Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION
ACTION
6 Start engine and run it at idle speed.
Turn A/C switch on.
Do condenser fan and main cooling fan
operate?
Yes Go to next step.
No If condenser fan does not operate, check following:
Condenser fan relay stuck to open.
Condenser fan motor malfunction.
Condenser fan motor ground open.
Open circuit between condenser fan motor and relay.
Open circuit between condenser fan relay and PCM.
Open battery power circuit for condenser fan relay.
If cooling fan motor does not operate, check
following:
Cooling fan relay stuck to open.
Cooling fan motor malfunction.
Cooling fan motor ground open.
Open circuit between cooling fan motor and relay.
Open circuit between cooling fan relay and PCM.
Open battery power circuit for cooing fan relay.
7
Is drive belt okay? Yes Go to next step.
No Replace drive belt.
8 Are there any leaks around heater unit in
passenger compartment? Yes
Check and service heater unit for leaks.
No Go to next step.
9 Are there any leaks at coolant hoses and/or
radiator?
Yes
Replace malfunctioning part.
No Inspect engine block for leaks or blockage.
10 Verify test results. If okay, return to diagnostic index to service any additional symptoms.
18 COOLING SYSTEM CONCERNS RUNS COLD
DESCRIPTION Engine takes excessive period for reaching normal operating temperature
POSSIBLE
CAUSE
• Thermostat malfunction
• Malfunction of cooling fan system
• Malfunction of condenser fan system
STEP INSPECTION ACTION
1 Is custom er’s any complaint “Lack of
passenger compartment heat”? Yes Check A/C and heater system.
No Go to next step.
2 Does engine speed continue at fast idle? Yes Go to flowchart 8 for “FAST IDLE/RUNS ON” .
No Go to next step.
3 Connect NGS tester to data link connector.
Access ECT V PID.
Start engine and record ECT signal voltage
reading every 60 seconds.
Note
• When ECT signal voltage reverses
direction trend or changes slightly (0.03 volt
or less), thermostat has opened.
Is thermostat opening voltage okay?
Thermostat opening voltage
Approx. 0.6— 0.9 V
Yes Check condenser fan and cooling fan operation.
If both or either fan operate abnormally, check follows:
• Cooling fan relay stuck to close.
• Condenser fan relay stuck to close.
• Short to ground between cooling fan relay and PCM.
• Short to ground between condenser fan relay and
PCM.
• Circuit between cooling fan relay and fan motor shorts
to battery supply line.
• Circuit between condenser fan relay and fan motor
shorts to battery supply line.
No
Remove thermostat from engine and verify thermostat
operation.
If temperature gauge on instrument cluster indicates
normal range but ECT V is not same as temperature
gauge reading, check ECT sensor.
If temperature gauge on instrument cluster indicates cold
range but ECT signal voltage is normal, check
temperature gauge and heat gauge unit.
4 Verify test results. If okay, return to diagnostic index to service any additional symptoms.
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