Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
FOREWORD
Before proceeding with the following troubleshooting.
•
Refer to section 00-00 to understand the basic
troubleshooting procedure.
• Perform the diagnostic trouble code (DTC)
inspection.
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• If a DTC is displayed, proceed with the
appropriate inspection steps.
• After starting the engine, perform “ENGINE
TUNE-UP”.
ENGINE ON-BOARD DIAGNOSIS [FS]
On-Board Diagnostic (OBD) Test Description
OBD Test is divided into three special tests: Key On
Engine Off Self-Test, Key On Engine Running
Self-Test and Continuous Memory DTCs Self-Test.
The OBD Test checks the integrity and function of the
powertrain control system and outputs the test results
when requested by the NGS Tester. If also provides a
quick end check of the powertrain control system, is
usually performed at the start of each diagnostic
procedure with all accessories off and is performed at
end of most troubleshooting tests for verification of
repair and make sure no other faults were incurred
while servicing a previous fault.
System Pass
A system pass will be displayed when no DTCs are
output and no NGS Tester communication error
exists. System pass means that hardware monitored
by the PCM is functioning within normal operating
limits. When using the NGS Tester, all step by step
instructions are defined in the NGS instruction
manual. When using a generic scan tool, KOEO and
KOER self-tests may not be supported. Refer to the
manufacturer’s manual for details.
Key On Engine Off (KOEO) Self-Test
Key On Engine Off (KOEO) is a functional test of the
PCM performed on demand. A fault must be present
at the time of testing for the KOEO Self-Test to detect
the fault. This test will perform checks on certain
sensor and actuator circuits. A Diagnostic Trouble
Code (DTC) will be output on the data link at the end
of the test when requested by the NGS tester. Only
system pass, hard fault code or an incomplete OBD II
drive mode will be displayed.
Key On Engine Running (KOER) Self-Test
Key On Engine Running (KOER) is a functional test of
the PCM performed on demand with the engine
running and vehicle stopped. A check of the inputs
and outputs is made during operating conditions and
at normal temperature. The brake on/off, transaxle
control and power steering pressure switch tests are
part of the KOER self-test and MUST be performed
during this operation (see below). A fault must be
present at the time of testing to detect the fault. A
Diagnostic Trouble Code (DTC) will be output on the
data link at the end of the test when requested by the
NGS tester. Only system pass, hard fault code or an
incomplete OBD II drive mode will be displayed.
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Read/Clear Continuous Memory DTC Access
Self-Test
Continuous DTC access is also a functional test of the
powertrain control system. The continuous self-test is
always active. The test consists of all the OBD II
monitors and the comprehensive component monitor,
and is designed to detect failures contributing to
driveability and emission concerns. As part of an OBD
Test, the technician may perform a specific drive
mode before running the OBD Test. This is necessary
to detect certain faults not tested during other self-test
operations. All self-tests are menu driven in the NGS
tester.
Parameter Identification (PID) Access
The PID mode allows access to certain data values,
analog and digital inputs and outputs, calculated
values and system status information.
Brake On/Off Test
This tests ability of the powertrain control system to
detect a state of change in the stop light switch. The
brake pedal
MUST briefly be applied and released on
all vehicles with brake on/off input. This test is done
during the KOER self-test.
Transaxle Control Switch Test
This tests ability of the powertrain control system to '
detect a state of change in the O/D OFF switch. The
switch
MUST briefly be cycle on all vehicles with a
O/D OFF switch. This test is done during the KOER
self-test.
Power Steering Pressure (PSP) Switch Test
This tests the ability of the powertrain control system
to detect a change in power steering fluid pressure.
The steering wheel
MUST briefly be turned at least
1/4 of a revolution. This test is done during the KOER
self-test.
On-Board Diagnostic Test
New generation star (NGS) tester hook-up
procedure
Note
• Make sure key is off.
1. Insert the vehicle interface module and program
card into the SST (NGS tester) control unit.
01-01 A -2