Actron 9640A manual Mode. It is possible to have the Field Service mode funct

GM Historic (OBD I) Diagnostics

Field Service Mode can be operated with the ignition Key On-Engine Off (KOEO) or with the Key On-Engine Running (KOER).

✓Vehicles equipped with climate control computers do not use Field Ser- vice Mode.

✓Some 1994 & 1995 vehicles equipped with a 12-pin ALDL connector with pins A and B shorted will not cause the CHECK ENGINE light to flash codes.

Select Field Service from the GM

Function List and press

ENTER

.

*TAvailablity*Function List

KOEO Procedure

4cord

Data

]

5Review

[

`6)FildServce

~

1) Turn ignition Key ON but DO NOT Start Engine.<Yes>

No

Turn ignition Key On, but do not start

engine. The Check Engine light should

flash. Select YES to continue. If the light

does not illuminate, either the vehicle

speed motor, and obtain DTCs using the CHECKENGINELightNGINE light.Flash?

does not support this test mode, the

lamp is burned-out or circuit problems

exist.

✓ It is difficult to know exactly which GM vehicl

use the Field Service

mode. It is possible to have the Field Service mode funct

on the Func-

5

tion List, and it not be applicable.

If Check Engine light operates, the Field

Service screen is displayed. Pressing

Field

ENTER

will toggle the short to Pins A &

GM

B On and Off.

Press

Continue with either the KOEO procedure or KOER procedu . When done,

press

to return to the GM Function List.

FUNC

are stored n the vehi-

✓ While inFieldService mode, no new trouble cod

cle’s memory.

lays,YourCHECKsolenoids d t

In theKOEOProcedure, Field Service canDochesck

e idle

2) On scan tool, place Field Service On.

3) The Check Engine light will begin to flash co

es.

ach DTC is displayed

three (3) times. The DTCs are displayed starting with the lowest umbered

one. After all DTCs are displayed, the sequence k eps repeating until the

ignition key or Field Service mode is tu n

OFF.

— Count CHECK ENGINE Light Flashes to obtain trouble codes. The fi st

digit is sent first. A short pause separat

digits while a long pause

separates each DTC. All codes conta n 2

igitsServiceENTERToTurn. :OffOn~

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