Chrysler PT Cruiser 2001 Service Manual Supplement page 2461

1.0 INTRODUCTION
The procedures contained in this manual include
specifications, instructions, and graphics needed to
diagnose the PCM Powertrain System. The diag-
nostics in this manual are based on the failure
condition or symptom being present at time of
diagnosis.
Please follow the recommendations below when
choosing your diagnostic path.
1. First make sure the DRBIII is communicating
with the appropriate modules; ie., if the DRBIII
displays No Response condition, you must diag-
nose this first before proceeding.
2. Read DTC's (diagnostic trouble codes) with the
DRBIII .
3. If no DTC's are present, identify the customer
complaint.
4. Once the DTC or customer complaint is identi-
fied, locate the matching test in the Table of
Contents and begin to diagnose the symptom.
All component location views are in Section 8.0.
All connector pinouts are in Section 9.0. All system
schematics are in Section 10.0.
An * placed before the symptom description indi-
cates a customer complaint.
When repairs are required, refer to the appropri-
ate service manual for the proper removal and
repair procedure.
Diagnostic procedures change every year. New
diagnostic systems may be added; carryover sys-
tems may be enhanced. READ THIS MANUAL
BEFORE TRYING TO DIAGNOSE A VEHICLE
CODE. It is recommended that you review the
entire manual to become familiar with all new and
changed diagnostic procedures.
After using this book, if you have any comments
or recommendations, please fill out the form at the
back of the book and mail it back to us.
1.1 SYSTEM COVERAGE
This diagnostic procedures manual covers the
2001 PT with the 2.0L and 2.4L engines.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the powertrain control module
(PCM) is done in six basic steps:
• verification of complaint
•
verification of any related symptoms
GENERAL INFORMATION
•
symptom analysis
•
problem isolation
• repair of isolated problem
• verification of proper operation
2.0 IDENTIFICATION OF
SYSTEM
The Powertrain Control Module (PCM) monitors
and controls:
•
Fuel System
•
Idle Air Control System
• Ignition System
• Charging System
•
Speed Control System
•
Cooling System
• 1/1 O2 Sensor Heater
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 GENERAL DESCRIPTION
These Sequential Fuel Injection (SFI) engine sys-
tems have the latest in technical advances. The
Euro Stage III On-Board Diagnostics incorporated
with the powertrain control module (PCM) are
intended to assist the field technician in repairing
vehicle problems by the quickest means.
3.2 FUNCTION OPERATION
3.2.1 FUEL CONTROL
The PCM controls the air/fuel ratio of the engine
by varying fuel injector on time. Mass air flow is
calculated using the speed density method using
engine speed, manifold absolute pressure, and air
temperature change.
Different fuel calculation strategies are used de-
pendent on the operational state of the engine.
During crank mode, a prime shot fuel pulse is
delivered followed by fuel pulses determined by a
crank time strategy. Cold engine operation is deter-
mined via an open loop strategy until the O2
sensors have reached operating temperature. At
this point, the strategy enters a closed loop mode
where fuel requirements are based upon the state of
the O2 sensors, engine speed, MAP, throttle posi-
tion, air temperature, battery voltage, and coolant
temperature.
1