4
ENGINE TIMING CHECK (EEC-IV SYSTEMS)
IMPORTANT: Before performing the KOER Self Test, the
vehicle's Ignition Base Timing and the computer's ability to
electronically control timing advance must be checked for
proper operation. Maladjustment of ignition timing, or a
problem in the advance circuit, might generate false fault codes
when performing the KOER Self Test that would cause the test
to be invalid. Use the following procedures to check for proper
ignition timing and to verify the computer's ability to
electronically advance ignition timing.
This procedure is used to check for proper ignition timing, and
to verify the computer's ability to electronically advance
ignition timing.
•
For 1992 and older vehicles, the Code Reader can be used
in combination with a timing light to check ignition timing
and the vehicle's computer ability to advance ignition
timing. Follow the procedures in paragraph "A".
•
For 1993 and newer vehicles, follow procedures in
paragraph "B".
A.
Timing Procedures for 1992 and Older Vehicles (excluding
diesel engines)
•
Always observe safety precautions before and during Self-
Test.
•
ALWAYS check Code Reader battery before retrieving
fault codes.
•
A timing light is required to perform this test.
•
The vehicle must pass the KOEO test before performing
this test.
Turn ignition off.
1.
Turn the Code Reader off (press the ON/OFF button, as
2.
necessary), then connect the Code Reader to the vehicle's
test connectors.
Both the large and small connectors must be
connected.
3.
Start the engine.
Press and release the ON/OFF button to turn the Code
4.
Reader "ON".
Chapter 4
Retrieving Codes
ENGINE TIMING CHECK (EEC-IV SYSTEMS)
30