ZF 4HP 16 Automatic Transaxle

The ZF 4HP 16 is a 4-speed automatic transaxle designed for cars with front-wheel drive and with a transversely mounted engine.

The transaxle has a hydrodynamic torque converter with a controlled slip lockup clutch.

A planetary gear train establishes the mechanical gear ratios. The integral constant ratio can be adapted to the engine power output and the vehicle weight. The electronic-hydraulic control makes controlled power shifts and various shift programs possible. In Park position, the output is locked mechanically.

The ZF 4HP 16 transaxle operates without freewheels. Shifting between individual gears occurs using overlapping clutch engagement and release.

Overlap shifting provides the following advantages:

The transaxle is a more compact design and lighter because of the absence of freewheels and the lower number of shift elements.
The transaxle reduces the drag losses, resulting in higher efficiency.
A lower number of peak torques acting on the components and driveline.

However, overlap shifting requires high-performance hardware and software and precision engine signals.

NOTE: Lack of basic knowledge of this powertrain when performing diagnostic procedures could result in incorrect diagnostic performance or damage to powertrain components. Do not attempt to diagnose a powertrain problem without this basic knowledge.

The ZF 4HP 16 automatic transaxle consists primarily of the following components:

Mechanical

A torque converter with torque converter clutch (TCC)
A drive link assembly
Two multiple disk clutch assemblies: Clutch B, E
Three multiple brake assemblies: Brake C, D, F
A lock-up clutch valve
Two planetary gear sets
An oil pump
A final drive and differential assembly

Electronic

Two shift solenoid valves: 1, 2
Four pressure control solenoid valves
Two speed sensors: A/T input shaft speed (ISS) and A/T output shaft speed (OSS)
A fluid temperature sensor
An automatic transaxle control module (TCM)
A wiring harness assembly