Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL KL]
STEP
INSPECTION ACTION
8 CHECK CDCV RESISTANCE
• Key off.
• Disconnect CDCV vehicle harness
connector.
• Measure resistance between CDCV
teminals.
• Is resistance less than 45 ohms?
Yes
CDCV Is shorted to ground in CDCV.
REPLACE CDCV.
RECONNECT all components.
RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No Go to next step.
9 CHECK CDCV SIGNAL CIRCUIT FOR
SHORT TO GROUND CIRCUIT
• Key off.
• CDCV disconnected.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion and loose wires.
Service as necessary.
• Install breakout box. Leave PCM
disconnected.
• Disconnect NGS tester from DLC.
• Measure resistance between Test Pin
1 8
and Test Pins 51 and 103 at breakout box.
• Is each resistance greater than 10,000
ohms?
Yes Go to next step.
No
SERVICE harness short between CDCV and ground
circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
10 INSPECTION OF FUEL TANK
• Remove and Inspect fuel tank.
• Is fault detected?
Yes SERVICE or REPLACE fuel tank or sealing.
RECONNECT all components.
RESET PCM to completely clear DTCs.
d
- After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No UNABLE to duplicate or identify fault at time.
Go to ENGINE SYMPTOM TROUBLESHOOTING No.30.
DTC P0452 Evaporative emission control system fuel tank pressure sensor circuit low input
DESCRIPTION
• Diagnostic trouble code P0452 Indicates that Fuel Tank Pressure (FTP) sensor input signal
is below minimum.
[Possible Cause]
• FTP sensor completely submerged in liquid fuel • FTP sensor ground short circuit
• Inside contamination of FTP sensor connector • Damaged FTP sensor
• Ground circuit short circuit • Damaged PCM
STEP
INSPECTION ACTION
1 CHECK FOR FUEL SATURATION OF FTP
SENSOR
• Key off.
• Visually check for liquid fuel contamination
of FTP sensor electrical connector.
• Check for completely submerged FTP
sensor in liquid fuel (can affect correct FTP
voltage reading).
• Does FTP sensor and/or connector
show signs of fuel contamination?
Yes SERVICE FTP sensor electrical connector as necessary.
If FTP sensor is completely submerged In fuel, DRAIN fuel
tank and REFILL to proper fuel level.
RESET PCM to completely clear DTCs.
o ’ After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No INSTALL original FTP sensor in fuel tank.
Go to step 6 and RETURN to Pinpoint Test Step that
directed you here.
Go to next step.
2 VERIFY FTP SIGNAL VOLTAGE
• Key on, engine off.
Note
• FTP sensor input with no pressure/vacuum
on fuel tank (filler cap open or not open to
atmosphere) is 2.37— 2.87 volts. Access
FTP V PID with NGS tester.
• Is FTP V PID voltage less than 0.22 volt?
Yes FTP sensor voltage less than acceptable minimum.
Go to next step.
No Fault that produced DTC P0452 is intermittent.
Perform Wiggle/Tap test.
01-01B-72