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Home >> Mazda >> 2005 >> MX-5 Miata Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Symptom Troubleshooting [Engine Control System BP, BP With TC) >> No.27 Intermittent Concerns >> Diagnostic Procedure

Diagnostic Procedure

NO.27 INTERMITTENT CONCERNS [BP, BP WITH TC] DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1
  • Talk to customer.
  • Review vehicle service history.
  • Does vehicle have a number of previous repairs and components replaced for a certain symptom?
 Yes Go to the next step.
No Go to .
2
  • Turn ignition switch off.
    • If input is a switch-type component, turn on manually.
  • Turn ignition switch to ON.
  • Engine is off.
  • Measure PCM terminal voltages for suspect component.
  • Lightly tap on suspect component, wiggle and pull each wire/connector at suspect component or PCM.
  • Are any PCM terminal voltages out of range, or do they suddenly change and go back into range?
 Yes Inspect each wire for corrosion, bent or loose terminal crimps.
No Go to the next step.
3
  • Turn ignition switch to ON.
  • Engine is running.
  • Measure PCM terminal voltages for suspect component.
  • Lightly tap on suspect component, wiggle and pull each wire/connector at suspect component or PCM.
  • Are any PCM terminal voltages out of range, or do they suddenly change and go back into range?
 Yes Inspect each wire for corrosion, bent or loose terminal crimps.
No Go to the next step.
4
  • Turn ignition switch to ON.
  • Engine is running.
  • Measure PCM terminal voltages for suspect component.
  • Accurately spray water on suspect component wire, component or vacuum line related to possible fault area.
  • Are any PCM terminal voltages out of range, or suddenly change and go back into range, or was there a noticeable engine misfire/stumble?
 Yes Fault area is identified.
If fault occurred while spraying on component: 
Replace part and verify repair.
If fault occurred while spraying wiring: 
Inspect each wire for corrosion, bent or loose terminals and poor wire terminal crimps.
If fault occurred while spraying vacuum line: 
Repair vacuum hoses.
No Inspect wire and connector at suspect component for corrosion, bent or loose terminals, poor wire terminal crimps and high tension of wire.
  • Repair if necessary.
5
  • Verify test results.
    • If okay, return to diagnostic index to service any additional symptoms.
    • If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.
      • If vehicle is repaired, troubleshooting completed.
      • If vehicle is not repaired or additional diagnostic information is not available, replace PCM.
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