Vref (Reference Voltage) - Mazda B-Series 1997 Workshop Manual

FT
ON-BOARD DIAGNOSIS SYSTEM
Pinpoint Test VREF (Reference Voltage)
INSPECTION
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ACTION
greater than 6.0 volts when measured in the Yes
previous step?
,
No
Key ON, engine off.
Is voltage across battery
terminals
greater than 10 5
volts?
Yes Reconnect IAC solenoid connector.
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Go to next step.
Go to step 15.
Go to next stew.
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Yes Go to next step.
No Inspect charging system (refer to sectlon G)
-
--
5
Key ON, engine off. I
Measure voltage between VPWR circuit at IAC solenoid
NO
Repair open VPWR circuit,
connector and battery negative terminal.
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Key ON, engine off.
,
Yes Go to next step.
Disconnect sensor where VREF check fa~led.
Measure voltage between battery positive terminal and
SIG RTN circult at appropriate sensor connector
1
No Go to step 10.
Is voltage greater than 10.5 volts and w~thin 1 . O volt of
battery voltage?
Note: The purpose of this step is to determine if scan
Yes
/
Go to step 9
tool or NGS is able to communicate with PCM.
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Key ON, englne off.
Attempt to access ECT PID.
No 1 Go to next step.
Can ECT PID be accessed?
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Key OFF.
Disconnect TP sensor connector.
Disconnect IAC solenoid connector.
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Is voltage greater than 1 6 5 volts?
6 Key OFF.
Leave TP sensor disconnected.
Disconnect DPFE sensor connector.
Key ON, engine off.
Measure voltage between VREF and SIG RTN circuits at
TP sensor connector.
Is voltage between 4.0 and 6.0 volts?
Yes Replace DPFE sensor.
No Go to step 7.
Key OFF.
Disconnect TP sensor connector.
Install breakout box, leave PCM disconnected.
Key ON, engine off.
Measure voltage between VPWR test pin 71 and PWR
GND test pin 77 at breakout box.
Yes Go to next step.
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No Repair open VPWR circuit between PCM and
PCM relay.
1 /
Is voltage greater than 10.5 volts?
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Key OFF.
Leave TP sensor connector disconnected.
Disconnect scan tool or NGS from data link connector.
Measure resistance between VREF test pin 90 and PWR
GND test pins 51/103 at breakout box.
Is resistance greater than 10,000 ohms?
Key OFF.
Disconnect sensor connector where VREF check failed.
Install breakout box, leave PCM disconnected.
Measure resistance between VREF test pin 90 and VREF
circuit at appropriate sensor connector.
Is resistance less than 5.0 ohms?
- -
Note: The purpose of this step is to determine if scan
tool or NGS is able to communicate with PCM.
Key ON, engine off.
Attempt to access ECT PID.
Can ECT PID be accessed?
Are KOEO DTCs present for two or more sensors
connected to
SIG
RTN circuit?
Sensors conn cted to SIG RTN:
DPFE sensor, TP sensor, IAT sensor, ECT sensor, OCT
ADJ connector, TR sensor, H02S-11, H02S-12,
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H02S-21. CPP switch. PSS switch
1
Yes Replace PCM.
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'
Yes
/
Replace PCM.
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No Repair open VREF circuit.
/
Yes
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Go to next step.
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1 1
No
Go to step 13.
,
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1
Yes
GO to next step.
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1
No
(
Repair open SIG RTN circuit to sensor where
VREF check failed.
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