Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
27 INTERMITTENT CONCERNS
DESCRIPTION Symptom occurs randomly and is difficult to diagnose
STEP INSPECTION ACTION
1 Talk to customer and fill out “Check Sheet.”
Review vehicle service history.
Does vehicle have a number of previous
repairs and components replaced for a certain
symptom?
Yes Go to next step.
No Go to diagnostic chart for symptom.
2 Key on, engine off.
Connect NGS tester to DLC.
Access PIDs based on information from the
Symptom Charts.
Lightly tap on component while viewing PID
values. Wiggle and pull each component wire
(Signal, ground and constant voltage, if
applicable) at the component.
W iggle and pull each sensor wire (Signal,
ground and constant voltage, if applicable)
from the component back to PCM connector.
Look for abrupt changes in PID values.
Are any PID values out of range or suddenly
drop out and back into range?
Yes Possible wiring or component problem.
Check each wire for corrosion, bent or loose terminals and
poor wire terminal crimps.
Service as necessary.
Otherwise, replace component.
Verify repair.
No Go to next step.
3
Continue to monitor information from previous
step.
Key on, engine running.
Lightly tap on component while viewing PID
values.
Also wiggle and pull each component wire
(Signal, ground and constant voltage, if
applicable) from component back to PCM
connector.
Look for abrupt changes in PID values.
Are any PID values out of range or suddenly
drop out and back into range?
Yes Possible wiring or component problem.
Check each wire for corrosion, bent or loose terminals and
poor wire terminal crimps.
Service as necessary.
Otherwise, replace component.
Verify repair.
No Go to next step.
4 Continue to monitor PIDs listed in previous
step.
With engine still running, individually water
soak the wires and connectors related to the
monitor items.
Look for abrupt changes in PID values or
engine running conditions.
Are any PID values out of range or suddenly
drop out and back into range or was there
noticeable engine misfire/stumble? Yes
Fault area is identified. If fault occurred while spraying on
component, replace part and verify repair. If unable to
verify, reinstall original part. If fault occurred while spraying
the wiring, check each circuit wire for corrosion, bent or
loose terminals and poor wire terminal crimps.
Service as necessary.
If fault occurred while spraying the vacuum line.
Service as necessary.
Verify repair.
No Go to next step.
5 Continue to monitor information from previous
step.
Drive the vehicle under “Check Sheet”
condition.
Look for abrupt changes in PID values.
Are any PID values out of range or suddenly
drop out and back into range?
Yes Possible wiring or component problem.
Check each wire for corrosion, bent or loose terminals and
poor wire terminal crimps.
Service as necessary.
Otherwise, replace component.
Verify repair.
No Reconfirm “Check Sheet" and reselect related PIDs.
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