Mazda MX-6 1998, Workshop Manual

Page: 195 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
31 CONSTANT VOLTAGE
DESCRIPTION
Incorrect constant voltage
POSSIBLE
CAUSE
Constant voltage circuit malfunction
STEP INSPECTION
ACTION
1
Was constant voltage greater than 6.0 volts
when measured in previous step? Yes Go to step 14.
No Go to next step.
2 Key on, engine off.
Is voltage across battery terminals greater
than 10.5 volts?
Yes Go to next step.
No Inspect charging system.
3
Key on, engine off.
Disconnect sensor where constant voltage
circuit check failed.
Measure voltage between battery positive
terminal and ground circuit at appropriate
sensor connector.
Is voltage greater than 10.5 volts and within
1.0 volt of battery voltage?
Yes Go to next step.
No Go to step 9.
4 Note
• The purpose of this step is to determine if
NGS tester is communicating with PCM.
Key on, engine off.
Attempt to access ECT PID.
Can ECT PID be accessed?
Yes Go to step 8.
No Go to next step.
5
Key off.
Leave TP sensor disconnected.
Disconnect EGR boost sensor connector.
Key on, engine off.
Measure voltage between constant voltage
and ground circuits at TP sensor connector.
Is voltage between 4.0 and 6.0 volts?
Yes Replace EGR boost sensor.
No Go to step 6.
6 Key off.
Disconnect TP sensor connector.
Install breakout box. Leave PCM
disconnected.
Key on, engine off.
Measure voltage between Test Pin 71 and
Test Pin 77 at breakout box.
Is voltage greater than 10.5 volts?
Yes Go to next step.
No
Repair open VPWR circuit between PCM and main relay.
7
Key off.
Leave TP sensor connector disconnected.
Disconnect NGS tester from DLC.
Measure resistance between Test Pin 90 and
Test Pins 51/103 at breakout box.
Is resistance greater than 10,000 ohms?
Yes Replace PCM.
No Repair constant voltage circuit short to ground.
8 Key off.
Disconnect sensor connector where constant
voltage circuit check failed.
Install breakout box. Leave PCM
disconnected.
Measure resistance between constant voltage
Test Pin 90 and constant voltage circuit at
appropriate sensor connector.
Is resistance less than 5.0 ohms?
Yes
Replace PCM.
No Repair open constant voltage circuit.
9 Note
• The purpose of this step is to determine if
NGS tester is communicating with PCM.
Key on, engine off.
Attempt to access ECT PID.
Can ECT PID be accessed?
Yes
Go to next step.
No Go to step 12.
01-01A -1 67