Automatic Transmission - Diagnosis - 4R44E & 4R55E Automatic Transmission: Introduction
NOTE:
For 4R44E and 4R55E transmission mechanical testing and repair, see AUTO TRANS OVERHAUL - FORD 4R44E & 4R55E article.
The first step in diagnosing any driveability problem is verifying the customer's complait with a test drive under the conditions the problem reportedly occurred. Before entering self-diagnostics, perform a careful and complete visual inspection. Most transmission control problems result from mechanical breakdowns or poor electrical connections.
NOTE:
Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.