Mazda B-Series 1997 Workshop Manual page 461

FT
ON-BOARD DIAGNOSIS SYSTEM
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STEP
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INSPECTION ACTION
Key OFF.
Disconnect vacuum hose at EGR valve and connect hose
to vacuum gauge.
Start engine and run it at idle.
While monitoring vacuum gauge, disconnect EVR solenoid
connector.
Does vacuum reading remain greater than 1.6 in-Hg at idle
even after EVR is electronically disconnected?
Yes Go to next step.
NO
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GO to step 7
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Key OFF.
Disconnect vacuum hoses from EVR solenoid.
Remove EVR solenoid vent cap if equipped.
Remove filter and inspect for blockage or icing in case.
Plug vacuum supply port on EVR solenoid.
Apply 10 to 15 in-Hg of vacuum directly to EVR vacuum
source port with a hand vacuum pump.
-
If vacuum holds or is slow to release to
atmosphere, the EVR vent could be plugged or
restricted.
Is EVR vent or vent filter plugged or restricted?
Yes
(
Repair or replace EVR solenoid.
Go to step 13.
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Replace EVR solenoid.
Go to step 13.
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7
/Key OFF. Yes
/
Go to next step.
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Disconnect EVR solenoid connector.
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vacuum is released.
1
-
A slow-to-return voltage could be an indication of a
binding or a slow-closing EGR valve.
Does DPFEGR PID voltage indicate an open, binding or
slow-closing EGR valve?
Measure resistance across EVR solenoid.
No
stalling engine and release vacuum.
Repeat several times while observing DPFEGR PID.
-
DPFEGR PID voltage should increase as valve
begins to open and return to initial voltage as
Replace EVR solenoid.
No
Is resistance between 26 and 40 ohms?
Go to step 13.
- - -
. .
--
Replace PCM.
Leave EVR solenoid connector disconnected.
Go to step 13.
Install breakout box, leave PCM disconnected.
Is resistance between EVR test pin 47 and PWR GND test
pins 5111 03 at breakout box greater than 10,000 ohms?
~
- - - - -
Key OFF.
Disconnect pressure hoses at DPFE sensor.
Connect a hand vacuum pump to downstream pickup
marked "REF on DPFE sensor.
Key ON, engine off and access DPFEGR PID.
Apply 8-9 in-Hg vacuum to DPFE sensor.
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PID voltage should be above 4.0 volts.
/
Quickly release vacuum from sensor,
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PID voltage should drop to less than 1 volt in less
than 3 seconds.
Does DPFEGR PID indicate a fault in DPFE sensor?
Reconnect EGR vacuum hose.
Go to next step.
10 Key ON, engine off.
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Yes
Access DPFEGR PID and note voltage.
Note: DPFEGR PID is 0.45
+
0.25 volts.
Inspect EGR valve for signs of contamination,
unusual wear, carbon deposit, binding and
other damage.
Disconnect vacuum hose at EGR valve and plug hose.
Connect a hand vacuum pump to EGR valve.
Start engine and run it at idle.
Observe DPFEGR PID at idle and compare to KOEO
voltage.
Apply just enough vacuum to EGR valve to open it without