Overview
The ZF 4644.107.200 SPEEDOMETER is a critical output sensor assembly designed for the WG 181 Series transmission. This OEM genuine part monitors rotational speed from the transmission’s output shaft, converting mechanical motion into an electrical signal for the vehicle’s dashboard and electronic control unit (ECU). Positioned within the rear housing section of the gearbox, it interfaces directly with the 4644101217: TRANSMISSION HOUSING to ensure accurate speed data. The SKU 4644.107.200 is factory-calibrated for precise signal generation, making it essential for shift timing and cruise control functionality in heavy-duty commercial vehicles.
Symptoms of Failure
- Erratic or zero speedometer reading – A failing 4644.107.200 often causes the speedometer needle to jump, drop to zero, or display incorrect speeds, especially during deceleration or low-speed operation.
- Transmission shift hunting – When the speed sensor signal degrades, the ECU may receive inconsistent data, leading to delayed or harsh gear shifts, commonly described as “shift hunting” in WG181 applications.
- Check engine or transmission warning light – Modern diagnostic systems detect speed sensor faults, triggering dashboard alerts and storing error codes such as P0722 (output speed sensor circuit intermittent).
- Loss of cruise control – Without a reliable speed signal from the 4644.107.200, cruise control systems may disengage or fail to activate, a frequent complaint in long-haul trucking fleets.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4644.107.200 |
| OEM Reference | ZF 4644.107.200 |
| Material | Die-cast aluminum housing with stainless steel sensor tip |
| Weight | 0.35 kg (0.77 lbs) |
| Dimensions (L x W x H) | 85 mm x 45 mm x 45 mm |
| Output Signal Type | Hall-effect, 3-wire (VCC, GND, Signal) |
| Operating Temperature | -40°C to +125°C |
| Sealing Class | IP67 (with O-ring installed) |
Compatibility
This speedometer is engineered for the ZF WG181 series but is also compatible with adjacent transmission models in the WG family. It fits the WG180, WG200, and WG210 gearboxes when used with the correct 4644301383: TRANSMISSION HOUSING variant. The sensor mounting pattern matches all WG-series output housings, though the 4644301189: THREADED BUSH must be checked for thread compatibility. For installations requiring a sealed oil drain, the 4475280043: SCREW PLUG is often replaced concurrently to prevent contamination.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101217 | TRANSMISSION HOUSING | Main structural casing for gear train and sensor mounting |
| 4644301383 | TRANSMISSION HOUSING | Alternate housing variant for WG200/WG210 |
| 4644301189 | THREADED BUSH | Provides secure mounting thread for speed sensor |
| 4475280043 | SCREW PLUG | Seals unused sensor ports or oil passages |
| 0634306198 | O-RING | Creates oil-tight seal between sensor and housing |
| 0634801098 | SEALING RING | Prevents fluid leakage at threaded connections |
| 0730365067 | TYPE PLATE | Identification plate for transmission model and serial |
| 0631311009 | GROOVED STUD | Alignment pin for housing assembly |
| 4644301161 | COVER PLATE | Protects internal components from debris |
| 0636100621 | HEXAGON SCREW | Fastener for securing cover plate and housing |
