The PCM determines the spark advance based on
the following:
± engine coolant temperature
± crankshaft position
± camshaft position
± intake air temperature
± manifold absolute pressure
± throttle position
Engine Warm-Up Mode -This is an open loop-
mode. The PCM adjusts injector pulse width and
controls injector synchronization by controlling the
fuel injectors' ground paths. The PCM adjusts igni-
tion timing and engine idle speed. The PCM adjusts
the idle speed by controlling the idle air control
motor and spark advance.
Cruise or Idle Mode -When the engine is at
normal operating temperature, this is a closed loop
mode.
Acceleration Mode -This is a closed loop mode.
The PCM recognizes an increase in throttle position
and a decrease in manifold vacuum as engine load
increases. In response, the PCM increases the in-
jector pulse width to meet the increased load. The
A/C compressor may be de-energized for a short
period of time.
Deceleration -This is a closed loop mode. The
PCM recognizes a decrease in throttle position and
an increase in manifold vacuum as engine load
decreases. In response, the PCM decreases the
injector pulse width to meet the decreased load.
Full injector shut off may be obtained during high
speed deceleration.
Wide Open Throttle Mode -This is an open
loop mode. The throttle position sensor notifies the
PCM of a wide open throttle condition. Once a wide
open throttle is sensed, the PCM de-energizes the
A/C compressor clutch relay for 15 seconds.
3.2.5 NON-MONITORED CIRCUITS
The PCM does not monitor the following circuits,
systems, and conditions even though they could
have malfunctions that result in driveability prob-
lems. A diagnostic code may not be displayed for the
following conditions. However, problems with these
systems may cause a diagnostic code to be displayed
for other systems. For example, a fuel pressure
problem will not register a diagnostic code directly,
but could cause a rich or lean condition. This could
cause an oxygen sensor, fuel system, or misfire
monitor trouble code to be stored in the PCM.
Engine Timing -The PCM cannot detect an
incorrectly indexed timing chain, camshaft
sprocket, or crankshaft sprocket. The PCM also
cannot detect an incorrectly indexed distributor.(*)
Fuel Pressure -Fuel pressure is controlled by
the fuel pressure regulator. The PCM cannot detecta clogged fuel pump inlet filter, clogged in-line filter,
or a pinched fuel supply.(*)
Fuel Injectors -The PCM cannot detect if a fuel
injector is clogged, the pintle is sticking, or the
wrong injectors are installed.(*)
Fuel Requirements -Poor quality gasoline can
cause problems such as hard starting, stalling, and
stumble. Use of methanol-gasoline blends may re-
sult in starting and driveability problems. See indi-
vidual symptoms and their definitions in Section
6.0 (Glossary of Terms)
PCM Grounds -The PCM cannot detect a poor
system ground. However, a diagnostic trouble code
may be stored in the PCM as a result of this
condition.
Throttle Body Air Flow -The PCM cannot
detect a clogged or restricted air cleaner inlet or
filter element.(*)
Exhaust System -The PCM cannot detect a
plugged, restricted, or leaking exhaust system.(*)
Cylinder Compression -The PCM cannot de-
tect uneven, low, or high engine cylinder compres-
sion.(*)
Excessive Oil Consumption -Although the
PCM monitors the exhaust stream oxygen content
through the oxygen sensor when the system is in a
closed loop, it cannot determine excessive oil con-
sumption.
(*)NOTE: ANY OF THESE CONDITIONS
COULD RESULT IN A RICH OR LEAN
CONDITION CAUSING AN OXYGEN SENSOR
TROUBLE CODE TO BE STORED IN THE
PCM, OR THE VEHICLE MAY EXHIBIT ONE
OR MORE OF THE DRIVEABILITY
SYMPTOMS LISTED IN THE TABLE OF
CONTENTS.
3.2.6 SKIS OVERVIEW
The Sentry Key Immobilizer System (SKIS) is an
immobilizer system design to prevent unauthorized
vehicle operation. The system consists of a Sentry
Key Immobilizer Module (SKIM), ignition key(s)
equipped with a transponder chip and engine con-
troller. When the ignition switch is turned on, the
SKIM interrogates the ignition key. If the ignition
key is ``Valid'', the SKIM sends a CCD Bus message
to the engine controller indicating the presence of a
valid igntion key. Upon receiving a ``Valid'' key
signal the PCM will allow the engine to continue to
operate.
3.2.7 SKIM ON-BOARD DIAGNOSTICS
The SKIM has been programmed to transmit and
monitor many different coded messages as well as
CCD Bus messages. This monitoring is called ``On
Board Diagnosis''.
5
GENERAL INFORMATION
ProCarManuals.com
Verification Tests
VERIFICATION TEST VER-1A APPLICABILITY
No Start Verification
Use this test to verify that a No Start condition has been repaired and that the vehicle can be
returned to the customer.
Note: If the Powertrain Control Module has been replaced and the correct VIN and
mileage have not been programmed, a DTC will be set in the ABS, Airbag and the
SKIM modules. In addition, if the vehicle is equipped with a Sentry Key Immobilizer
Module (SKIM), Secret Key data must be updated to enable starting. Refer to
GENERAL INFORMATION section for programming information for the PCM, SKIM
and the Transponder (ignition key).
1. Inspect the vehicle to ensure that all components related to the repair are connected
properly.
2. Inspect the engine oil for fuel contamination. Replace the oil and filter as necessary
3. Attempt to start the engine.
4. If the No Start condition is still present, refer to the symptom list and perform diagnostic
testing as necessary. Refer to any Technical Service Bulletins that may apply.
5. Run the engine for one warm-up cycle to verify proper operation. With the DRBIIIt, confirm
that no DTC's are present and that all components are functioning properly.
6. If DTC's are present, refer to the symptom list and perform diagnostic testing as necessary.ALL
VERIFICATION TEST VER-2A APPLICABILITY
Non-OBDII Verification
Use this test to verify that a non-OBDII symptom has been repaired and that the vehicle can
be returned to the customer. A non-OBDII symptom is a comprehensive component related
symptom that is not the result of a failed OBDII major monitor.
Note: If the Powertrain Control Module has been replaced and the correct VIN and
mileage have not been programmed, a DTC will be set in the ABS, Airbag and the
SKIM modules. In addition, if the vehicle is equipped with a Sentry Key Immobilizer
Module (SKIM), Secret Key data must be updated to enable starting. Refer to
GENERAL INFORMATION section for programming information for the PCM, SKIM
and the Transponder (ignition key).
1. Inspect the vehicle to ensure that all components related to the repair are connected
properly.
2. With the DRBIIIt, Clear DTC's and Reset Memory (all engine values).
3. Run the engine for one warm-up cycle to verify proper operation.
4. Road test the vehicle. Use all accessories that may be related to this repair.
With the DRBIIIt, confirm that no DTC's are present and that all components are functioning
properly.
6. If this test is being performed after a No Trouble Code test, verify that the symptom is no
longer present. If the symptom is still present, or any other symptom or DTC is present, refer
to the symptom list for further diagnostic testing procedures. Check for any Technical Service
Bulletins that may apply.
7. If there are no DTC's present and all components are functioning properly, repair is
complete.ALL
317
VERIFICATION TESTS
ProCarManuals.com
Powertrain Verification Test VER-7A APPLICABILITY
SKIS Verfication
Use this test to verify that SKIM system symptom has been repaired and that the vehicle can
be returned to the customer.
Note: If the Powertrain Control Module has been replaced and the correct VIN and
mileage have not been programmed, a DTC will be set in the ABS, Airbag and SKIM
modules. In addition, if the vehicle is equipped with a Sentry Key Immobilizer
Module (SKIM), Secret Key data must be updated to enable starting. Refer to
GENERAL INFORMATION section for programmig information for the PCM, SKIM
and the Transponder (ignition key).
1.Inspect the vehicle to ensure that all components related to the repair are connected properly.
2. Inspect the engine oil for fuel contamination. Replace the oil and filter as necessary.
3. Start the engine.
4. Run the engine for one warm-up cycle to verify proper operation. With the DRBIIIt, confirm
that no DTCs are present and that all components are functioning properly. If the DTC is still
present refer to any Technical Service Bulletins that may apply.
5. If a different DTC(s) is present, refer to the symtom list and perform diagnostic testing as
necessary. If there are no DTCs present and all components are functioning correctly, repair is
now complete.All
322
VERIFICATION TESTS
Verification Tests ÐContinued
ProCarManuals.com