CHECKING FOR OXYGEN
SENSOR SWITCHING
CHECKING O2S HEATER
CHECKING IDLE AIR CON-
TROL MOTOR OPERATION
CHECKING ENGINE ME-
CHANICAL SYSTEMS
CHECKING EVAP EMISSION
SYSTEM
CHECKING EGR SYSTEM
CHECKING IAT SENSOR
CHECKING PNP SWITCH
3.4 USING THE DRBIIIT
Refer to the DRBIIItuser 's guide for instructions
and assistance with reading trouble codes, erasing
trouble codes, and other DRBIIItfunctions.
3.5 DRB ERROR MESSAGES AND BLANK
SCREEN
Under normal operation, the DRBIIItwill dis-
play one of only two error messages:
± User-Requested WARM Boot or User-
Requested COLD Boot.
This is a sample of such an error message display:
ver: 2.14
date: 26 Jul93
file: key_itf.cc
date: Jul 26 1993
line: 548
err: 0x1
User-Requested COLD Boot
Press MORE to switch between this display
and the application screen.
Press F4 when done noting information.
3.5.1 DRB IIITDOES NOT POWER UP
If the LED's do not light or no sound is emitted at
start up, check for loose cable connections or a bad
cable. Check the vehicle battery voltage (data link
connector cavity 16). A minimum of 11 volts is
required to adequately power the DRBIIIt.
If all connections are proper between the
DRBIIItand vehicle or other devices, and the
vehicle battery is fully charged, an inoperative
DRBIIItmay be the result of a faulty cable or
vehicle wiring. For a blank screen, refer to the
appropriate body diagnostics manual.
3.5.2 DISPLAY IS NOT VISIBLE
Low temperatures will affect the visibility of the
display. Adjust the contrast to compensate for this
condition.
4.0 DISCLAIMERS, SAFETY,
WARNINGS
4.1 DISCLAIMERS
All information, illustrations, and specifications
contained in this manual are based on the latest
information available at the time of publication.
The right is reserved to make changes at any time
without notice.
4.2 SAFETY
4.2.1 TECHNICIAN SAFETY INFORMATION
WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING, KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.
Set the parking brake and block the wheels before
testing or repairing the vehicle. It is especially impor-
tant to block the wheels on front-wheel drive vehicles;
the parking brake does not hold the drive wheels.
When servicing a vehicle, always wear eye pro-
tection, and remove any metal jewelry such as
watchbands or bracelets that might make an inad-
vertent electrical contact.
When diagnosing a powertrain system problem,
it is important to follow approved procedures where
11
GENERAL INFORMATION
ProCarManuals.com
TEST ACTION APPLICABILITY
12 Engine Off.
Connect a suitable engine analyzer to the engine.
Allow the Engine to idle.
NOTE: If the Engine will not idle, maintain a constant RPM above idle.
NOTE: Set the scope to read display or parade pattern.
Remove any spark plug wire.
Observe the Secondary KV Line.
Is the open secondary voltage at least 25 KV?All
Ye s®Go To 13
No®Replace the Ignition Coil.
Perform VERIFICATION TEST VER-5A2.
13 Engine Off.
Connect a suitable engine analyzer to the engine.
Allow the Engine to idle.
NOTE: If the Engine will not idle, maintain a constant RPM above idle.
NOTE: Set the scope to read display or parade pattern.
Follow the equipment manufacturer's procedure for pattern analysis.
Is the secondary ignition pattern OK?All
Ye s®Go To 14
No®Repair the indicated component in the Secondary Ignition Sys-
tem.
Perform VERIFICATION TEST VER-5A2.
14 The following are possible causes for mis-fire:
Injector harness connectors, ignition coil circuit, spark plug, mechanical engine
problem, PCM power grounds, irregular cam and crank signal, injectors, restricted
exhaust, intake restriction, PCM, Evap System, EGR System, damaged trigger
wheel, and
accessory drive belts.
Do any of the above causes exist?All
Ye s®Repair as necessary.
Perform VERIFICATION TEST VER-5A2.
No®Go To 15
15The following additional items should be checked as possible mechanical
problems:
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions
ENGINE PCV SYSTEM - must flow freely
ENGINE DRIVE SPROCKETS - must be properly positioned
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connected to
correct injector
Are there any engine mechanical problems?All
Ye s®Repair as necessary.
Perform VERIFICATION TEST VER-5A2.
No®Test Complete.
103
DRIVEABILITY
P-0300 MULTIPLE CYLINDER MIS-FIRE ÐContinued
ProCarManuals.com
TEST ACTION APPLICABILITY
12 Engine Off.
Connect a suitable engine analyzer to the engine.
Allow the Engine to idle.
NOTE: If the Engine will not idle, maintain a constant RPM above idle.
NOTE: Set the scope to read display or parade pattern.
Follow the equipment manufacturer's procedure for pattern analysis.
Is the secondary ignition pattern OK?ENGINE - 3.0L V6
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
and/or ENGINE -
3.3L V6 FFV
Ye s®Go To 13
No®Repair the indicated component in the Secondary Ignition Sys-
tem.
Perform VERIFICATION TEST VER-5A2.
13 With the DRB, read the FREEZE FRAME DATA.
Use the freeze frame data and attempt to determine the cause of the misfire.
In the FREEZE FRAME, is the ENGINE RPM over 3000 and the operating temp
normal?ENGINE - 3.0L V6
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
and/or ENGINE -
3.3L V6 FFV
Ye s®Lab scope cam and crank sensor, check valve timing, running
vacuum test.
Perform VERIFICATION TEST VER-5A2.
No®Go To 14
14The following additional items should be checked as possible mechanical
problems:
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions
ENGINE PCV SYSTEM - must flow freely
ENGINE DRIVE SPROCKETS - must be properly positioned
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connected to
correct injector
Are there any engine mechanical problems?ENGINE - 3.0L V6
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
and/or ENGINE -
3.3L V6 FFV
Ye s®Repair as necessary.
Perform VERIFICATION TEST VER-5A2.
No®Go To 15
15 The following are other possible causes for mis-fire:
Injector harness connectors, ignition coil circuit, spark plug, mechanical engine
problem, PCM power grounds, irregular cam and crank signal, injectors, restricted
exhaust, intake restriction, PCM, Evap System, EGR System, damaged trigger
wheel, and
accessory drive belts.
Do any of the above causes exist?ENGINE - 3.0L V6
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
and/or ENGINE -
3.3L V6 FFV
Ye s®Repair as necessary.
Perform VERIFICATION TEST VER-5A2.
No®Test Complete.
107
DRIVEABILITY
P-0305 CYLINDER #5 MIS-FIRE ÐContinued
ProCarManuals.com
Symptom:
P-0320 NO CRANK REFERENCE SIGNAL AT PCM
When Monitored and Set Condition:
P-0320 NO CRANK REFERENCE SIGNAL AT PCM
When Monitored: During cranking, with battery voltage between 4.0 volts and 11.6 volts
and manifold vacuum present.
Set Condition: No signal from the crank position sensor is present during engine
cranking or the cam position signal is present with no crank signal.
POSSIBLE CAUSES
CKP SENSOR DEFECTIVE
CRANK POSITION SENSOR GROUND CIRCUIT OPEN
CRANKSHAFT NOTCHES DAMAGED
FLYWHEEL DAMAGED
8-VOLT SUPPLY CIRCUIT OPEN
8-VOLT SUPPLY CIRCUIT SHORT TO GROUND
CKP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
CMP/CKP SENSOR WIRING HARNESS INTERMITTENT DEFECT
CMP/CKP SENSOR WIRING HARNESS OBSERVABLE DEFECT
CRANK POSITION SENSOR SIGNAL CIRCUIT OPEN
PCM DEFECTIVE
PCM DEFECTIVE (NO CRANK REF SIG)
TEST ACTION APPLICABILITY
1 Cycle the ignition off, then on.
Attempt to start engine.
With the DRB in Input/Output display, read the current CMP and CKP states.
Did the CMP or CKP states change to present while cranking engine?All
Ye s®Go To 2
No®Go To 6
2 Cycle the ignition off, then on.
Attempt to start engine.
With the DRB in Input/Output display, read the current CMP and CKP states.
Did only the CMP state change while cranking engine?All
Ye s®Go To 6
No®Go To 3
108
DRIVEABILITY
ProCarManuals.com
TEST ACTION APPLICABILITY
8 Ignition Off
Disconnect the Crank Position (CKP) Sensor Connector.
Note: Check connectors - Clean/repair as necessary.
Connect one end of a jumper wire to the Crank Position Signal Circuit.
Turn ignition on.
With the DRB, monitor the current CKP state.
Tap the other end of jumper to Sensor ground several times.
Does the CKP state change to present?All
Ye s®Go To 9
No®Go To 10
9 Ignition Off
Remove the Crankshaft Position (CKP) Sensor.
Inspect the Flywheel for damage. (3.0L, 3.3L and 3.8L)
Inspect the Crankshaft Notches for debris or damage.
Is the Flywheel damaged?All
Ye s®Repair as necessary.
Perform Powertrain Verification Test VER-2A.
No®Replace the Crankshaft Position Sensor.
Perform Powertrain Verification Test VER-2A.
10 Ignition Off
Disconnect the Crank Position (CKP) Sensor Connector.
Note: Check connectors - Clean/repair as necessary.
Disconnect the Powertrain Control Module Connector.
Note: Check connectors - Clean/repair as necessary.
Using an Ohmmeter, measure resistance of the CKP Signal Circuit to a good ground.
Is the resistance below 5.0 ohms?All
Ye s®Repair the Crank Position Sensor Signal Circuit for a short to
ground. Note: Check TCM for short.
Perform Powertrain Verification Test VER-2A.
No®Go To 11
11 Ignition Off
Disconnect the Crank Position (CKP) Sensor Connector.
Note: Check connectors - Clean/repair as necessary.
Disconnect the Powertrain Control Module Connector.
Note: Check connectors - Clean/repair as necessary.
Using an Ohmmeter, measure the resistance of the CKP Sensor Signal Circuit from
the CKP Sensor Connector to the PCM Connector.
Is the resistance below 5.0 ohms?All
Ye s®Go To 12
No®Repair the open Crank Position Sensor Signal Circuit.
Perform Powertrain Verification Test VER-2A.
11 0
DRIVEABILITY
P-0320 NO CRANK REFERENCE SIGNAL AT PCM ÐContinued
ProCarManuals.com
TEST ACTION APPLICABILITY
1 Ignition Off
Raise the Drive Wheels off the ground.
Warning: Be sure to keep hands and feet clear of rotating wheels.
Start Engine.
With DRB, read the Vehicle Speed Sensor.
Put Transmission on any forward gear.
Does the DRB show above zero MPH?ENGINE - 2.0L,
2.4L I-4 DOHC
and/or ENGINE -
3.0L V6 w/o EATX
Ye s®Go To 2
No®Go To 3
2 Ignition off.
Using the Schematic as a guide, inspect the Wiring and Connectors.
Were any problems found?ENGINE -2.0L,
2.4L I-4 DOHC
and/or ENGINE -
3.0L V6 w/o EATX
Ye s®Repair as necessary.
Perform Powertrain Verification Test VER-5A.
No®Test Complete.
3 Ignition Off
Disconnect the VSS Connector.
Note: Check connectors - Clean/repair as necessary.
Key On
Using a Voltmeter, probe the 8-Volt Power Supply Circuit.
Is the voltage above 7.0 volts?ENGINE - 2.0L,
2.4L I-4 DOHC
and/or ENGINE -
3.0L V6 w/o EATX
Ye s®Go To 4
No®Repair the open 8-volt Supply Circuit.
Perform Powertrain Verification Test VER-5A.
4 Ignition Off
Disconnect the VSS Connector.
Note: Check connectors - Clean/repair as necessary.
Key On.
Using a Voltmeter, Probe the Vehicle Speed Sensor Signal.
Is the voltage above 4.0 volts?ENGINE - 2.0L,
2.4L I-4 DOHC
and/or ENGINE -
3.0L V6 w/o EATX
Ye s®Go To 5
No®Go To 11
5 Ignition Off
Disconnect the VSS Connector.
Note: Check connectors - Clean/repair as necessary.
Connect a jumper wire from the Sensor Signal to the Sensor Ground Circuit.
Key On
With the DRB, read the VSS Signal.
While observing display, tap other end of jumper to VSS Signal Circuit.
Does the display show more than 0 MPH?ENGINE - 2.0L,
2.4L I-4 DOHC
and/or ENGINE -
3.0L V6 w/o EATX
Ye s®Go To 6
No®Go To 8
154
DRIVEABILITY
P-0500 NO VEHICLE SPEED SENSOR SIGNAL ÐContinued
ProCarManuals.com
TEST ACTION APPLICABILITY
12 Ignition Off
Disconnect the VSS Connector.
Disconnect the Powertrain Control Module.
Note: Check connectors - Clean/repair as necessary.
With the DRB in Ohmmeter mode, measure between the VSS Signal Circuit in the
Powertrain Control Module Connector.
Is the resistance below 5.0 ohms?ENGINE -2.0L,
2.4L I-4 DOHC
and/or ENGINE -
3.0L V6 w/o EATX
Ye s®Repair the Speed Sensor Signal Circuit for a short to ground.
Perform Powertrain Verification Test VER-5A.
No®Go To 13
13 If there are no potential causes remaining, the Powertrain Control Module is
assumed to be defective.
View repair options.ENGINE - 2.0L,
2.4L I-4 DOHC
and/or ENGINE -
3.0L V6 w/o EATX Repair
Replace the Powertrain Control Module.
Perform Powertrain Verification Test VER-5A.
14 Ignition Off
Raise the Drive Wheels off the ground.
Warning: Be sure to keep hands and feet clear of rotating wheels.
Start Engine.
With DRB, read the Vehicle Speed Sensor.
Put Transmission on any forward gear.
Does the DRB show above zero MPH?ENGINE -2.0L,
2.4L, 3.3L V6 FFV
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
w/EATX
Ye s®Go To 15
No®Go To 16
15 Ignition off.
Using the Schematic as a guide, inspect the Wiring and Connectors.
Were any problems found?ENGINE - 2.0L,
2.4L, 3.3L V6 FFV
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
w/EATX Ye s®Repair as necessary.
Perform Powertrain Verification Test VER-5A.
No®Test Complete.
16 Ignition On, Engine Not Running
With the DRB, read the EATX Trouble Codes.
Are any codes P0731- P0734, P0736, P0715, P0720, P1794 present or Pinion Factor
not programmed?ENGINE - 2.0L,
2.4L, 3.3L V6 FFV
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
w/EATX Ye s®Refer to the symptom list for problems related to Transmission.
No®Go To 17
17 Ignition Off
Disconnect the Transmission Control Module.
Note: Check connectors - Clean/repair as necessary.
Connect a Jumper Wire to the VSS Signal Circuit.
Key on.
With the DRB, read the VSS Signal.
While observing display, tap the other end of Jumper to ground.
Does the display show above zero MPH?ENGINE - 2.0L,
2.4L, 3.3L V6 FFV
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
w/EATX
Ye s®Go To 18
No®Go To 25
156
DRIVEABILITY
P-0500 NO VEHICLE SPEED SENSOR SIGNAL ÐContinued
ProCarManuals.com
Symptom:
P-1391 INTERMITTENT LOSS OF CMP OR CKP
When Monitored and Set Condition:
P-1391 INTERMITTENT LOSS OF CMP OR CKP
When Monitored: Engine running over 7 seconds.
Set Condition: When the expected cam signal level disagrees with the actual cam signal
level.
POSSIBLE CAUSES
CKP SENSOR CKT WIRING HARNESS INTER DEF
CMP SENSOR SIGNAL CKT WIRING HARNESS INTER DEF
CAMSHAFT POSITION SENSOR DEFECTIVE
CAMSHAFT SPROCKET DEFECTIVE
CRANKSHAFT DEFECTIVE
CRANKSHAFT POSITION SENSOR DEFECTIVE
DISTRIBUTOR PULSE RING DEFECTIVE
FLYWHEEL DEFECTIVE
CAMSHAFT TARGET MAGNET DEFECTIVE
CAMSHAFT THRUST PLATES(S) NOT ATTACHED
CKP SENSOR CONNECTOR TERMINALS OBS DEF
CKP SENSOR CONNECTOR TERMINALS OBS DEFECT
PCM CONN TERMINALS OBS DEF (CKP SENSOR)
PCM CONN TERMINALS OBS DEF (CMP SENSOR)
CAMSHAFT/CYLINDER HEAD DEFECTIVE
TEST ACTION APPLICABILITY
1 Ignition Off.
At the CMP Sensor, backprobe the CMP Sensor Signal Circuit with the Oscilloscope
voltage measurement lead.
Start the Engine and observe the CMP Sensor voltage pattern on the Oscilloscope.
Are there any of the Camshaft Position Sensor Signals missing?ENGINE - 3.3L V6
and/or ENGINE -
3.8L V6 and/or EN-
GINE - 3.3L V6
FFV
Ye s®Go To 2
No®Go To 6
191
DRIVEABILITY
ProCarManuals.com