Description of On-Board Diagnostics

Preliminary Check Procedure:

GENERAL DIAGNOSIS INFORMATION

The AW-4 is an electronically controlled transmission. Shift points and sequence are controlled by the TCU. Before attempting repair, determine if a malfunction is electrical or mechanical.

The TCU used with the AW-4 transmission has a self-diagnostic program that is compatible with the DRB II tester. The tester will identify faults in the electrical control system. A schematic of the TCU circuitry is provided at the end of this section. The diagnosis information in this section will help locate faults in the transmission running gear.

Diagnosis should begin with the Preliminary Check Procedure. It is will help determine if a problem is mechanical or electrical. The first procedure step is Initial Inspection and Adjustment.