Mazda MX-6 1998, Workshop Manual

Page: 301 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION ACTION
5
CHECK MAF 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.
• Measure resistance between Test Pin 88
and Test Pins 36 and 24 or 103 at breakout
box.
• Is each resistance greater than 10,000
ohms?
Yes RECONNECT NGS tester.
Go to next step.
No MAF signal circuit shorted to MAF sensor ground or PCM
ground circuit in PCM.
REMOVE breakout box.
RECONNECT MAF sensor.
RESET PCM to completely clear DTCs.
f t
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
6
CHECK PCM GROUND CIRCUIT (BETWEEN
PCM AND MAF SENSOR GROUND
CIRCUIT) FOR SHORT TO GROUND
CIRCUIT IN PCM
• Key off.
• MAF sensor disconnected.
• Breakout box installed.
• PCM connected to breakout box.
• NGS tester disconnected from DLC.
• Measure resistance between Test Pin 36
and Test Pins 51 or 103 at breakout box.
• Is resistance greater than 10,000 ohms?
Yes RECONNECT NGS tester.
Go to next step.
No PCM ground circuit shorted to ground circuit in PCM.
REPLACE PCM.
REMOVE breakout box.
RECONNECT all components.
RERUN OBD Test.
7 CHECK MAF SENSOR 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 between 0.34 and 1.96 volts at
idle?
Yes MAF signal circuit to PCM is okay.
Go to next step.
No MAF signal circuit or MAF sensor ground circuit is open in
MAF sensor, or MAF signal circuit is shorted to PCM
ground circuit in MAF sensor.
REPLACE MAF sensor.
REMOVE breakout box.
RECONNECT PCM.
RESET PCM to completely clear DTCs.
f t
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
8
VERIFY MAF SENSOR CIRCUIT INPUT AND
OUTPUT
• Key off.
• MAF sensor connected.
• Breakout box Installed.
• PCM connected.
• Key on, engine running.
• Measure voltage between Test Pin 88 and
Test Pin 36 at breakout box.
• Is voltage between 0.34 and 1.96 volts?
Yes PCM ground circuit in MAF sensor is okay.
Go to next step.
No PCM ground circuit open in MAF sensor.
REPLACE MAF sensor.
REMOVE breakout box.
RECONNECT PCM.
RESET PCM to completely clear DTCs.
f t
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
9
CHECK MAF SENSOR CIRCUIT OUTPUT
WITH NGS TESTER
• Key off.
• MAF sensor connected.
• Key on, engine running.
• Access MAF PID with
NGS
tester at idle.
• Is MAF PID within specified value?
j y 01-40B MASS AIR FLOW SENSOR
INSPECTION [KL]
Yes
Unable to identify fault at this time.
Check possible intermittent.
Go to SYMPTOM TROUBLESHOOTING No.27.
No
MAF sensor signal circuit or PCM ground circuit is open or
shorted together in PCM.
REPALCE PCM.
REMOVE breakout box.
RECONNECT PCM.
RESET PCM to completely clear DTCs.
f t
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
01-01B -95