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
Certain criteria must be met for a diagnostic
trouble code to be entered into the SKIM memeory.
The criteria may be a range of; Input voltage, CCD
Bus message, or coded messages to the SKIM. If all
of the criteria for monitoring a circuit or function
are met and a fault is sensed, a diagnostic trouble
code will be stored in the SKIM memory.
3.2.8 SKIS OPERATION
When ignition power is supplied to the SKIM, the
SKIM performs an internal self-test. After the self-
test is completed, the SKIM neergizes the antenna
(this activates the transponder chop responds to the
challenge by generating an encrypted response
message using the following:
Secret Key -This is an electronically stored
value (identification number) that is unique to each
SKIS. The secret key is stored in the SKIM, PCM
and all ignition key tranponders.
Challenge -This is a random numbr that is
generated by the SKIM at each ignition key cycle.
The secret key and challenge are plugged into an
algorithm that produces the encrypted response
message. The transponder uses the crypto algo-
rithm to receive, decode and respond to the message
sent by the SKIM. After responding to the coded
message, the transponder sends a transponder ID
message to the SKIM. The SKIM compares the
transponder ID to the available valid key codes in
the SKIM memory (8 key maximum). After validat-
ing the key the SKIM sends a CCD Bus message
called a ``Seed Request'' to the engine controller
then waits for a PCM response. If the PCM does not
respond, the SKIM will send the seed request agian.
After three failed attempts the SKIM will stop
sending the seed request and store a trouble code. If
the PCM sends a seed response, the SKIM sends a
valid/invalid key message to the PCM. This is an
encrypted message that is generated using the
following:
VIN -Vehicle Identification Number
Seed -This is a random number that is generated
by the PCM at each ignition key cycle.
The VIN and seed are plugged into a rolling code
algorithm that encrypts the ``valid/invalid key'' mes-
sage. The PCM uses the rolling code algorithm to
receive, decode and respond to the valid/invalid key
message sent by the SKIM. After sending the valid/
invalid key massage the SKIM waits 3.5 seconds for
a PCM status message from the PCM. If the PCM
does not respond with a valid key message to the
SKIM, a fault is detected and a trouble code is
stored.
The SKIS incorporates a warning lamp (``ALARM
SET'') located in the message center. The lamp
receives switched ignition voltage and is hardwired
to the body control module. The lamp is actuated
when the SKIM sends a CCD Bus message to thebody controller requesting the lamp on. The body
controller then provides the ground for the lamp.
The SKIM will request lamp operation for the
following:
- bulb checks at ignition on
- to alert the vehicle operator to a SKIS malfunc-
tion
For all faults except transponder faults and VIN
mismatch, the lamp remains on steady. In the event
of a tranponder fault the light flashes at a rate of 1
Hz (once per second). If a fault is pesent the lamp
will emain on or flashing for the complete ignition
cycle. If a fault is stored in SKIM memory which
prevents the system form operating properly, the
PCM will allow the engine to start and run (for 2
seconds) up to six times. After the sixth attempt, the
PCM disables the starter relay until the fault is
corrected.
3.2.9 PROGRAMMING THE POWERTRAIN
CONTROL MODULE
Important Note:Before replacing the PCM for a
failed driver, control circuit or ground circuit, be
sure to check the related component/circuit integ-
rity for failures not detected due to a double fault in
the circuit. Most PCM driver/control circuit failures
are caused by internal failure to components (i.e.
12-volt pull-ups, drivers and ground sensors). These
failures are difficult to detect when a double fault
has occurred and only one DTC has set.
NOTE:IF THE PCM AND THE SKIM ARE
REPLACED AT THE SAME TIME, PROGRAM
THE VIN INTO THE PCM FIRST. ALL VEHICLE
KEYS WILL THEN NEED TO BE REPLACED
AND PROGRAMMED TO THE NEW SKIM.
The SKIS ``Secret Key'' is an ID code that is
unique to each SKIS. This code is programmed and
stored in the SKIM, engine controller and transpon-
der ship (ignition key). When replacing the PCM it
is necessary to program the secret key into the
PCM.
1. Turn the ignition on (transmission in park/
neutral).
2. Use the DRB and select ``THEFT ALARM'',
SKIM then MISCELLANEOUS''.
3. Select ``PCM REPLACED''.
4. Enter secured access mode by entering the vehi-
cle four-digit PIN.
6
GENERAL INFORMATION
ProCarManuals.com
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
applicable. These procedures can be found in ser-
vice manual procedures. Following these proce-
dures is very important to the safety of individuals
performing diagnostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If it does not, false diagnostic codes
or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the powertrain system are
intended to be serviced in assembly only. Attempt-
ing to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRB MULTIMETER IS DANGEROUS. IT CAN
EXPOSE YOU TO SERIOUS INJURY.
CAREFULLY READ AND UNDERSTAND THE
CAUTIONS AND THE SPECIFICATION
LIMITS.
Follow the vehicle manufacturer 's service specifi-
cations at all times.
²Do not use the DRBIIItif it has been damaged.
²Do not use the test leads if the insulation is
damaged or if metal is exposed.
²To avoid electrical shock, do not touch the test
leads, tips or the circuit being tested.
²Choose the proper range and function for the
measurement. Do not try voltage or current mea-
surements that may exceed the rated capacity.
²Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts 0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)* 0 -1.12 megohms
Frequency Measured
Frequency Generated0-10kHz
Temperature -58 - 1100ÉF
-50 - 600ÉC
* Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
²Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.
²Use caution when measuring voltage above 25v
DC or 25v AC.
²The circuit being tested must be protected by a
10A fuse or circuit breaker.
²Use the low current shunt to measure circuits up
to 10A. Use the high current clamp to measure
circuits exceeding 10A.
²When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.
²When measuring current, connect the meter in
series with the load.
²Disconnect the live test lead before disconnecting
the common test lead.
²When using the meter function, keep the DRB
away from spark plug or coil wires to avoid
measuring error from outside interference.
4.3 WARNINGS AND CAUTIONS
4.3.1 ROAD TEST WARNINGS
Some complaints will require a test drive as part
of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
code or symptom condition.
CAUTION: BEFORE ROAD TESTING A
VEHICLE, BE SURE THAT ALL
COMPONENTS ARE REASSEMBLED.
DURING THE TEST DRIVE, DO NOT TRY TO
READ THE DRB SCREEN WHILE IN MOTION.
DO NOT HANG THE DRB FROM THE REAR
VIEW MIRROR OR OPERATE IT YOURSELF.
HAVE AN ASSISTANT AVAILABLE TO
OPERATE THE DRB.
4.3.2 VEHICLE DAMAGE CAUTIONS
Before disconnecting any control module, make
sure the ignition is ªoffº. Failure to do so could
damage the module.
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 code could be set, making diagnosis of the
original problem more difficult.
12
GENERAL INFORMATION
ProCarManuals.com
4.3.3 ELECTRONIC PINION FACTOR
WARNING
The pinion factor must be set for all new trans-
mission control modules. If the pinion factor is not
set or if it is set incorrectly, any speed-related
accessories will not operate or will operate inaccu-
rately. This includes the speedometer, speed con-
trol, rolling door locks, and other devices that are
operated by the powertrain and body control mod-
ules. For instructions on setting the pinion factor,
see the appropriate transmission diagnostic man-
ual or the service manual.
5.0 RECOMMENDED TOOLS
AND EQUIPMENT
DRBIIIt(diagnostic readout box) scan tool
fuel pressure adapter (C-6631) or #6539
fuel pressure kit (C-4799-B) or #5069
fuel release hose (C-4799-1)
MinAir flow fitting #6457
jumper wires
ohmmeter
oscilloscope
vacuum gauge
voltmeter
12 volt test light minimum 25 ohms resistance
with probe #8382
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
ABSantilock brake system
backfire,
popbackfuel ignites in either the intake or
the exhaust system
CKPcrank position sensor
CMPcamshaft position sensor
cuts out,
missesa steady pulsation or the inability of
the engine to maintain a consistent
rpmDLCdata link connector (previously
called ªengine diagnostic connectorº)
detona-
tion,
spark
knocka mild to severe ping, especially un-
der loaded engine conditions
ECTengine coolant temperature sensor
EGRexhaust gas recirculation valve and
system
genera-
torpreviously called ªalternatorº
hard
startThe engine takes longer than usual
to start, even though it is able to
crank normally.
hesita-
tion, sag,
stumble
There is a momentary lack of response
when the throttle is opened.
This can
occur at all vehicle speeds. If it is se-
vere enough, the engine may stall.
IATintake air temperature sensor
IACidle air control valve
JTECCombined engine and transmission
control module
lack of
power,
sluggish
The engine has less than expected
power, with little or no increase in vehi-
cle speed when the throttle is opened.
LDPLeak Detection Pump
MAPmanifold absolute pressure sensor
MILmalfunction indicator lamp
MTVmanifold tuning valve
O2Soxygen sensor
PCIProgrammable Communication In-
terface
PCMpowertrain control module
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 and configuration
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 ªhuntingº).
This condition may cause stalling if
it is severe enough.
SKIMSentry Key Immobilizer Module
SKISSentry Key Immobilizer System
start and
stallThe engine starts but immediately
dies.
13
GENERAL INFORMATION
ProCarManuals.com
TEST ACTION APPLICABILITY
7 Turn ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Remove the pressure test port cap at the fuel rail test port. Connect a fuel pressure
gauge to the test port pressure fitting on the fuel rail.
Ignition on. With the DRB, actuate the ASD Fuel System test and observe the fuel
pressure gauge.
Note: Fuel pressure specification is 49.2 psi +/- 5 psi
Choose a conclusion that best matches your fuel pressure reading.All
Below Specification
Go To 8
Within Specification
Go To 11
Above Specification
Replace the fuel filter pressure regulator.
Caution: Stop ALL Actuations.
8 Turn ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Raise vehicle on hoist,and disconnect the fuel pressure line at the fuel pump module.
Install speial 5/169fuel line adapter tool #6539 between disconnected fuel line and
the fuel pump module.
Attach a fuel pressure test gauge to the88T'' fitting on tool #6539.
Ignition on. With the DRB, actuate the ASD Fuel System test and observe the fuel
pressure gauge.
Note: Fuel pressure specification is 49.2 psi +/- 5 psi.
Is the fuel pressure within specification now?ALL
Ye s®Repair the restriction in the chassis fuel supply line between the
fuel tank and fuel rail.
No®Go to 9
Caution: Stop ALL Actuations.
9Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.
Is the Fuel Inlet Strainer plugged?All
Ye s®Replace the Fuel Inlet Strainer.
No®Go To 10
10 If there are no potential causes remaining, the Fuel Pump Module is assumed to be
defective.
View repair options.All
Repair
Replace the Fuel Pump Module
77
DRIVEABILITY
P-0171±1/1 FUEL SYSTEM LEAN ÐContinued
ProCarManuals.com
TEST ACTION APPLICABILITY
11 Check for any of the following conditions/mechanical problems.
ENGINE VACUUM Ð must be at least 13 inches in neutral
ENGINE VALVE TIMING Ð must be within specifications
ENGINE COMPRESSION Ð must be within specifications
ENGINE EXHAUST SYSTEM Ð must be free of any restrictions or leaks
ENGINE PVC SYSTEM Ð must flow freely
TORQUE CONVERTER STALL SPEED Ð must be within specifications
POWER BRAKE BOOSTER Ð no internal vacuum leaks
FUEL- must be free of contamination
FUEL INJECTOR Ð plugged or restricted injector; control wire not connected to
correct injector.
Are there any engine mechanical problems?All
Ye s®Repair as necessary.
Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION
TEST
No®Go To 12
12 Turn ignition off.
Warning: The fuel system is under constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Disconnect the fuel supply line at the fuel rail.
Connect fuel line adapter #6539(5/169) or #6631 (3/89) to the disconnected fuel supply
line. Insert the other end of the adapter into a graduated container.
Caution: Do not operate the fuel pump for more than 7 seconds in the next
step. Fuel pump module reservoir may run empty and damage to the fuel
pump may result.
Specification: A good fuel pump will deliver at least 1/4 liter of fuel in 7
seconds.
With the DRB, actuate the ASD Fuel System test for 7 seconds.
Is the fuel pump capacity within specification?All
Ye s®Test Complete.
No®Check for a kinked/damaged fuel supply line between the fuel
tank and fuel rail. If OK, replace the fuel filter/pressure regulator.
Caution: Stop ALL Actuations.
13 The conditions required to set the DTC are no longer present.
With the DRB read and record the freeze frame data and the ªFuel System Similar
Conditions Windowº data.
Utilize the data and try to duplicate the operating conditions at which the DTC was
set. Pay particular attention to the ECT and RPM for added diagnostics.
Note: Refer to any TSB's that may apply to the symptom.
Test Complete
Repair
Test Complete.
78
DRIVEABILITY
P-0171±1/1 FUEL SYSTEM LEAN ÐContinued
ProCarManuals.com
TEST ACTION APPLICABILITY
8 Turn ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Remove the pressure test port cap at the fuel rail test port. Connect a fuel pressure
gauge to the test port pressure fitting on the fuel rail.
Ignition on. With the DRB, actuate the ASD Fuel System test and observe the fuel
pressure gauge.
Note: Fuel pressure specification is 49.2 psi +/þ 5 psi.
Choose a conclusion that best matches your fuel pressure reading.All
Below Specification
Go To 9
Within Specification
Go To 13
Above Specification
Replace the fuel filter/pressure regulator.
Caution: Stop ALL Actuations.
9 Check for any of the following conditions/mechanical problems.
ENGINE VACUUM Ð must be at least 13 inches in neutral
ENGINE VALVE TIMING Ð must be within specifications
ENGINE COMPRESSION Ð must be within specifications
ENGINE EXHAUST SYSTEM Ð must be free of any restrictions or leaks.
ENGINE PVC SYSTEM Ð must flow freely
TORQUE CONVERTER STALL SPEED Ð must be within specifications
POWER BRAKE BOOSTER Ð no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR Ð plugged or restricted injector; control wire not connected to
correct injector
Are there any engine mechanical problems?All
Ye s®Repair as necessary.
Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION
TEST
No®Go To 10
10 Turn ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.
Install special 5/169fuel line adapter tool #6539 between disconnected fuel line and
the fuel pump module.
Attach a fuel pressure test gauge to the ªT'' fitting on tool #6539.
Ignition on. With the DRB, actuate the ASD Fuel System test and observe the fuel
pressure gauge.
Note: Fuel pressure specification is 49.2 psi +/- 5 psi.
Is the fuel pressure within specification now?All
Ye s®Repair the restriction in the chassis fuel supply line between the
fuel tank and fuel rail.
No®Go to 11
Caution: Stop ALL Actuations.
81
P0172 -1/1 FUEL SYSTEM RICH ÐContinued
ProCarManuals.com