Overhaul - 4R70W Automatic Transmission: Description
4R70W is a 4-speed, automatic with electronic shift, converter clutch and line pressure controls. It uses a double-pinion compound gearset to produce 4 forward speeds and reverse. It uses 2 bands, 2 one-way roller clutches and 4 friction clutches to hold or drive the planetary gearset members. See Fig 1 .
Shift control solenoids provide gear selection and are controlled by the EEC microprocessor. For additional information on the EEC system, refer to appropriate TESTS W/CODES article in ENGINE PERFORMANCE section.
The EEC system has self-diagnostic capabilities. Fault codes for faulty engine and transmission sensors, switches and circuits are stored in the PCM and may be retrieved to aid diagnosis and repair.