Dodge RAM TRUCK 1500 1995 Service Manual page 1711

B R
EMISSION CONTROL SYSTEMS 25-13
hoses are serviced as one unit. Refer to EGR Valve
Removal/Installation in this group.
(c) Remove the EGR tube between the intake
and exhaust manifolds. Check and clean the EGR
tube and its related openings on the manifolds. Re­
fer to EGR Tube in this group for procedures.
Do not attempt to clean the EGR valve. If the valve
shows evidence of heavy carbon build-up near the
base, replace it.
EGR SYSTEM TEST—3.BL/5.2L/5.9L ENGINES
WARNING- APPLY PARKING BRAKE AND/OR
B L O C K W H E E L S B E F O R E TESTING THE E G R S Y S ­
TEM.
(1) Warm up the engine and bring to operating
temperature before performing the proceeding tests.
(2) Check the condition of all EGR system hoses
and tubes for leaks, cracks, kinks and hardening of
rubber hoses. Repair and correct these conditions be­
fore performing any tests.
(3) Be sure the hoses at both the EGR valve and
EGR valve control are connected to the proper fit­
tings. Refer to figure 18.
(4) Be sure the electrical connector is firmly con­
nected at the valve control.
(5) To check EGR system operation, connect the
DRB scan tool to the data link connector. The data
link connector is located in the engine compartment
(Fig. 22). Refer to the appropriate Powertrain Diag­
nostic Procedures service manual for operation of the
DRB scan tool when diagnosing the EGR system.
POWERTRAIN CONTROL
MODULE (PCM) J9414-11
Fig. 22 PCM and Data Link Connector
(6) After checking the system with the DRB scan
tool, proceed to the following: EGR Valve Leakage
Test-3.9L/5.2L/5.9L Engine, or EGR Valve Control
Test—3.9L/5.2L/5.9L Engine and repair as necessary.
EGR VALVE LEAKAGE TEST—3.9L/5.2L/5.9L
ENGINE
This is not to be used as a complete test of the
EGR system.
If the engine will not idle, dies out on idle, or idle
is rough or slow, the poppet valve (Fig. 18) at the
base of the EGR valve may be leaking in the closed
position. The diaphragm (Fig. 18) within the EGR
valve may also be ruptured.
(1) The engine should be off for the following test.
(2) Disconnect the rubber hose from the fitting
(Fig. 18) at the top (vacuum motor) side of the EGR
valve.
(a) Connect a hand-held vacuum pump to this
fitting.
(b) Apply 15 inches of vacuum to the pump.
, (c) Observe the gauge reading on the pump.
(d) If vacuum falls off, the diaphragm in the
EGR valve has ruptured.
(e) Replace the EGR valve. Note: The EGR valve,
valve control and attaching hoses are serviced as
one unit. Refer to EGR Valve Removal/Installation
in this group.
(f) Proceed to the next step.
(3) A small metal fitting (back-pressure fitting) is
located at the base of the EGR valve (Fig. 18). A rub­
ber back-pressure hose connects it to the back-pres­
sure fitting on the EGR valve control. Disconnect this
rubber hose at the EGR valve fitting.
(4) Remove the air cleaner housing from the throt­
tle body.
(5) Using compressed air, and using an air nozzle
with a rubber tip, apply approximately 50 psi of reg­
ulated shop air to the metal back-pressure fitting on
the EGR valve.
(6) By hand, open the throttle to the wide open po­
sition. Air should not be heard emitting from the
intake manifold while applying air pressure at the
back-pressure fitting.
(7) If air can be heard emitting from the intake
manifold,. the poppet valve (Fig. 18) is leaking at the
bottom of the EGR valve. Replace the EGR valve.
Note: The EGR valve, valve control and attaching
hoses are serviced as one unit. Refer to EGR Valve
Removal/Installation in this group. Do not attempt
clean the old EGR valve.
EGR VALVE CONTROL TEST—3.9L/5.2LJ5.9L
ENGINES
TESTING ELECTRICAL SOLENOID PORTION OF VALVE
CONTROL
This is not to be used as a complete test of the
EGR system.
Electrical operation of the valve control should be
checked with the DRB scan tool. Refer to the appro-