I. Core Specifications (OEM Specifications)

Part Number: 704‑21600 (also written as 704/21600)

Brand: JCB (British Construction Machinery)

Voltage: 12VDC (Standard for JCB Construction Machinery)

Type: PCB-Integrated Steering Mode Control Module (includes relays + logic circuitry)

Functions:

Switching between 2-wheel and 4-wheel steering modes

Steering angle signal processing

Steering assist / Direction lock control

Terminals: 6-pin waterproof connector (with color-coded wiring harness: Red / Black / Yellow / Green / White / Brown)

Protection Rating: IP54 (Dustproof and water-resistant; resistant to construction site vibration)

Material / Dimensions: Black flame-retardant plastic housing; approx. 110 × 70 × 40 mm

Weight: Approx. 1.02 kg

Operating Temperature: ‑30°C to +70°C

II. Applicable Models (Precise Compatibility)

JCB Backhoe Loaders

4CX (Serial Numbers: 400001–409445)

3CX Series

JCB Telehandlers

525‑58, 525‑67, 527‑58, 527‑68

520‑40, 524‑50

III. Common Faults and Replacements

Fault Symptoms: Inability to switch steering modes; 4-wheel steering locked/stuck; heavy steering; indicator lights failing to illuminate

OEM Replacement: 704/21600 (The sole original part number; no alternative OEM part available)

Aftermarket Replacement: Domestic replica version (must match the 6-pin configuration + 12V logic)

Non-Interchangeable Parts: D147166 (Case 12V Flasher), DCNPT200‑01 (XCMG 24V High-Current Module), etc.—these differ in function, voltage, and pin configuration.