TABLE OF CONTENTS
1.0 INTRODUCTION.........................................................1
1.1SYSTEM COVERAGE...............................................1
1.2SIX-STEP TROUBLESHOOTING PROCEDURE..........................1
2.0 IDENTIFICATION OF SYSTEM.............................................1
3.0 SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION......................1
3.1GENERAL DESCRIPTION............................................1
3.2FUNCTION OPERATION.............................................1
3.2.1FUEL CONTROL.............................................1
3.2.2ON-BOARD DIAGNOSTICS....................................2
3.2.3OTHER CONTROLS..........................................4
3.2.4PCM OPERATING MODES....................................4
3.2.5NON-MONITORED CIRCUITS..................................5
3.2.6SKIS OVERVIEW............................................5
3.2.7SKIM ON-BOARD DIAGNOSTICS...............................5
3.2.8SKIS OPERATION............................................6
3.2.9PROGRAMMING THE POWERTRAIN CONTROL MODULE..........6
3.2.10PROGRAMMING THE SENTRY KEY IMMOBILIZER MODULE.......7
3.2.11PROGRAMMING THE IGNITION KEYS TO THE SENTRY KEY
IMMOBILIZER MODULE.......................................7
3.3DIAGNOSTIC TROUBLE CODES......................................7
3.3.1HARD CODE................................................7
3.3.2INTERMITTENT CODE........................................8
3.3.3RESET COUNTER...........................................8
3.3.4HANDLING NO TROUBLE CODE PROBLEMS....................8
3.4USING THE DRBIIIT................................................11
3.5DRB ERROR MESSAGES AND BLANK SCREEN........................11
3.5.1DRB IIITDOES NOT POWER UP..............................11
3.5.2DISPLAY IS NOT VISIBLE....................................11
4.0 DISCLAIMERS, SAFETY, WARNINGS......................................11
4.1DISCLAIMERS.....................................................11
4.2SAFETY..........................................................11
4.2.1TECHNICIAN SAFETY INFORMATION..........................11
4.2.2VEHICLE PREPARATION FOR TESTING........................12
4.2.3SERVICING SUB-ASSEMBLIES...............................12
4.2.4DRBIIITSAFETY INFORMATION...............................12
4.3WARNINGS AND CAUTIONS........................................12
4.3.1ROAD TEST WARNINGS.....................................12
4.3.2VEHICLE DAMAGE CAUTIONS...............................12
4.3.3ELECTRONIC PINION FACTOR WARNING......................13
5.0 RECOMMENDED TOOLS AND EQUIPMENT................................13
6.0 GLOSSARY OF TERMS..................................................13
7.0 DIAGNOSTIC INFORMATION AND PROCEDURES...........................15
CHARGING
P-0622 GENERATOR FIELD NOT SWITCHING PROPERLY....................16
i
ProCarManuals.com
3.2.3 OTHER CONTROLS
CHARGING SYSTEM
The charging system is turned on when the
engine is started and ASD relay energized. When
the ASD relay is on, ASD output voltage is supplied
to the ASD sense circuit at the PCM. This voltage is
connected in some cases, through the PCM and
supplied to one of the generator field terminals
(Gen Source +). All others, the Gen field is con-
nected directly to the ASD output voltage. The
amount of current produced by the generator is
controlled by the Electronic Voltage Regulator
(EVR) circuitry, in the PCM. A battery temperature
sensor, located either in the battery tray, using the
ambient sensor, or in the PCM itself, is used to
sense battery temperature. This temperature along
with sensed line voltage, is used by the PCM to vary
the battery charging rate. This is done by cycling
the ground path to the other generator field termi-
nal (Gen field driver).
SPEED CONTROL SYSTEM
The PCM controls vehicle speed by operation of
the speed control servo vacuum and vent solenoids.
Energizing the vacuum solenoid applies vacuum to
the servo to increase throttle position. Operation of
the vent solenoid slowly releases the vacuum allow-
ing throttle position to decrease. A special dump
solenoid allows immediate release of throttle posi-
tion caused by braking, cruise control switch turned
off, shifting into neutral, excessive RPM (tires spin-
ning) or ignition key off.
3.2.4 PCM OPERATING MODES
As input signals to the powertrain control module
(PCM) change, the PCM adjusts its response to
output devices. For example, the PCM must calcu-
late a different injector pulse width and ignition
timing for idle than it does for wide open throttle.
There are several different modes of operation that
determine how the PCM responds to the various
input signals.
There are two types of engine control operation:
open loopandclosed loop.
In open loop operation, the PCM receives input
signals and responds according to preset program-
ming. Inputs from the heated oxygen sensors are
not monitored.
In closed loop operation, the PCM monitors the
inputs from the heated oxygen sensors. This input
indicates to the PCM whether or not the calculated
injector pulse width results in the ideal air-fuel
ratio of 14.7 parts air to 1 part fuel. By monitoring
the exhaust oxygen content through the oxygen
sensor, the PCM can fine tune injector pulse width.
Fine tuning injector pulse width allows the PCM toachieve the lowest emission levels while maintain-
ing optimum fuel economy.
The engine start-up (crank), engine warm-up,
and wide open throttle modes are open loop modes.
Under most operating conditions, closed loop modes
occur with the engine at operating temperature.
IGNITION SWITCH ON (ENGINE OFF) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
1. The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic
fuel strategy.
2. The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input.
The PCM modifies fuel strategy based on this
input.
When the key is in the ªonº position and the
engine is not running (zero rpm), the auto shut-
down relay and fuel pump relay are not energized.
Therefore, voltage is not supplied to the fuel pump,
ignition coil, and fuel injectors.
Engine Start-up Mode -This is an open loop
mode. The following actions occur when the starter
motor is engaged:
1. The auto shutdown and fuel pump relays are
energized. If the PCM does not receive the cam-
shaft and crankshaft signal within approxi-
mately one second, these relays are de-
energized.
2. The PCM energizes all fuel injectors until it
determines crankshaft position from the cam-
shaft and crankshaft signals. The PCM deter-
mines crankshaft position within one engine
revolution. After the crankshaft position has
been determined, the PCM energizes the fuel
injectors in sequence. The PCM adjusts the in-
jector pulse width and synchronizes the fuel
injectors by controlling the fuel injectors' ground
paths.
3. Once the engine idles within 64 rpm of its target
engine speed, the PCM compares the current
MAP sensor value with the value received dur-
ing the ignition switch on (zero rpm) mode. A
diagnostic trouble code is written to PCM mem-
ory if a minimum difference between the two
values is not found.
Once the auto shutdown and fuel pump relays
have been energized, the PCM determines the fuel
injector pulse width based on the following:
± engine coolant temperature
± manifold absolute pressure
± intake air temperature
± engine revolutions
± throttle position
4
GENERAL INFORMATION
ProCarManuals.com
to non-emission codes, they will seem like an intermit-
tent. These codes require a set of parameters to be
performed (The DRBIIItpre-test screens will help
with this for MONITOR codes), this is called a ªTRIPº.
All EURO STAGE III OBD DTCs will be set after one
or in some cases two trip failures, and the MIL will be
turned on. These codes require three successful (no
failures) TRIPS to extinguish the MIL, followed by 40
warm-up cycles to erase the code.
3.3.2 INTERMITTENT CODE
A diagnostic trouble code that is not there every
time the PCM checks the circuit is an ªintermittentº
code. Most intermittent codes are caused by wiring
or connector problems. Defects that come and go
like this are the most difficult to diagnose; they
must be looked for under specific conditions that
cause them. The following checks may assist you in
identifying a possible intermittent problem:
²Visually inspect related wire harness connectors.
Look for broken, bent, pushed out, or corroded
terminals.
²Visually inspect the related harnesses. Look for
chafed, pierced, or partially broken wire.
²Refer to any Hotline Newsletters or technical
service bulletins that may apply.
²Use the DRBIIItdata recorder or co-pilot.
²Use the DRBIIItPEP module lab scope.
3.3.3 RESET COUNTER
The reset counter counts the number of times the
vehicle has been started since codes were last set,
erased, or the battery was disconnected. The reset
counter will count up to 255 start counts.
The number of starts helps determine when the
trouble code actually happened. This is recorded by
the PCM and can be viewed on the DRBIIItas
STARTS since set.
When there are no trouble codes stored in mem-
ory, the DRBIIItwill display ªNO DTC'S Detectedº
and the reset counter will show ªSTARTS since
clear = XXX.º
3.3.4 HANDLING NO TROUBLE CODE
PROBLEMS
Symptom checks cannot be used properly unless
the driveability problem characteristic actually
happens while the vehicle is being tested.
Select the symptom that most accurately de-
scribes the vehicle's driveability problem and then
perform the test routine that pertains to this symp-
tom. Perform each routine test in sequence until the
problem is found. For definitions, see Section 6.0
Glossary of Terms.SYMPTOM DIAGNOSTIC TEST
HARD START CHECKING THE 5-VOLT
SUPPLY CIRCUIT
CHECKING SECONDARY
IGNITION SYSTEM
CHECKING ENGINE VAC-
UUM
CHECKING THE FUEL
PRESSURE
CHECKING COOLANT SEN-
SOR CALIBRATION
CHECKING THROTTLE PO-
SITION SENSOR CALIBRA-
TION
CHECKING MAP SENSOR
CALIBRATION
CHECKING THE MINIMUM
IDLE AIR FLOW
CHECKING IDLE AIR CON-
TROL MOTOR OPERATION
CHECKING ENGINE ME-
CHANICAL SYSTEMS
CHECKING EVAP EMISSION
SYSTEM
CHECKING EGR SYSTEM
CHECKING IAT SENSOR
START AND
STALLCHECKING THE 5-VOLT
SUPPLY CIRCUIT
CHECKING SECONDARY
IGNITION SYSTEM
CHECKING PCM POWER
AND GND CKT
CHECKING THE FUEL
PRESSURE
CHECKING COOLANT SEN-
SOR CALIBRATION
CHECKING THROTTLE PO-
SITION SENSOR CALIBRA-
TION
CHECKING MAP SENSOR
CALIBRATION
CHECKING THE MINIMUM
IDLE AIR FLOW
8
GENERAL INFORMATION
ProCarManuals.com
TEST ACTION APPLICABILITY
4 Turn the ignition on.
With the DRB, read the FREEZE FRAME DATA.
Using the FREEZE FRAME DATA, attempt to duplicate the condition that has set
this fault.
While using the FREEZE FRAME DATA, pay particular attention to the fault setting
conditions, such as vehicle speed, engine temperature, vehicle load, and MAP
vacuum.
Does P0121 reset?All
Ye s®Go To 6
No®Go To 5
5 Ignition Off
Start engine.
With the DRB, read the MAP Sensor voltage.
Did the MAP Sensor voltage drop from above 3.5 volts to below 2.0 volts?All
Ye s®Go To 6
No®Refer to symptom * CHECKING MAP SENSOR CALIBRATION
in the DRIVEABILITY category.
6 Ignition On, Engine Not Running
Using the schematic as a guide, wiggle the TPS Harness and Connectors to PCM.
While monitoring the DRB, observe for the TPS voltage to change.
Did the TPS voltage change at any time?All
Ye s®Repair the Harness or Connectors as necessary.
Perform Powertrain Verification Test VER-5A.
No®Go To 7
7 Ignition On, Engine Not Running
With the DRB, read the Throttle Position Sensor voltage.
Is the Throttle Position Sensor voltage above 1.0 volt?All
Ye s®Replace the Throttle Position Sensor.
Perform Powertrain Verification Test VER-5A.
No®Go To 8
8 Ignition On, Engine Not Running
While monitoring the DRB, open the Throttle Plate to wide open throttle.
Is the Throttle Position Sensor voltage above 3.5 volts?All
Ye s®Go To 9
No®Replace the Throttle Position Sensor.
Perform Powertrain Verification Test VER-5A.
9 Ignition On, Engine Not Running
While monitoring the DRB slowly open and close the Throttle Plate.
Note: You must move linkage very slowly while looking for a jump in
voltage.
Is the voltage change smooth?All
Ye s®Go To 10
No®Replace the Throttle Position Sensor.
Perform Powertrain Verification Test VER-5A.
43
DRIVEABILITY
P-0121 TPS VOLTAGE DOES NOT AGREE WITH MAP ÐContinued
ProCarManuals.com
Symptom:
P-0125 CLOSED LOOP TEMP NOT REACHED
When Monitored and Set Condition:
P-0125 CLOSED LOOP TEMP NOT REACHED
When Monitored: After engine is started, for ten minutes.
Set Condition: The engine temperature does not go above 10 degrees C (50 degrees F) by
13 minutes after the engine is started for 2 consecutive trips.
POSSIBLE CAUSES
PCM CONNECTOR AND TERM DAM, PSHD OUT, OR MISWIRED
ECT SENSOR CONN AND TERM DAM, PSHD OUT, MISWIRED
ECT SENSOR RESISTANCE >=11.00 K OHMS
PCM DEFECTIVE
THERMOSTAT DEFECTIVE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, read the FREEZE FRAME DATA.
Using the FREEZE FRAME DATA, attempt to duplicate the condition that has set
this fault.
Note that the DTC is a 2 trip failure.
Does P0121 reset?All
Ye s®Go To 3
No®Go To 2
2 The conditions required to set the DTC are no longer present.
Ensure the engine cooling system is operating properly, coolant level is at specifica-
tion, and no external or internal coolant leaks. Refer to the appropriate service
category for cooling system information.
Is the Cooling System operating correctly?All
Ye s®Test complete
No®Repair as necessary.
Perform Powertrain verification Test VER-5A
3 Ignition off.
Disconnect the ECT Sensor Connector.
Note: Check Connectors - clean/repair as necessary.
Is any Terminal damaged, pushed out, or miswired?All
Ye s®Clean or repair connector as necessary.
Perform Powertrain Verification Test VER-5A.
No®Go To 4
51
DRIVEABILITY
ProCarManuals.com
Symptom:
P-0703 BRAKE SWITCH STUCK PRESSED OR RELEASED
When Monitored and Set Condition:
P-0703 BRAKE SWITCH STUCK PRESSED OR RELEASED
When Monitored: With engine running. The PCM expects the signal to be high for 16
cycles while it monitors the brake switch signal during accel and decel modes.
Set Condition: After the vehicle speed increases, the PCM must accumulate 6 seconds
while delta throttle voltage is above 0.02 volt. The count is reset to zero whenever the
brake switch indicates a low signal.
POSSIBLE CAUSES
BRAKE SWITCH GROUND CIRCUIT OPEN
BRAKE SWITCH INTERNAL SHORT
BRAKE SWITCH SENSE CIRCUIT OPEN
BRAKE SWITCH SENSE CIRCUIT SHORT TO GROUND
PCM CONNECTOR OBSERVABLE DEFECT
PCM DEF (VOLTAGE HIGH)
PCM DEF (VOLTAGE LOW)
TEST ACTION APPLICABILITY
1 Ignition Off
Disconnect the Brake Switch Connector.
Note: Check connectors - Clean/repair as necessary.
Key on.
With a Voltmeter, measure the Brake Switch Sense Circuit at the Brake Switch
Connector.
Is the voltage above 9.0 volts?All
Ye s®Go To 2
No®Go To 5
2 Ignition Off
Disconnect the Brake Switch Connector.
Note: Check connectors - Clean/repair as necessary.
With an Ohmmeter, measure the Brake Switch Ground Circuit at the Brake Switch
Connector to ground.
Is the resistance below 5.0 ohms?All
Ye s®Go To 3
No®Repair the Brake Switch Ground Circuit.
Perform Powertrain Verification Test VER-2A.
172
DRIVEABILITY
ProCarManuals.com
TEST ACTION APPLICABILITY
3 Ignition off.
Remove the Throttle Body per service information procedure.
Note: Clean Throttle Body in a well ventilated area and wear rubber gloves.
While holding the Throttle open spray entire Throttle Body Bore with Mopar parts
cleaner.
Using a soft scuff pad, clean the Throttle Body Bore and Throttle Plate.
Using compressed air, dry the Throttle Body and install Throttle Body on Manifold.
Reconnect IAC Motor Connector and reset the IAC Motor Steps with the DRB.
Start engine and let idle.
With the DRB, actuate the minimum air flow.
Is the idle RPM within the range shown in the chart? Refer to the Service
Information.All
Ye s®Test Complete.
No®Replace the Throttle Body.
Perform Powertrain Verification Test VER-5A.
4 Ignition Off
Start engine, allow engine idle to stabilize for 60 seconds.
With the DRB, read target idle and engine RPM.
Is the engine RPM within +200/-100 RPM of target idle?All
Ye s®Go To 5
No®Go To 8
5 Ignition Off
Remove the IAC Motor from the housing.
Turn Ignition on with Engine Not Running.
With the DRB, actuate the IAC Stepper Motor.
Wiggle the Wiring Harness from the IAC Motor to the PCM.
Did the IAC stop operating at any time?All
Ye s®Repair the Harness or Connectors as necessary.
Perform Powertrain Verification Test VER-5A.
No®Go To 6
6 Ignition Off
Using the schematic as a guide, inspect the Wiring and Connectors.
Were any problems found?All
Ye s®Repair as necessary.
Perform Powertrain Verification Test VER-5A.
No®Go To 7
7 Ignition On, Engine Not Running
Check Throttle Plate and Linkage for a binding condition.
The Throttle Linkage must be free and the Throttle Plate at the idle
position.
Ensure Throttle Plate is fully closed and against its stop.
Is the Throttle Plate and Linkage okay?All
Ye s®Test Complete.
No®Repair as necessary.
Perform Powertrain Verification Test VER-5A.
181
DRIVEABILITY
P-1294 TARGET IDLE NOT REACHED ÐContinued
ProCarManuals.com
TEST ACTION APPLICABILITY
9 Ignition off.
If there are no potential causes remaining, the Powertrain Control Module is
assumed to be defective.
View repair options.All
Repair
Replace the PCM.
Perform Powertrain Verification Test VER-2A.
10 Ignition off.
Using the schematic as a guide, inspect the Wiring and Connectors.
Were any problems found?All
Ye s®Repair as necessary.
Perform Powertrain Verification Test VER-2A.
No®Go To 11
11 Start Engine.
Note: The Engine must be running before continuing test.
Wiggle Wiring Harness from ASD Relay to the Powertrain Control Module.
With the DRB, read Trouble Codes.
Did trouble code9No ASD Relay Output Voltage at PCM9reset?All
Ye s®Repair as necessary where wiggling caused the Trouble Code to be
set.
Perform Powertrain Verification Test VER-2A.
No®Test Complete.
190
DRIVEABILITY
P-1389 NO ASD RELAY OUTPUT VOLTAGE AT PCM ÐContinued
ProCarManuals.com