1995-1997 Range Rover Automatic Transmission System Information Document. This document is intended to be a guide to the BOSCH Transmission controllers for the ZF 4 Speed Automatic Transmission unit incorporating the Torque Converter (4HP22). The information contained within gives the outline functionality, architecture and electrical specification. There should also be enough information to diagnose any system fault, which is complemented with a fault diagnosis tree.
The diagnosis of automatic transmission faults requires that the technician take a systematic approach to the determination of the fault involved. There are two systems involved; the mechanical operation of the transmission and the electronic control of the transmission via the Transmission Control Module (TCM). It is important to realize that a mechanical problem can set a Diagnostic Trouble Code (DTC) and also that an electronic failure can produce a mechanical symptom.
The following flowchart will help to direct you to the area requiring investigation first.
The information following the chart is split into 2 key areas:
- System Information
- Electrical Symptoms
The ZF 4HP22/24 automatic transmission is basically the same as the previous ZF automatic transmission with the addition of electronic control over the pressure regulator, torque converter lockup and shift valves.
Mechanical selection of Park, Reverse, Neutral and Drive is the same on both Mechanical and Electronic Transmissions. This allows the vehicle to be operated in Limp Home Mode if the electronic controls fail. The mechanical diagnosis of the transmission is the same as before and would require the same repair procedure.
Refer to the following schematic to graphically demonstrate the interconnection of the various
control units used in the operation of the electronically controlled transmission.
- VEHICLE INTERFACE REQUIREMENTS
- DESCRIPTION OF FUNCTIONALITY
- FAULT FINDING
- FAULT CODES
- GENERAL INFORMATION
- FAULT TREE ANALYSIS
Size: 931 Kb
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