
REMOVAL - REAR HEATER LINES
(1) Raise and support vehicle.
(2) Pinch off rubber heater line hose.
(3) Disconnect quick connect fitting at C-pillar.
(4) Loosen one screw and remove the other screw
at each of the three brackets holding the front of the
line to the underbody.
(5) Lower rear of line and drain coolant into a
suitable container.
(6) Loosen hose clamps at front of line and remove
line from vehicle.
REMOVAL - REAR AIR CONDITIONING LINES
(1) Recover A/C system.
(2) Hoist and support vehicle.
(3) Loosen one screw and remove the other screw
at each of the three brackets holding the A/C lines to
the underbody (Fig. 9).
(4) Remove both A/C lines from the two rear
retaining clamps, behind rear wheel.
(5) Remove both compression fittings at front of
A/C lines (Fig. 10).
(6) Remove (1) bolt securing A/C lines to block
located at A/C housing, behind rear wheel, and sepa-
rate block (Fig. 13).
(7) Remove rear wheel.
(8) Separate ABS harness from flex hose clamps.
(9) Remove heater lines from underbody brackets.
Fig. 10 Front Lines Connected to Rear Lines
Fig. 11 Rear Heater Hose Connection
1 - REAR HEATER HOSE
Fig. 12 Rear heater hose quick connects
1 - INSERT
2 - QUICK CONNECT
3 - COMPRESS INSERT FOR REMOVAL
Fig. 13 Rear A/C Block Connection
1 - CLEAN AREA AROUND BLOCK BEFORE REMOVAL
24 - 106 PLUMBING - REARRS
UNDERBODY LINES (Continued)

NOTE:Do not activate the Dosing Pump Prime more
than one time. This will put excess fuel in the DCHA
Heater Module an cause smoke to emit from the
DCHA exhaust pipe when heater activation occurs.
NOTE: A clicking noise heard coming from the Dos-
ing Pump indicates that the pump is operational.
(7)
With the DRBIIItin Cabin Heater, select Sys-
tem 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 DRBIIItkey pad to exit the Dosing Pump Prime.
The Dosing Pump priming procedure is now complete.
HEATER UNIT
REMOVAL
WARNING: ALLOW THE DCHA TO COOL BEFORE
PERFORMING A COMPONENT INSPECTION/REPAIR
OR REPLACEMENT. FAILURE TO FOLLOW THESE
INSTRUCTIONS MAY RESULT IN PERSONAL
INJURY.
WARNING: ALLOW THE EXHAUST SYSTEM TO
COOL BEFORE PERFORMING A COMPONENT
INSPECTION/REPAIR OR REPLACEMENT. FAILURE
TO FOLLOW THESE INSTRUCTION MAY RESULT IN
PERSONAL INJURY.
(1) Elevate the vehicle on a hoist/lift taking note of
heater exhaust tube flexible section.
(2) Drain 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 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 cross member at two locations.
(6) Disconnect the electrical connector from the
body harness near the toe board cross member and
rail.
(7) Remove the wiring harness from the toe board
cross member(Refer to 24 - HEATING & AIR CON-
DITIONING/CABIN HEATER/HEATER UNIT -
REMOVAL).
(8) Open the fuel fill 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.
(9) Loosen the two M8 fasteners at the rail. Take
care to notice that the exhaust tube bracket tab is on
top of the heater bracket.
(10) Remove the heater exhaust tube flex section
from the exhaust tube by loosening the M6 bolt of
the clamp assembly. 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 cross member.
(12) Loosen the remaining M6 and M8 fasteners
which mount the exhaust tube assembly to the vehi-
cle.
(a) Install a suitable cabin heater support device
under the cabin heater and secure the cabin heater
to the device.
(13) Loosen the remaining three M6 fasteners to
the cross members.
(14) Remove the loosened fasteners that support
the heater while supporting the weight of the heater.
(15) Swing the unit mounting bracket from
between the exhaust bracket and rail mounting loca-
tion. Drain any residual coolant from the heater unit.
(16) Lower the cabin heater and remove from the
supporting device and place on a suitable work area.
INSTALLATION
(1) Install the unit mounting bracket between the
exhaust bracket and the rail mounting location.
(2) Install the fasteners that support the heater
while supporting the weight of the heater.
(3) Install the three M6 fasteners to the cross
members. Tighten the M6 fasteners to 7 Nm (5 ft.
lbs.).
(4) Tighten the remaining M6 fasteners to 7 Nm (5
ft. lbs.) and the M8 fasteners to 23 Nm (17 ft. lbs.)
which mount the exhaust tube assembly to the vehi-
cle.
(5) Install the seat hex nut at the heater mounting
flange to the cross members. Tighten to 60 Nm (44 ft.
lbs.)
(6) Install the heater exhaust tube flex section to
the exhaust tube by tightening the M6 bolt of the
clamp assembly. Install the hose to the exhaust tube.
(7) Tighten the two M8 fasteners at the rail to 23
Nm (17 ft. lbs.). Taking care so that the exhaust tube
bracket tab is on the top of the heater bracket.
(8) Install the wiring harness(Refer to 24 - HEAT-
ING & AIR CONDITIONING/CABIN HEATER/
HEATER UNIT - INSTALLATION).
24a - 10 HEATING & AIR CONDITIONINGRG
FUEL LINE (Continued)

OPERATION
The engines use Exhaust Gas Recirculation (EGR)
systems. The EGR system reduces oxides of nitrogen
(NOx) in engine exhaust and helps prevent detona-
tion (engine knock). Under normal operating condi-tions, engine cylinder temperature can reach more
than 3000ÉF. Formation of NOx increases proportion-
ally with combustion temperature. To reduce the
emission of these oxides, the cylinder temperature
must be lowered. The system allows a predetermined
amount of hot exhaust gas to recirculate and dilute
the incoming air/fuel mixture. The diluted air/fuel
mixture reduces peak flame temperature during com-
bustion.
REMOVAL
(1) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(2) Remove front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL).
(3) Disconnect EGR valve vacuum line.
(4) Remove EGR cooler to EGR valve retaining
bolts (Fig. 1).
(5) Remove EGR valve retaining nuts (Fig. 1) and
EGR valve.
INSTALLATION
(1) Clean gasket mating surfaces.
(2) Install EGR valve (Fig. 1). Torque nuts to
32.4N´m.
(3) Connect EGR cooler to EGR valve (Fig. 1).
Torque bolts to 32.4N´m
(4) Install front wiper unit (Refer to 8 - ELECTRI-
CAL/WIPERS/WASHERS/WIPER MODULE -
INSTALLATION).
(5) Install engine cover (Refer to 9 - ENGINE -
INSTALLATION) .
VALVE COOLER
DESCRIPTION
The EGR valve on this engine uses a cooler to cool
the exhaust gases before the returned to the intake
manifold (Fig. 2). The EGR cooler attaches to the
EGR valve and is cooled with engine coolant.
REMOVAL
(1) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(2) Partially drain cooling system (Refer to 7 -
COOLING/ENGINE/COOLANT - STANDARD PRO-
CEDURE).
(3) Remove front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL) .
(4) Disconnect coolant supply and return lines at
EGR cooler (Fig. 2).
(5) Remove EGR cooler to exhaust manifold retain-
ing bolt (Fig. 2).
Fig. 1 EGR COMPONENTS
1 - HOSE CLAMP
2 - COOLANT HOSE
3 - HOSE CLAMP
4 - EGR VALVE RETAINING NUT
5 - E G R VA LV E
6 - COOLANT HOSE
7 - EGR VALVE GASKET
8 - EGR VALVE RETAINING STUDS
9 - EGR COOLER RETAINING BOLT
10 - HOSE CLAMP
11 - HOSE CLAMP
12 - EGR COOLER
13 - EGR COOLER TO EGR VALVE RETAINING BOLT
14 - TURBOCHARGER BRACKET
15 - TURBOCHARGER BRACKET RETAINING BOLT
16 - TURBOCHARGER DOWNPIPE
17 - TURBOCHARGER DOWNPIPE RETAINING NUT
18 - DOWNPIPE GASKET
19 - DOWNPIPE STUD
25a - 4 EXHAUST GAS RECIRCULATIONRG
VALVE (Continued)

responding element is applied. If a switch fails to
close, it is retested, If it fails the second test, the
code is set.
Transmission Effects:The MIL illuminates and
the transmission system defaults to Relay Open
limp-in mode.
Possible causes:
> Pressure switch sense circuit shorted to battery
between TCM and solenoid pack.
> Low line pressure
> Solenoid Pack
Name of code:P1791(35) - Loss Of Prime
When monitored:If the transmission is slipping
in any forward gear and the pressure switches are
not indicating pressure, a loss of prime test is run.
Set condition:If the transmission begins to slip in
any forward gear, and the pressure switch or
switches that should be closed for a given gear are
open, a loss of prime test begins. All available
elements (in 1st gear L-R, 2-4 and OD, in 2nd, 3rd,
and 4th gear 2-4 and OD) are turned on by the
Transmission Control Module (TCM) to see if pump
prime exists. The code is set if none of the pressure
switches respond. The TCM will continue to run the
loss of prime test until pump pressure returns.
Theory of operation:The loss of prime test is
used to prevent transmission defaults which can be
caused by a lack of pump prime.
Transmission Effects:Vehicle will not move or
transmission slips. Normal operation will continue
if pump prime returns.
Possible causes:
> Low transmission fluid level
> PRNDL indicates a valid OD code in the hydrau-
lic reverse position
> Transmission fluid filter clogged or damaged
> Transmission fluid filter improperly installed
(Bolts loose or O-ring missing)
> Oil pump - If a customer has a problem when the
transmission is cold whereby he shifts to reverse,
gets reverse, and then shifts to OD and does not
get OD (gets a neutral condition), and then can
not get reverse or OD for between 3-20 seconds,
replace the oil pump. High side clearance in the
oil pump will set a code 35. The pump will prime
upon start-up, but as the torque converter purges
air (drain down) the air will leak across the inner
rotor into the pump suction port and cause a loss
of prime right after the shift into OD. After 3- 20
seconds, pump prime will return and normal
operation will continue. The pump should be
replaced only after all other possible causes
above have been checked and verified.Name of code:P1790(36) - Fault Immediately
After Shift
When monitored:After a gear ratio error is
stored.
Set condition:This code is set if the associated
gear ratio code is stored within 1.3 seconds after a
shift.
Theory of operation:This code will only be stored
along with a 50 series code. If this code is set, it
indicates the problem is mechanical in nature.
When this code exists, diagnosing the transmission
should be based on the associated gear ratio code
and primarily mechanical causes should be consid-
ered.
Transmission Effects:None
Possible causes:
> Mechanical causes as listed under associated
gear ratio code.
Name of code:P1775(37) - Solenoid Switch Valve
Latched in TCC Position
When monitored:During an attempted shift into
1st gear.
Set condition:This code is set if three unsuccess-
ful attempts are made to get into 1st gear in one
given key start.
Theory of operation:The solenoid switch valve
(SSV) controls the direction of the transmission
fluid when the L-R/TCC solenoid is energized. The
SSV will be in the downshifted position in 1st gear,
thus directing the fluid to the L-R clutch circuit. In
2nd, 3rd, and 4th, it will be in the upshifted position
and directs the fluid into the torque converter
clutch (TCC).
When shifting into 1st gear, a special hydraulic
sequence is performed to ensure SSV movement
into the downshifted position. The L-R pressure
switch is monitored to confirm SSV movement. If
movement is not confirmed (the L-R pressure
switch does not close), 2nd gear is substituted for
1st.
Transmission Effects:Transmission will have no
1st gear (2nd gear will be substituted), and no
EMCC operation.
Possible causes:
> PRNDL indicates a valid OD code in the hydrau-
lic reverse position
> Valve body- - Solenoid valve stuck in TCC posi-
tion
> High idle speed
> Solenoid malfunction - L-R pressure switch will
not close
> L-R Pressure Switch Sense circuit shorted to
battery
10
GENERAL INFORMATION