Instruction Manual

18
Self-Test Part 4: Key On Engine Running (KOER) Self-Test.
IMPORTANT: You must complete all steps in Self-Test Parts 1,2 and 3 before
proceeding to Part 4.
Verify good battery in Code Scanner (Section 2).
1) Verify Ignition Key is in OFF
Position.
2) Put Code Scanner HOLD/TEST
Switch in HOLD 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.
3) Start the Engine.
• If engine will not start, stalls or runs
rough, refer to vehicle service
manual for troubleshooting charts
related to the symptom.
4) Run the Engine to Warm the EGO
Sensor.
• The EGO (Exhaust Gas Oxygen)
sensor must be warmed-up to
operate for this test.
• Run engine at 2000 RPM for at
least 2 minutes.
5) Turn Engine OFF – Wait 10
Seconds – Restart Engine.
6) Put Code Scanner HOLD/TEST
Switch in TEST Position.
• This starts the KOER (Key On
Engine Running) Self-Test.
7) Get Engine Identification (ID) Code
from the Flashing STO Light.
NOTE: If the light does not flash, go
back and repeat SELF-TEST PART 4
starting with Step 5. If the light still
does not flash, you have a problem
which must be repaired before
proceeding. Refer to the vehicle
service manual “No Codes” trouble-
shooting chart.
• An engine ID code is sent after a
few seconds to signal the beginning
of KOER Self-Test.
• Count flashes on the STO light.
– 4 cylinder: 2 Flashes.
– 6 cylinder: 3 Flashes.
– 8 cylinder: 4 Flashes.
– 7.3L Diesel: 5 Flashes.
IMPORTANT: Some actions may be
required at this time.
• Vehicles with PSPS (Power Steering
Pressure Switch): Turn steering
wheel one half turn and release
within 1 or 2 seconds AFTER
seeing engine ID code. (The
computer checks for switch action.)
• Vehicles with BOO (Brake On/Off
switch) when used by computer:
Press and release the brake pedal
AFTER seeing engine ID code. (The
computer checks for switch action.)
• Vehicles with OCS (Overdrive
Cancel Switch): Toggle the switch
on and off AFTER seeing engine ID
code. (The computer checks for
switch action.)
8) Perform WOT Action After
“Dynamic Response” Signal.
• The Dynamic Response signal is a
single flash on the STO light
occurring 6 to 20 seconds after the
engine ID code is sent.
❊
DYNAMIC RESPONSE