Toyota 4-Runner 1985 Repair Manual page 239

FI-70
EFI SYSTEM -
Electronic Control System
INSPECTION OF OX SENSOR
1. Warm-up the engine.
2. Connect a SST to the 4-terminal connector. SST 09842-14010
3. Using a voltmeter connect the positive probe to the red wire of the SST and negative testing probe
to the block wire.
4. Warm up the Ox sensor with the engine at 2,500 rpm for about 90 seconds.
Maintain engine speed at 2,500 rpm.
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Check that the needle of the voltmeter fluctuates 8 times
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8 times or more
~----------------------~
or more in 10 seconds.
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Less than 8 times
Is there 3.75 V or more with the engine
running?
NO YES
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Repair
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Remove the PCV hose on the lower flow side of YES
Zero
Less than 1.25 V ?
YES
the throttle valve and race the engine to 2,500
n
rpm. Check that the needle fluctuates 8 times or .-"-C-h--.l..
k
-
t
-
h
--.--.-
t
.-------.
NO
BAD
ec e Ignl Ion
more in 10 seconds.
t-------------.l.,.
system.
NO
Replace Ox sensor.
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OK
Check for fouled
spark plugs.
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Several dirty
plugs
All dirty
Re-warm the Ox sensor.
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Is there 0 V when Ox
sensor is disconnected
while the engine is
running?
NO
YES
Normal
CONTINUED
ON PAGE FI- 71
Repair
Replace injector.
Repair
Replace ECU.
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