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Self-Test Part 3:
Key On Engine Running (KOER) Self-Test.
IMPORTANT: You must complete all steps in Self-Test Parts 1 and 2 before
proceeding to Part 3.
For Vehicles With I-4 & I-6 Engines:
(Refer to page 44 for V-6 & V-8
engines.)
1) Verify:
• Ignition Key is in OFF Position.
• Code Scanner is Connected.
• HOLD/TEST Switch is in TEST
Position.
WARNING: The next step involves
starting the engine.
Observe safety precautions.
• Always operate vehicle in a well
ventilated area.
Do NOT inhale exhaust gases –
they are very poisonous!
• Set the parking brake.
• Put shift lever in PARK (automatic
transmission) or NEUTRAL (manual
transmission).
• Block the drive wheels.
• Stay away from moving engine
parts.
2) Start the Engine.
3) Increase and Hold Engine Speed at
3000 RPM Within 20 Seconds of
Start.
• Maintain engine speed at 3000
RPM until service codes are sent
(end of Step 5).
4) Get Engine Identification (ID) Code
from the Flashing STO Light.
• Maintain engine speed at 3000
RPM.
• An engine ID code is sent after a
few seconds to signal the beginning
of KOER Self-Test.
• Count flashes on the STO light.
(Ignore any flashes lasting longer
than 1 second.)
– 4 cylinder: 2 Flashes.
– 6 cylinder: 3 Flashes.
Note: If the light does not flash or
flashes the wrong number, go back
and repeat SELF-TEST PART 3
starting with Step 1. If the light still
does not flash correctly, you have a
problem which must be repaired
before proceeding. Refer to the
vehicle service manual “Self-Test Not
Functional” (or similar title) trouble-
shooting chart.
5) Get Service Codes From the
Flashing STO Light.
• Maintain engine speed at 3000
RPM until codes are sent, then
release throttle and return to idle
RPM.
• Count flashes on the STO light.
This is done the same way as in
Self-Test Part 2. (Ignore any flashes
lasting longer than 1 second.)
Code 12 looks like:
❊
PAUSE
❊❊
FLASH (pause) FLASH FLASH
(FLASH = 1, FLASH FLASH = 2.
(Put 1 and 2 together = code 12.)
• All codes are 2 digits long.
• After all codes are sent, the whole
series is sent again just one more
time (so you can double check your
code list).
