Key On/Engine Off (KOEO) Self-Test

There are 4 codes displayed during this test. The first is a Fast code, which is not applicable in field testing. Fast codes are represented by slight needle deflections on analog VOM or flickering LED on STAR tester. These are standard service codes being run at a rate too high for the testers to read. Fast codes are used by automatic equipment during manufacturing processes.

In order of display, the next 3 codes used for this test are the On Demand code, the Separator code, and the Continuous/Memory code. The first service code shown in this test sequence is the On Demand code. The On Demand code indicates a malfunction which is present at time of testing. This type of malfunction is called a "hard fault".

The second code is the Separator code, which indicates that On Demand codes have ended and Continuous/Memory codes are about to start. The third code is the Continuous/Memory code, which indicates a recent problem which is not present at time of test (intermittent fault).

The On Demand first digit is indicated by a pulse or pulses, after which the needle drops to zero for 2 seconds before the second digit of the code is indicated as a pulse or pulses. After a pause of 6-9 seconds, the Separator code (single digit on VOM; 10 on STAR tester) will be displayed for 1/2 second. After 6-9 seconds, the first digit of the Continuous/Memory code will be indicated, the needle then dropping to zero for 2 seconds, and then the second digit of the Continuous/Memory code will be indicated.

NOTE: If engine will not start, go to Circuit Test A. If engine stalls while testing, go to Diagnosis By Symptom Test which can be found in specific engine section.