Mazda MX-6 1998, Workshop Manual

Page: 284 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION
ACTION
11 VERIFY FTP SIGNAL VOLTAGE
• Clamp on hose on tank side of charcoal
canister.
• Remove filler cap.
• Connect NGS tester.
• Key on, engine off.
• Access FTP V PID with NGS tester.
• Are FTP V PID values same as
atmospheric pressure (approx. 2.5 V)?
Yes Install filler cap.
Go to step 15.
No Install filler cap.
Go to next step.
12 INDUCE OPPOSITE FTP SIGNAL
• Key off.
• Disconnect FTP sensor vehicle harness
connector.
• Connect jumper at constant voltage circuit
between FTP sensor and sensor vehicle
harness connector.
• Key on, engine off.
• If NGS tester communication concern
Yes REPLACE damaged FTP sensor.
RECONNECT all components.
RESET PCM to completely clear DTCs.
o - After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
exists, remove jum per immediately and go
directly to next step.
• Access FTP V PID.
• Is FTP V PID value between 4.0 and 6.0
volts?
No REMOVE jumper.
Go to next step.
13 CHECK VREF AT FTP SENSOR VEHICLE
HARNESS CONNECTOR
• FTP sensor disconnected.
• Key on, engine off.
• Measure voltage between constant voltage
circuit and FTP sensor ground circuit at
FTP sensor vehicle harness connector.
• Is constant voltage between 4.0 and 6.0
volts?
Yes Go to next step.
No
Constant voltage is out of range.
SERVICE or REPLACE constant voltage circuit.
RECONNECT all components.
RESET PCM to completely clear DTCs.
o - After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
14 CHECK FTP SIGNAL CIRCUIT FOR
SHORTS TO FTP SENSOR GROUND AND
GROUND CIRCUIT
• Key off.
• Disconnect FTP sensor.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion and loose wires.
Sen/ice as necessary.
• Install breakout box. Leave PCM
Yes FTP is shorted to FTP sensor ground or ground circuit in
PCM.
REPLACE PCM.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
o - After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
disconnected.
• Disconnect NGS tester from DLC.
• Measure resistance between Test Pin
62
and Test Pin 91 at breakout box.
• Measure resistance between Test Pin 62
and Test Pins 51 and 103 at breakout box.
• Is each resistance greater than 10,000
ohms?
No
SERVICE harness short between FTP signal and FTP
sensor ground or ground circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
o= After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
15 CHECK FOR EVAPORATIVE EMISSION
MONITOR SYSTEM
• Key off.
• Disconnect vacuum hose from charcoal
canister at fuel tank side.
• Attach vacuum pump to vacuum hose.
• Connect NGS tester.
Yes DISCONNECT NGS tester.
Go to step 20.
• Key on, engine off.
• Access FTP V PID.
• Apply vacuum by using vacuum pump.
• Does FTP V PID values change on
negative pressure side?
V
01-40 FUEL TANK PRESSURE
SENSOR INSPECTION
No
DISCONNECT NGS tester.
Go to next step.
01-01B-78