Dodge Dakota (R1). Manual — part 814
PCM DRBIII
T CODES
Generic Scan Tool Code
DRBIII
T
Scan Tool Display
P0117
Engine Coolant Volts Low
P0118
Engine Coolant Volts High
P0462
Fuel Level Sending Unit volts Too Low
P0463
Fuel Level Sending Unit volts Too High
P0500
Vehicle Speed Signal
P0522
Oil Pressure Sense Low
P0523
Oil Pressure Sense High
P0601
Internal Controller Failure
P0622
Generator Field Not Switching Properly
P1296
5 VDC Output
P1391
Loss of Cam or Crank
P1492
Ambient/Batt temp Sen Volts Too High
P1493
Ambient/Batt temp Sen Volts Too Low
P1594
Charging System Voltage Too High
P1682
Charge Output Low
P1685
SKIM Invalid Key
P1686
No SKIM Bus Message Recieved
P1687
No MIC Bus Message
P1696
PCM Failure EEPROM Write Denied
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ON-BOARD DIAGNOSTICS
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ON-BOARD DIAGNOSTICS (Continued)
EXHAUST GAS RECIRCULATION
TABLE OF CONTENTS
page
page
EXHAUST GAS RECIRCULATION
ELECTRIC VACUUM MODULATOR
EGR VALVE
TUBE
EXHAUST GAS
RECIRCULATION
DESCRIPTION
The EGR system reduces oxides of nitrogen (NOx)
in the engine exhaust. This is accomplished by allow-
ing a predetermined amount of hot exhaust gas to
recirculate and dilute the incoming fuel/air mixture.
A malfunctioning EGR system can cause engine
stumble, sags or hesitation, rough idle, engine stall-
ing and poor driveability.
DESCRIPTION - VACUUM HOSE ROUTING
SCHEMATIC
Vacuum for the EGR system is supplied by the
internal engine mounted vacuum pump. Refer to
EGR System Operation for vacuum pump informa-
tion. Vacuum harness routing for emission related
components is displayed in (Fig. 1).
OPERATION
The system consists of:
• An EGR valve assembly. The valve is located on
the side of the intake manifold.
• An Electric Vacuum Modulator (EVM). The EVM
is sometimes referred to as the EGR control solenoid
or EGR duty cycle solenoid. The EVM controls the
“on time” of the EGR valve.
• The ECM operates the EVM. The ECM is
located inside the vehicle under the instrument
panel.
Fig. 1 Typical Hose Routing
1 - EGR VALVE
2 - TO VACUUM PUMP
3 - ELECTRIC VACUUM MODULATOR (EVM)
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EXHAUST GAS RECIRCULATION
25a - 7
• An EGR tube connects a passage in the EGR
valve to the rear of the exhaust manifold.
• The vacuum pump supplies vacuum for the
EVM and the EGR valve. This pump also supplies
vacuum for operation of the power brake booster and
the heating and air conditioning system. The pump is
located internally in the front of the engine block
(Fig. 2) and is driven by the crankshaft gear.
• Vacuum lines and hoses connect the various
components.
When the ECM supplies a variable ground signal
to the EVM, EGR system operation starts to occur.
The ECM will monitor and determine when to supply
and remove this variable ground signal. This will
depend on inputs from the engine coolant tempera-
ture, throttle position and engine speed sensors.
When the variable ground signal is supplied to the
EVM, vacuum from the vacuum pump will be
allowed to pass through the EVM and on to the EGR
valve with a connecting hose.
Exhaust gas recirculation will begin in this order
when:
• The ECM determines that EGR system opera-
tion is necessary.
• The engine is running to operate the vacuum
pump.
• A variable ground signal is supplied to the EVM.
• Variable vacuum passes through the EVM to the
EGR valve.
• The inlet seat (poppet valve) at the bottom of
the EGR valve opens to dilute and recirculate
exhaust gas back into the intake manifold.
The EGR system will be shut down by the ECM
after 60 seconds of continuous engine idling to
improve idle quality.
ELECTRIC VACUUM
MODULATOR
DESCRIPTION - VACUUM TEST
With the engine running, disconnect the vacuum
supply line at the fitting on the Electric Vacuum
Modulator (EVM). Vacuum should be no less than 20
inches. If vacuum is lower, check for leaks in vacuum
supply line. If leaks cannot be found, check for low
vacuum at vacuum pump.
REMOVAL
The EVM (EGR Duty Cycle Solenoid) is mounted
behind the PCM.
(1) Disconnect the negative battery cable.
(2) Disconnect two vacuum hoses at EVM (Fig. 3).
(3) Remove mounting screws of EVM (Fig. 3).
(4) Remove the EVM to gain access to the EVM
electrical connector.
(5) Remove electrical connector at EVM.
INSTALLATION
(1) Install electrical connector to EVM.
(2) Install EVM and tighten mounting screws
(Fig. 3).
(3) Connect vacuum hoses (Fig. 3).
(4) Connect the negative battery cable.
Fig. 2 Internal Vacuum Pump
1 - INTERNAL VACUUM PUMP AND DRIVE GEAR
Fig. 3 Electric Vacuum Modulator (EVM)
1 - POWERTRAIN CONTROL MODULE (PCM)
2 - EVM HARNESS CONNECTOR
3 - ELECTRIC VACUUM MODULATOR (EVM)
4 - AIR CLEANER HOUSING
25a - 8
EXHAUST GAS RECIRCULATION
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EXHAUST GAS RECIRCULATION (Continued)
EGR VALVE
DESCRIPTION - EGR GAS FLOW TEST
Refer to the 2.5L Diesel Powertrain Diagnostic
Manual for complete test procedure.
REMOVAL
(1) Disconnect vacuum line at EGR valve vacuum
supply fitting.
(2) Loosen the tube fitting at exhaust manifold end
of EGR tube.
(3) Remove the two bolts retaining the EGR tube
to the EGR valve and remove the EGR tube.
(4) Remove the two bolts retaining the EGR valve
to the intake manifold elbow and remove EGR valve.
(5) Discard both of the old EGR mounting gaskets.
INSTALLATION
(1) Clean the intake manifold of any old gasket
material.
(2) Clean the end of EGR tube of any old gasket
material.
(3) Position the EGR valve and new gasket to the
intake manifold elbow.
(4) Install two EGR valve mounting bolts. Do not
tighten bolts at this time.
(5) Position new gasket between EGR valve and
EGR tube.
(6) Install two EGR tube bolts. Tighten all four
mounting bolts to 23 N·m (204 in. lbs.).
(7) Tighten EGR tube fitting at exhaust manifold.
(8) Connect vacuum line to EGR valve.
TUBE
REMOVAL
The EGR tube connects the EGR valve to the rear
of the exhaust manifold.
(1) Remove two EGR tube mounting bolts at EGR
valve end of tube.
(2) Loosen fitting at exhaust manifold end of tube.
(3) Remove EGR tube and discard old gasket.
(4) Clean gasket mating surfaces and EGR tube
flange gasket surfaces.
(5) Check for signs of leakage or cracked surfaces
at both ends of tube, exhaust manifold and EGR
valve.
INSTALLATION
(1) Install a new gasket to EGR valve end of EGR
tube.
(2) Position EGR tube to engine.
(3) Loosely tighten fitting at exhaust manifold end
of tube.
(4) Install 2 mounting bolts at EGR valve end of
tube. Tighten bolts to 23 N·m (204 in. lbs.) torque.
(5) Tighten fitting at exhaust manifold end of tube.
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EXHAUST GAS RECIRCULATION
25a - 9
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