SYMPTOM DIAGNOSTIC TEST
POOR FUEL ECONOMY CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING ECT SENSOR
CHECKING THROTTLE POSITION SENSOR
CHECKING MAP SENSOR
CHECKING IDLE AIR CONTROL MOTOR OPERATION
CHECKING IAT SENSOR
3.4 USING THE DRBIIIT
Refer to the DRBIIItuser 's guide for instructions
and assistance with reading DTC's, erasing DTC's,
and other DRBIIItfunctions.
3.5 DRBIIITERROR 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
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 DRBIIITDOES 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 the vehicle or other devices, and the
vehicle battery is fully charged, and inoperative
DRBIIItmay be the result of faulty cable or vehicle
wiring.
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
10
GENERAL INFORMATION
When testing voltage or continuity at any control
module, use the terminal side (not the wire end) of
the connector. Do not probe a wire through the
insulation; this will damage it and eventually cause
it to fail because of corrosion.
Be careful when performing electrical tests so as
to prevent accidental shorting of terminals. Such
mistakes can damage fuses or components. Also, a
second DTC could be set, making diagnosis of the
original problem more difficult.
5.0 REQUIRED TOOLS AND
EQUIPMENT
DRBIIIt(diagnostic read-out box) scan tool
Evaporative System Diagnostic Kit #6917
fuel filler adapter #8382
fuel pressure adapter (C-6631) or #6539
fuel pressure kit (C-4799-B) or #5069
fuel release hose (C-4799-1)
Min Air flow fitting #6714
jumper wires
ohmmeter
oscilloscope
vacuum gauge
voltmeter
12 volt test light minimum 25 ohms resistance
with probe #6801
CAUTION: A 12 VOLT TEST LIGHT SHOULD
NOT BE USED FOR THE FOLLOWING
CIRCUITS, DAMAGE TO THE POWERTRAIN
CONTROLLER WILL OCCUR.
²5 Volt Supply
²8 Volt Supply
²J1850 PCI Bus
²CCD Bus
²CKP Sensor Signal
²CMP Sensor Signal
²Vehicle Speed Sensor Signal
²O2 Sensor Signal
6.0 GLOSSARY OF TERMS
ABSanti-lock brake system
backfire,
popbackfuel ignites in either the intake or
the exhaust system
CKPcrank position sensor
CMPcamshaft position sensorcuts out,
missesa steady pulsation or the inability of
the engine to maintain a consistent
rpm
DLCdata link connector (previously
called engine diagnostic connector)
detona-
tion,
spark
knocka mild to severe ping, especially un-
der loaded engine conditions
ECTengine coolant temperature sensor
EGRexhaust gas recirculation valve
genera-
torpreviously called alternator
hard
startThe engine takes longer than usual
to start, even though it is able to
crank normally.
hesita-
tion, sag,
stumbleThere is a momentary lack of re-
sponse when the throttle is opened.
This can occur at all vehicle speeds.
If it is severe enough, the engine
may stall.
IATintake air temperature sensor
IACidle air control motor
JTECCombined engine and transmission
control module
lack of
power,
sluggishThe engine has less than expected
power, with little or no increase in
vehicle speed when the throttle is
opened.
LDPleak detection pump
MAPmanifold absolute pressure sensor
MILmalfunction indicator lamp
MTVmanifold tuning valve
O2Soxygen sensor
PCIprogrammable communication inter-
face
PCMpowertrain control module
PCVpositive crankcase ventilation
PEPperipheral expansion port
poor fuel
economyThere is significantly less fuel mile-
age than other vehicles of the same
design ad configuration
12
GENERAL INFORMATION
rough,
unstable,
or er-
ratic idle
stallingThe engine runs unevenly at idle
and causes the engine to shake if it
is severe enough. The engine idle
rpm may vary (called hunting). This
condition may cause stalling if it is
severe enough.
SBECsingle board engine controller
SKIMsentry key immobilizer module
SKISsentry key immobilizer systemstart &
stallThe engine starts but immediately
dies.
surgeengine rpm fluctuation without cor-
responding change in throttle posi-
tion sensor
TPSthrottle position sensor
TRStransmission range sensor
VSSvehicle speed sensor/signal
13
GENERAL INFORMATION
Symptom:
P0071 - AMBIENT TEMP SENSOR PERFORMANCE
When Monitored and Set Condition:
P0071 - AMBIENT TEMP SENSOR PERFORMANCE
When Monitored: With the ignition on. Coolant Temperature greater than 71ÉC (160ÉF)
No Inlet Air Temperature Sensor Faults present
Set Condition: After 5 warm cycles have occurred (coolant increases from great than
4.4ÉC (40ÉF) to a minimum of 71ÉC (160ÉF) and the odometer mileage has increased 196.6
miles and the Inlet Air Temperature has increased less than 3ÉC (5.4ÉF) change in
temperature. Two trip fault.
POSSIBLE CAUSES
INTERMITTENT CONDITION
IAT SENSOR VOLTAGE BELOW 1.0 VOLTS
SENSOR GROUND CIRCUIT VOLTAGE DROP
IAT SENSOR SIGNAL CIRCUIT VOLTAGE DROP
PCM
TEST ACTION APPLICABILITY
1NOTE: If DTC P1192 or P1193 have set along with P0071, diagnose P1192 or
P1193 first before continuing.
Turn the ignition on.
With the DRBIIIt, read DTC's.
Is the Good Trip displayed and equal to zero?All
Ye s®Go To 2
No®Go To 7
2 Turn the ignition off.
Disconnect the Inlet Air Temperature Sensor harness connector.
Turn the ignition on.
With the DRBIIIt, read the IAT voltage.
Is the voltage above 4.6 volts?All
Ye s®Go To 3
No®Go To 4
3 Turn the ignition off.
Disconnect the Inlet Air Temperature Sensor harness connector.
Using a jumper wire, jumper across the IAT Sensor harness connector.
Turn the ignition on.
With the DRBIIIt, read the IAT voltage.
Is the voltage below 1.0 volt?All
Ye s®Replace the Inlet Air Temperature Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No®Go To 4
43
DRIVEABILITY - GAS
TEST ACTION APPLICABILITY
4NOTE: Ensure the voltmeter leads meet the terminals in the connector and
that there is good terminal to wire connection.
NOTE: Ensure the voltmeter leads are connected for positive polarity
Backprobe between the Sensor ground circuit at the IAT Sensor harness connector
and PCM harness connector.
Start the engine.
Allow the engine to idle.
Is the voltage below 0.10 volt?All
Ye s®Go To 5
No®Repair the high resistance in the Sensor ground circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
5NOTE: Ensure the voltmeter leads meet the terminals in the connector and
that there is good terminal to wire connection.
NOTE: Ensure the voltmeter leads are connected for positive polarity
Backprobe between the IAT Sensor Signal circuit at the IAT Sensor harness
connector and PCM harness connector.
Start the engine.
Allow the engine to idle.
Is the voltage below 0.10 volt?All
Ye s®Go To 6
No®Repair the high resistance in the IAT Sensor Signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
6 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Powertrain Control Module in accor-
dance with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
7WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DRB Freeze Frame information to identify under what conditions the
DTC set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?All
Ye s®Repair as necessary
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No®Test Complete.
44
DRIVEABILITY - GAS
P0071 - AMBIENT TEMP SENSOR PERFORMANCE ÐContinued
Symptom:
P0106-BAROMETRIC PRESSURE OUT OF RANGE
When Monitored and Set Condition:
P0106-BAROMETRIC PRESSURE OUT OF RANGE
When Monitored: With the ignition key on. Engine speed at less than 250 RPM.
Set Condition: The PCM senses the voltage from the MAP sensor to be less than 2.196
volts but above 0.0392 volts for 300 milliseconds.
POSSIBLE CAUSES
INTERMITTENT CONDITION
5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
5 VOLT SUPPLY CIRCUIT SHORTED TO GROUND
5 VOLT SUPPLY CIRCUIT OPEN
MAP SENSOR INTERNAL FAILURE
MAP SENSOR SIGNAL CIRCUIT OPEN
MAP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
PCM 5 VOLT SUPPLY CIRCUIT
PCM MAP SENSOR SIGNAL
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, read the MAP Sensor voltage.
Is the voltage below 2.2 volts.All
Ye s®Go To 2
No®Go To 11
2 Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Turn the ignition on.
Measure the voltage of the 5 Volt Supply circuit in the MAP Sensor harness
connector.
Is the voltage between 4.5 to 5.2 volts?All
Ye s®Go To 3
No®Go To 7
45
DRIVEABILITY - GAS
TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Turn the ignition on.
With the DRBIIIt, monitor the MAP Sensor voltage.
Is the voltage above 2.2 volts?All
Ye s®Replace the MAP Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No®Go To 4
4 Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Disconnect the PCM harness connector.
Measure the resistance of the MAP Sensor Signal circuit between the MAP Sensor
harness connector and the PCM harness connector.
Is the resistance below 5 ohms?All
Ye s®Go To 5
No®Repair the MAP Sensor Signal circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
5 Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Disconnect the PCM harness connector.
Measure the resistance of the MAP Sensor Signal circuit in the MAP Sensor harness
connector to ground.
Is the resistance below 100 ohms?All
Ye s®Repair the MAP Sensor Signal circuit for a short to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No®Go To 6
6 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Powertrain Control Module in accor-
dance with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
7 Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Turn the ignition on.
Measure the voltage of the 5 Volt Supply circuit in the MAP Sensor harness
connector.
Is the voltage above 5.2 volts?All
Ye s®Repair the 5 Volt Supply circuit for a short to voltage.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No®Go To 8
46
DRIVEABILITY - GAS
P0106-BAROMETRIC PRESSURE OUT OF RANGE ÐContinued
TEST ACTION APPLICABILITY
8 Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Disconnect the PCM harness connector.
Measure the resistance of the 5 Volt Supply circuit in the MAP Sensor harness
connector to ground.
Is the resistance below 100 ohms?All
Ye s®Repair the 5 Volt Supply circuit for a short to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No®Go To 9
9 Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Disconnect the PCM harness connector.
Measure the resistance of the 5 Volt Supply circuit between the MAP Sensor harness
connector and the PCM harness connector.
Is the resistance below 5 ohms?All
Ye s®Go To 10
No®Repair the 5 Volt Supply circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
10 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Powertrain Control Module in accor-
dance with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
11WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DRB Freeze Frame information. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?All
Ye s®Repair as necessary
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No®Test Complete.
47
DRIVEABILITY - GAS
P0106-BAROMETRIC PRESSURE OUT OF RANGE ÐContinued