Mazda MX-6 1998, Workshop Manual, Page: 378 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION ACTION
10 Note
• Purpose of this step is to determine if NGS
tester is able to communicate with PCM.
Yes Go to next step.
Key ON, engine off.
Attempt to access ECT PID.
Can ECT PID be accessed?
No Go to step 13.
11 Are KOEO DTCs present for two or more
sensors connected to ground circuit?
Sensors connected to ground circuit:
EGR boost sensor, TP sensor, IAT sensor,
ECT sensor, FTP sensor, TR switch, H 02S
(Front RH), H 0 2 S (Front LH), H 20S (Middle),
H 20S (Rear), clutch switch, PSP switch, ATF
Temperature sensor.
Yes Go to next step.
No
Repair open fround circuit to sensor where constant
voltage circuit check failed.
12
Key OFF.
Disconnect NGS tester from DLC.
Disconnect sensor connector where constant
voltage circuit check failed.
Install breakout box. Leave PCM
disconnected.
Measure resistance between ground circuit at
appropriate sensor connector and test pin 91
at breakout box.
Is resistance less than 5.0 ohms?
Yes Reconnect sensor connector.
Go to next step.
No Repair open ground circuit.
13 Key OFF.
Disconnect NGS tester from DLC.
Install breakout box. Leave PCM
disconnected.
Yes Go to next step.
Measure resistance between battery negative
terminal and test pins 51/76/77/103 at
breakout box.
Is each resistance less than 5.0 ohms?
No Repair open ground circuit to ground.
14 Key OFF.
Connect PCM to breakout box.
Measure resistance between test pin 91 and
test pins 51/76/77/103 at breakout box.
Is each resistance less than 5.0 ohms?
Yes
Ground circuits are okay.
No Replace PCM.
15 Key OFF.
Disconnect sensor connector where constant
voltage check failed.
Disconnect TP sensor, fuel tank pressure
sensor and EGR boost sensor connectors.
Disconnect PCM connector.
Key ON, engine off.
Measure voltage between constant voltage
circuit at TP sensor connector and battery
negative terminal.
Is voltage less than 0.5 volts?
Yes Replace PCM.
No
Repair constant voltage short to power in harness.
0 1 -0 1 B -1 7 2