel tank volume exceeds 1/8 of a
tank. The supplemental heater control module moni-
tors blower speed and combustion during its start-up.
The cabin heater should operate if the coolant tem-
perature is below 40É C (104É F).
DIAGNOSIS AND TESTING - DIESEL
SUPPLEMENTAL CABIN HEATER
Refer to the Symptoms Diagnosis table for basic
checks of the diesel fueled supplemental cabin heater.
SYMPTOMS DIAGNOSIS
Symptom Possible Causes
Smell of diesel fuel. Check cabin heater system integration in vehicle's fuel system. Check
fuel lines for leakage, kinks or obstructions. If OK, Inspect the inlet
muffler, drain as necessary. Re-test the cabin heater and re-inspect.
Inspect the exhaust tube and cabin heater for the presence of external
fuel. If presence of external fuel is observed on the heater unit or in the
exhaust tube or after draining and testing. Remove the cabin heater
from vehicle and repair or replace components as required.
Heater does not achieve full load
operation.Check cabin heater operation with DRBIIITscan tool and replace
components as required.
Continuous white smoke from heater
exhaust during combustion operation.Check cabin heater operation with DRBIIITscan tool and replace
components as required. White smoke is typical in extreme weather
conditions.
Heater can not be switched off. Check cabin heater operation with DRBIIITscan tool and replace
components as required.
Heater does not operate. Diagnosis cabin heater control module using the DRBIIITscan tool and
the procedures listed in Vehicle Performance under Cabin Heater
Diagnosis in Group 18.
Loss of coolant (Leakage) or heater
develops smoke during combustion
operation and exhaust has an
extremely sweet smell.Inspect coolant hoses for leakage, kinks or loose hose connection.
Inspect the exhaust tube assembly for continuous flow, if OK there is an
internal heater leak and cabin heater should be inspected and
components should be replaced as required.
Loss of fuel (dripping). Check cabin heater system integration in vehicles fuel system. Check
fuel line connection for leakage. If OK there is an internal leak and
cabin heater should be inspected and replaced as required.
AIR INTAKE PIPE
REMOVAL
NOTE: The air intake tube for the supplemental
cabin heater is part of an assembly that includes
the heater cooling intake and return pipes. If the
cabin heater air intake tube requires removal or
replacement the entire cabin heater assembly will
require removal or replacement.(1) Drain the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(2) Remove clamps from the cabin heater tubes at
the lower heater port and the lower EGR connector
which are located under the hood.
(3) Remove the retaining clamp at the cabin
heater air intake muffler connection (Refer to 24 -
HEATING & AIR CONDITIONING/CABIN HEAT-
ER/INLET MUFFLER - REMOVAL).
(4) Remove the clamp at the flexible tube to steel
tube connection (Fig. 1).
RSCABIN HEATER24 - 113
CABIN HEATER (Continued)
(5) Remove the two retaining screws and remove
pipe assembly (Fig. 2).
INSTALLATION
(1) Install the air intake pipe assembly and install
the two retaining screws. Tighten the screws to 7
N´m (62 in. lbs.).
(2) Attach the steel tube to the flexible tube and
position and then tighten the retaining clamp
securely.
(3) Install the flexible tube to the cabin heater air
intake muffler and install and tighten the retaining
clamp securely.
(4) Install the cabin heater tubes to the lower
heater connection and the lower EGR cooler connec-
tion and tighten the retaining clamps.
(5) Lower the vehicle.
(6) Refill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(7) Verify function of the cabin heater.
EXHAUST TUBE
REMOVAL
WARNING: THERE IS A POTENTIAL DANGER OF
SKIN BURNS AS THE SUPPLEMENTAL CABIN
HEATER AND ITS COMPONENTS MAY BE VERY
HOT. MAKE SURE THE CABIN HEATER IS
ALLOWED TO COOL DOWN BEFORE ANY SERVICE
WORK ON THE CABIN HEATER SYSTEM IS
ATTEMPTED.
(1) Raise and support the vehicle. Take note of the
location of the flexible section of the cabin heater
exhaust tube.
(2) Remove the exhaust clamp at the flexible pipe
and steel pipe connection (Fig. 3).
(3) Remove the clamp at the flexible pipe connec-
tion and the cabin heater housing (if required).
(4) Remove the three screws holding the exhaust
pipe to the body.
(5) Remove the steel exhaust pipe from the vehi-
cle.
(6) Remove the flexible exhaust pipe from the
vehicle (if required).
Fig. 1 Cabin Heater Flexible Air Intake Line
1 - CABIN HEATER AND SPLASH SHIELD
2 - DOSING PUMP
3 - DOSING PUMP FUEL LINE
4 - FLEXIBLE INTAKE LINE
5 - CLAMP
6 - STEEL INTAKE PIPE
Fig. 2 Cabin Heater Air Intake And Heater Pipe
Assembly
1 - INTAKE TUBE AIR INTAKE
2 - INTAKE PIPE
3 - RETAINING SCREWS
4 - INTAKE HEATER LINE
5 - RETURN HEATER LINE
24 - 114 CABIN HEATERRS
AIR INTAKE PIPE (Continued)
INSTALLATION
(1) Install the flexible exhaust pipe to the cabin
heater. Tighten the mounting clamp securely.
(2) Position the steel exhaust pipe to the flexible
exhaust. Tighten the mounting clamp securely.
(3) Loosely install the three exhaust pipe screws
and adjust pipe placement as required. Tighten the
screws securely.
(4) Install the clamp that secures the steel exhaust
pipe to the flexible exhaust pipe. Tighten the clamp
securely.
(5) Check exhaust end placement of the exhaust
pipe and make any final adjustments.
(6) Lower the vehicle.
FUEL DOSING PUMP
DESCRIPTION
The dosing pump is a combined delivery, dosing
and shut-off system for the fuel supply to the supple-
mental cabin heater from the vehicle fuel tank.
OPERATION
The dosing pump is an electrically operated pump
that receives its operation instructions from the sup-
plemental cabin heater control module. The pump
supplies diesel fuel from the vehicle fuel tank to the
cabin heater.
REMOVAL
NOTE: The dosing pump is serviceable without
removing the component from the vehicle.
(1) Disconnect the rubber hose at the fuel line to
heater fuel pump. Leave the rubber hose on the fuel
line (Refer to 24 - HEATING & AIR CONDITION-
ING/CABIN HEATER/FUEL LINE - REMOVAL)
(Fig. 4).
(2) Disconnect the fuel line between the dosing
pump and the cabin heater unit.
NOTE: Position and retain the heater fuel line to
prevent fuel leakage while servicing the dosing
pump.
Fig. 3 Cabin Heater Exhaust System
1 - MOUNTING SCREWS (3)
2 - STEEL HEATER EXHAUST PIPE
3 - EXHAUST CLAMP (2)4 - FLEXIBLE HEATER EXHAUST PIPE
5 - CABIN HEATER AND SHIELD
6 - EXHAUST PIPE MOUNTING CLIPS (3) (IF EQUIPPED)
RSCABIN HEATER24 - 115
EXHAUST TUBE (Continued)
NOTE: Utilize an approved fuel storage container to
catch any residual fuel.
(3) Disconnect the wiring harness connector to the
fuel pump by depressing the integral spring and pull-
ing the connector away from the pump.
(4) Remove the dosing pump from the rubber iso-
lator.
INSTALLATION
(1) Install the dosing pump onto the rubber isola-
tor.
(2) Connect the fuel lines to the dosing pump and
the cabin heater unit.NOTE: The connectors should point towards the
cabin heater fuel line.
(3) Use aviation style clamps to attach the hose to
the fuel pump nipples (Refer to 24 - HEATING &
AIR CONDITIONING/CABIN HEATER/FUEL LINE
- INSTALLATION).
(4) Connect the wire harness connector to the fuel
pump by depressing the integral spring and pushing
the connector towards the dosing pump. Pull the con-
nector towards the cabin heater to verify the instal-
lation.
(5) Verify function of the supplemental cabin
heater.
Fig. 4 Cabin Heater Dosing Pump Fuel Line
1 - FUEL LINE
2 - RETAINING CLAMP3 - DOSING PUMP
4 - HEATER AIR INTAKE PIPE
24 - 116 CABIN HEATERRS
FUEL DOSING PUMP (Continued)
FUEL LINE
STANDARD PROCEDURE - CLEANING
(1) Remove the cabin heater fuel line (Refer to 24 -
HEATING & AIR CONDITIONING/CABIN HEAT-
ER/FUEL LINE - REMOVAL).
(2) With the cabin heater fuel line removed from
the vehicle, place a shop cloth on the fuel tank end of
the fuel line to catch any residue, then apply a small
amount of air pressure to the other end of the fuel
line.
(3) Check to see if air pressure is coming from the
tank end of the line. If pressure is flowing unre-
stricted the line is clean.
(4) If the fuel line shows any signs of being
restricted after air pressure is applied, the fuel line
should be replaced.
(5) Install the cabin heater fuel line (Refer to 24 -
HEATING & AIR CONDITIONING/CABIN HEAT-
ER/FUEL LINE - INSTALLATION).
(6) Verify function of the cabin heater.
REMOVAL
(1) Raise and support the vehicle. Take note of the
location of the flexible section of the cabin heater
exhaust tube.NOTE: Have an approved fuel holding device ready
to capture any diesel fuel that drains from the fuel
line or cabin heater unit.
(2) Remove clamps on dosing pump end of fuel line
and separate line from the pump (Fig. 5).
(3) Remove clamp from the fuel line at the fuel
tank connection and separate the line from the tank.
(4) Remove any retaining clips and remove the
fuel line from vehicle.
Fig. 5 Cabin Heater Dosing Pump Fuel Line
1 - FUEL LINE
2 - RETAINING CLAMP3 - DOSING PUMP
4 - HEATER AIR INTAKE PIPE
RSCABIN HEATER24 - 117
INSTALLATION
WARNING: DO NOT OPERATE THE DIESEL SUP-
PLEMENTAL CABIN HEATER IN AN ENCLOSED
AREA SUCH AS A GARAGE THAT DOES NOT HAVE
EXHAUST VENTILATION FACILITIES. ALWAYS VENT
THE CABIN HEATER EXHAUST WHEN OPERATING
THE CABIN HEATER. ALLOW THE DIESEL SUPPLE-
MENTAL CABIN HEATER TO COOL BEFORE PER-
FORMING ANY SERVICE PROCEDURES TO THE
CABIN HEATER. VERIFY THAT ALL DIESEL SUP-
PLEMENTAL CABIN HEATER FUEL LINES ARE
SECURELY FASTENED TO THEIR RESPECTIVE
COMPONENTS BEFORE PERFORMING ANY SER-
VICE PROCEDURES TO THE CABIN HEATER. FAIL-
URE TO FOLLOW THESE INSTRUCTION MAY
RESULT IN PERSONAL INJURY OR DEATH.
NOTE: Verify that there is more than 1/8 of a tank of
fuel in the vehicle's fuel tank before performing this
procedure. Add fuel, if necessary.
(1) Install the cabin heater fuel supply line into
vehicle and fuel line retainers.
(2) Install the fuel line connection at the fuel tank
and tighten the connection securely.
(3) Install the fuel line at the dosing pump and
tighten the connection securely.
(4) Lower the vehicle.
NOTE: Failure to prime the dosing pump after drain-
ing the supplemental cabin fuel line will prevent
cabin heater activation during the first attempt to
start the cabin heater. This will also set a diagnostic
trouble code (DTC) in the cabin heater control's
memory. Do not perform the Dosing Pump Priming
procedure if an attempt was made to start the cabin
heater without priming the dosing pump first. This
will put excess fuel in the cabin heater and cause
smoke to emit from the cabin heater exhaust pipe
when cabin heater activation occurs.
(5) Connect the DRBIIItscan tool to the diagnos-
tic link connector.
(6) Turn the ignition to the ON position.
NOTE: Do not activate the dosing pump prime more
than one time. This will put excess fuel in the sup-
plemental cabin heater and cause smoke to emit
from the cabin heater exhaust pipe when cabin
heater activation occurs.
NOTE: A clicking noise heard coming from the dos-
ing pump indicates that the pump is operational.(7) With the DRBIIItscan tool in Cabin Heater,
select System Tests and Dosing Pump Prime. Allow
the dosing pump to run for the full 45 second cycle
time. When the 45 second cycle is complete, press
Page Back on the DRBIIItscan tool key pad to exit
the Dosing Pump Prime. The Dosing Pump Priming
procedure is now complete.
HEATER UNIT
REMOVAL
WARNING: DO NOT OPERATE THE DIESEL SUP-
PLEMENTAL CABIN HEATER IN AN ENCLOSED
AREA SUCH AS A GARAGE THAT DOES NOT HAVE
EXHAUST VENTILATION FACILITIES. ALWAYS VENT
THE CABIN HEATER EXHAUST WHEN OPERATING
THE CABIN HEATER. ALLOW THE DIESEL SUPPLE-
MENTAL CABIN HEATER TO COOL BEFORE PER-
FORMING ANY SERVICE PROCEDURES TO THE
CABIN HEATER. VERIFY THAT ALL DIESEL SUP-
PLEMENTAL CABIN HEATER FUEL LINES ARE
SECURELY FASTENED TO THEIR RESPECTIVE
COMPONENTS BEFORE PERFORMING ANY SER-
VICE PROCEDURES TO THE CABIN HEATER. FAIL-
URE TO FOLLOW THESE INSTRUCTION MAY
RESULT IN PERSONAL INJURY OR DEATH.
(1) Raise and support the vehicle. Take note of the
location of the flexible section of the cabin heater
exhaust tube.
(2) Drain the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(3) Carefully open one hose to the underbody tube
assembly and drain the remaining coolant. A salvage
hose is a good idea to control the residual coolant, as
flow will occur from both the cabin heater and the
hose and tube assemblies.
(4) Remove the second hose from the underbody
hose and tube assembly.
(5) Loosen the hose and tube assembly from the
toe-board crossmember at two locations.
(6) Disconnect the electrical connector from the
body harness near the toe-board crossmember and
rail.
(7) Remove the wiring harness from the toe-board
crossmember (Refer to 24 - HEATING & AIR CON-
DITIONING/CABIN HEATER/HEATER UNIT -
REMOVAL).
(8) Open the fuel filler cap. Disconnect the rubber
fuel hose between the body tube assembly and the
fuel pump nipple at the body tube joint. A minimal
amount of fuel may flow from the open port.
NOTE: Utilize an approved fuel storage container to
catch any residual fuel.
24 - 118 CABIN HEATERRS
FUEL LINE (Continued)
(9) Loosen the two fasteners at the rail. Take care
to notice that the exhaust tube bracket tab is on top
of the heater bracket and that there are two spacer
washers installed between the rubber grommets.
(10) Remove the flexible section of the cabin
heater exhaust tube from the exhaust tube by loos-
ening the clamp. Remove the hose from the exhaust
tube. Removal of the rail tube assembly may aid in
this service operation (Refer to 24 - HEATING & AIR
CONDITIONING/CABIN HEATER/EXHAUST TUBE
- REMOVAL).
(11) Remove seat hex nut at the heater mounting
flange to crossmember.
(12) Loosen the remaining fasteners which mount
the exhaust tube assembly to the vehicle.
(a) Install a suitable support device under the
cabin heater and secure the cabin heater to the
support.
(13) Loosen the remaining three fasteners to the
crossmembers.
(14) Remove the loosened fasteners that support
the cabin heater while supporting the weight of the
heater.
(15) Swing the cabin heater mounting bracket
from between the exhaust bracket and rail mounting
location. Drain any residual coolant from the cabin
heater.
(16) Remove the cabin heater from the vehicle.
INSTALLATION
(1) Install the cabin heater mounting bracket
between the exhaust bracket and the rail mounting
location.
(2) Support the cabin heater and install the fasten-
ers that secure the cabin heater to the mounting
bracket.
(3) Install the three fasteners to the crossmem-
bers. Tighten the M6 fasteners to 7 N´m (62 in. lbs.).
(4) Position the two spacer washers between the
body and the rubber grommets for the two mounting
points on the rail.
(5) Tighten the remaining M6 fasteners to 7 N´m
(62 in. lbs.) and the M8 fasteners to 23 N´m (17 ft.
lbs.) which mount the exhaust tube assembly to the
vehicle.
(6) Install the seat hex nut at the heater mounting
flange to the crossmembers. Tighten the nut to 60
N´m (44 ft. lbs.)
(7) Install the flexible section of the cabin heater
exhaust tube to the exhaust tube. Tighten the M6
bolt of the clamp securley. Install the hose to the
exhaust tube.
(8) Tighten the two M8 fasteners at the rail to 23
N´m (17 ft. lbs.). Taking care so that the exhaust
tube bracket tab is on the top of the heater bracket.(9) Install the wiring harness (Refer to 24 - HEAT-
ING & AIR CONDITIONING/CABIN HEATER/
HEATER UNIT - INSTALLATION).
(10) Tighten the hose and tube assembly to the
toe-board crossmember at two locations.
(11) Install the second hose to the underbody hose
and tube assembly.
(12) Connect the rubber fuel hose between the
body tube assembly and the fuel pump nipple at the
body tube joint. Close the fuel fill cap.
(13) Remove the cabin heater support device from
under the vehicle.
(14) Lower the vehicle.
(15) Fill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(16) Verify function of the cabin heater.
SUPPLEMENTAL DIESEL
HEATER WIRING
REMOVAL
(1) Elevate vehicle on a lift taking note of the
exhaust tube flexible section.
(2) Unplug connector from vehicle wiring harness
to cabin heater harness.
(3) Unplug connector from cabin heater harness to
dosing pump connector.
(4) Unplug two connectors from cabin heater har-
ness to cabin heater controller connectors.
(5) Remove two wiring harness connectors from
underbody.
(6) Remove two wiring harness connectors from
cabin heater shield.
(7) Carefully route the cabin heater harness to the
left side between the cabin heater unit and the cabin
heater shield.
INSTALLATION
(1) Carefully route the cabin heater harness from
the left side of the cabin heater between the cabin
heater unit and the cabin heater shield.
(2) Install the two wiring harness retaining con-
nectors to the cabin heater shield.
(3) Route the wiring harness along the underside
of the vehicle and install the two wiring harness
retaining connectors.
(4) Plug the two connectors from the cabin heater
harness to the cabin heater controller.
(5) Plug the connector to the cabin heater harness
to the dosing pump connector.
(6) Plug the connector from the vehicle wiring har-
ness to the cabin heater harness.
(7) Lower the vehicle.
(8) Verify function of the cabin heater.
RSCABIN HEATER24 - 119
HEATER UNIT (Continued)
The following is a list of the monitored compo-
nents:
²Comprehensive Components
²Oxygen Sensor Monitor
²Oxygen Sensor Heater Monitor
²Catalyst Monitor
COMPREHENSIVE COMPONENTS
Along with the major monitors, OBD II requires
that the diagnostic system monitor any component
that could affect emissions levels. In many cases,
these components were being tested under OBD I.
The OBD I requirements focused mainly on testing
emissions-related components for electrical opens and
shorts.
However, OBD II also requires that inputs from
powertrain components to the PCM be tested for
rationality, and that outputs to powertrain compo-
nents from the PCM be tested forfunctionality.
Methods for monitoring the various Comprehensive
Component monitoring include:
(1) Circuit Continuity
²Open
²Shorted high
²Shorted to ground
(2) Rationality or Proper Functioning
²Inputs tested for rationality
²Outputs tested for functionality
NOTE: Comprehensive component monitors are
continuous. Therefore, enabling conditions do not
apply.
Input RationalityÐWhile input signals to the
PCM are constantly being monitored for electrical
opens and shorts, they are also tested for rationality.
This means that the input signal is compared against
other inputs and information to see if it makes sense
under the current conditions.
PCM sensor inputs that are checked for rationality
include:
²Manifold Absolute Pressure (MAP) Sensor
²Oxygen Sensor (O2S)
²Engine Coolant Temperature (ECT) Sensor
²Camshaft Position (CMP) Sensor
²Vehicle Speed Sensor
²Crankshaft Position (CKP) Sensor
²Intake/inlet Air Temperature (IAT) Sensor
²Throttle Position (TPS) Sensor
²Ambient Temperature Sensors
²Power Steering Switch
²Oxygen Sensor Heater
²Brake Switch
²Leak Detection Pump Switch or NVLD switch (if
equipped)
²P/N SwitchOutput FunctionalityÐPCM outputs are tested
for functionality in addition to testing for opens and
shorts. When the PCM provides a voltage to an out-
put component, it can verify that the command was
carried out by monitoring specific input signals for
expected changes. For example, when the PCM com-
mands the Idle Air Control (IAC) Motor to a specific
position under certain operating conditions, it expects
to see a specific (target) idle speed (RPM). If it does
not, it stores a DTC.
PCM outputs monitored for functionality include:
²Fuel Injectors
²Ignition Coils
²Idle Air Control
²Purge Solenoid
²EGR Solenoid (if equipped)
²LDP Solenoid or NVLD solenoid (if equipped)
²Radiator Fan Control
²Trans Controls
OXYGEN SENSOR (O2S) MONITOR
DESCRIPTIONÐEffective control of exhaust
emissions is achieved by an oxygen feedback system.
The most important element of the feedback system
is the O2S. The O2S is located in the exhaust path.
Once it reaches operating temperature 300É to 350ÉC
(572É to 662ÉF), the sensor generates a voltage that
is inversely proportional to the amount of oxygen in
the exhaust. When there is a large amount of oxygen
in the exhaust caused by a lean condition, the sensor
produces a low voltage, below 450 mV. When the oxy-
gen content is lower, caused by a rich condition, the
sensor produces a higher voltage, above 450mV (volt-
ages are offset by 2.5 volts on NGC vehicles).
The information obtained by the sensor is used to
calculate the fuel injector pulse width. The PCM is
programmed to maintain the optimum air/fuel ratio.
At this mixture ratio, the catalyst works best to
remove hydrocarbons (HC), carbon monoxide (CO)
and nitrous oxide (NOx) from the exhaust.
The O2S is also the main sensing element for the
EGR (if equipped), Catalyst and Fuel Monitors.
The O2S may fail in any or all of the following
manners:
²Slow response rate (Big Slope)
²Reduced output voltage (Half Cycle)
²Heater Performance
Slow Response Rate (Big Slope)ÐResponse rate
is the time required for the sensor to switch from
lean to rich signal output once it is exposed to a
richer than optimum A/F mixture or vice versa. As
the PCM adjusts the air/fuel ratio, the sensor must
be able to rapidly detect the change. As the sensor
ages, it could take longer to detect the changes in the
oxygen content of the exhaust gas. The rate of
change that an oxygen sensor experiences is called
25 - 2 EMISSIONS CONTROLRS
EMISSIONS CONTROL (Continued)