Mazda MX-6 1998, Workshop Manual

Page: 41 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
STEP INSPECTION
ACTION
5 CHECK CONTINUITY OF MAF SIGNAL
CIRCUIT
• Key off.
• MAF sensor disconnected.
• Breakout box installed. PCM disconnected.
• Measure resistance between MAF circuit at
the MAF sensor vehicle harness connector
and Test Pin 88 at the breakout box.
• Is resistance less than 5.0 ohms?
Yes MAF signal circuit to PCM is okay.
Go to next step.
No SERVICE open in MAF signal circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
t r After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
6 CHECK GROUND CIRCUIT TO MAF
SENSOR
• Key off.
• MAF sensor disconnected.
• Breakout box installed.
• Key on, engine off.
• Measure voltage between power circuit
and ground circuit at MAF sensor vehicle
harness connector.
• Is voltage greater than 10.5 volts?
Yes Ground circuit from battery negative post to MAF sensor is
okay.
Go to step 8.
No
Go to next step.
7
CHECK MAF SENSOR GROUND CIRCUIT
CONTINUITY
• Key off.
• MAF sensor disconnected.
• Breakout box installed.
• Disconnect PCM.
• Disconnect NGS tester from DLC.
• Measure resistance between ground circuit
at MAF sensor vehicle harness connector
and battery negative post.
• Is resistance less than 10 ohms?
Yes Ground harness circuit to MAF sensor is okay.
RECONNECT NGS tester.
Go to next step.
No
SERVICE open in ground harness circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
d
* After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
8
CHECK PCM GROUND CIRCUIT (BETWEEN
PCM AND MAF SENSOR GROUND
CIRCUIT) CONTINUITY
• Key off.
• MAF sensor disconnected.
• Breakout box installed. PCM disconnected.
• Measure resistance between PCM ground
circuit at MAF sensor vehicle harness
connector and Test Pin 36 at breakout box.
• Is resistance less than 5.0 ohms?
Yes
PCM ground harness circuit to PCM is okay.
Go to next step.
No
SERVICE open in PCM ground harness circuit.
REMOVE breakout box.
RECONNECT ail components.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
9 CHECK MAF SIGNAL CIRCUIT FOR SHORT
TO GROUND IN PCM
• Key off.
• MAF sensor disconnected.
• Breakout box installed.
• Reconnect PCM to breakout box.
• Disconnect NGS tester from DLC (if
applicable).
• Measure resistance between Test Pin 88
and Test Pins 36 and 24 or 103 (PWR
GND) at breakout box.
• Is each resistance greater than 10,000
ohms?
Yes RECONNECT NGS tester.
Go to next step.
No
MAF signal circuit short to in PCM.
REMOVE breakout box.
RECONNECT MAF sensor.
RESET PCM to completely clear DTCs.
a
y
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
10
CHECK MAF SIGNAL CIRCUIT OUTPUT
• Key off.
• MAF sensor connected.
• Breakout box installed. PCM connected.
• Key on, engine running.
Note
• If stabilized idle is not stabilized at
minimum of 700 rpm, go to ENGINE
SYMPTOM TROUBLESHOOTING.
•
Measure voltage between Test Pin
88
at
breakout box and battery negative post.
• Is voltage at idle between 0.34 and 1
.96
volts?
Yes MAF signal circuit to PCM is okay.
Go to next step.
No
MAF signal circuit or ground circuit is open in the MAF
sensor, or MAF signal circuit is shorted to PCM ground
circuit in the MAF sensor.
REPLACE MAF sensor.
REMOVE breakout box.
RECONNECT PCM.
RESET PCM to completely clear DTCs.
I w
A fter Repair P rocedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
c 1-0 1 A - 1 3