Engineering Deeper: EV Electrical Architecture, Scalability, and Serviceability

Electric vehicle (EV) innovation doesn’t stop with batteries and motors. The electrical and electronic architecture (EEA) that underpins vehicle communication, diagnostics, and control systems is equally critical. In this in-depth teardown analysis, Munro & Associates explore the EEA strategies behind Tesla’s Model Y, Ford’s Mustang Mach-E, and Volkswagen’s ID.4 with an electrical architecture comparison. What emerges is a layered understanding of how scalability, weight reduction, and serviceability trade-offs shape modern EV design.

The Scaling Challenge: Architecture Philosophies Compared

Tesla’s approach to EEA is rooted in integration and forward scalability. With just 25–26 ECUs, Tesla condenses functionality into three major controllers—left, right, and front body controllers—and a powerful domain controller managing Autopilot functions. This “clean sheet” approach minimizes harness complexity and positions Tesla for rapid OTA (over-the-air) upgrades and future feature integration.

In contrast, Ford and Volkswagen maintain legacy architectures. The Mach-E uses 51 ECUs and the ID.4 52. These higher counts stem from carryover parts and modular designs—choices that favor rapid development but embed future limitations.

Insight:

• Tesla optimizes for scalability, with fewer modules and clear pathways to high-speed communication upgrades.
• Ford and VW prioritize immediate cost containment and supply chain leverage.

Weight Reduction: The Unsung Hero of Electrical Design

Every kilogram counts in EVs. Wiring harnesses, connectors, fuses, and ancillary components can quietly add tens of pounds—dragging efficiency.

• Tesla’s Strategy: Centralizing control reduces cabling. Harnesses plug directly into controllers without intermediate junctions, cutting wire length, connector count, and weight.
• Ford and VW Strategy: More ECUs mean more interconnects, redundancy, and longer harness runs. Even small legacy decisions, like older gauge standards, compound into meaningful weight penalties.

Quantitative Impact: Munro estimates that Tesla’s architecture saves several kilograms compared to a typical legacy design—the equivalent of thousands of dollars in battery cost at the system level.

Key Materials Difference: Tesla’s wiring also tends to favor smaller gauge wires where feasible, thanks to advanced connector design and thoughtful current management.

Serviceability Trade-offs: Modular vs Integrated

Traditional automotive thinking favors modularity: if a door module fails, swap the door ECU. Ford and Volkswagen maintain this logic in their EV designs.

Tesla, by contrast, integrates many functions into fewer, more complex units. A failure might require replacing an entire left-body controller—a higher-cost part but one that is statistically less likely to fail thanks to fewer connectors and hardened designs.

Trade-Offs:

• Tesla: Lower probability of failure, but higher replacement costs if failures occur.
• Ford/VW: Easier and cheaper part-specific replacements but higher system complexity and failure risk.

The Evolution of In-Vehicle Networking: CAN, LIN, and Ethernet

Networking in these EVs showcases diverging philosophies:

• Tesla: Uses 10 CAN buses, with selective CAN FD (Flexible Data-Rate) deployment, allowing potential quadruple speed gains when needed. Ethernet is reserved primarily for diagnostics and Autopilot-domain communication.
• Ford and VW: Both deploy 9-13 CAN buses, often retaining lower-speed (500 kbps) traditional CAN standards. Volkswagen heavily embraces Ethernet (100 Mbps) for camera and infotainment systems.

Serviceability Note: More Ethernet nodes can complicate servicing. Ethernet networks, while fast, require different diagnostic tooling and expertise compared to CAN.

Fuse Systems: eFuses vs Traditional Fuse Blocks

Tesla replaces traditional physical fuses with eFuses—software-controlled silicon switches that reset remotely. Ford and VW still use standard replaceable fuses.

Advantages of Tesla’s eFuses:

• OTA resetting reduces service visits.
• Automatic diagnostics and rerouting capabilities improve uptime.
• Weight reduction by eliminating bulky fuse panels.

Challenges:

• If the main controller fails, a significant portion of the vehicle may lose functionality.
• Service shops must adapt to new diagnostic and reset procedures.

Domain and Zone Controllers: Futureproofing the Platform

Tesla’s structure—with its blend of domain and zone controllers—mirrors emerging best practices for future AV (autonomous vehicle) scaling.

• Domain Controller: Autopilot and Gateway ECU handle advanced processing, high-speed data routing, and security.
• Zone Controllers: Local controllers (left, right, front) reduce wire lengths and localize fault domains.

Volkswagen appears to move toward this structure with its ICAS-1 and ICAS-3 modules and planned ICAS-2 for autonomy. Ford’s approach in the Mach-E is less aggressive but shows signs of evolving in the same direction.

Strategic Advantage: Fewer zones and integrated domains simplify OTA updates and enable centralized computing—essential for Level 3+ autonomy.

Legacy Constraints: A Hidden Cost

Ford and VW’s reliance on parts-bin components introduces hidden costs:

• Heavier wiring due to legacy connectors and wire gauge standards.
• Increased failure points with more connectors and modules.
• Difficulty integrating new features requiring high-speed data paths.

Strategic Implication: Short-term cost savings from reusing modules may result in long-term competitiveness challenges against more agile, clean-sheet competitors.

Preparing for 48-Volt Systems: Tesla’s Head Start

Although current EVs operate on 12-volt systems, Tesla’s streamlined wiring and modular zones position it well for a future shift to 48-volt low-voltage architectures.

• Higher voltage allows thinner wires, lighter harnesses.
• Supports growing accessory power demands (advanced sensors, powerful infotainment systems).
• Improves energy efficiency by reducing current losses.

Tesla’s architecture would require fewer changes to pivot to 48V than Ford or VW’s heavier, fragmented systems.

Final Analysis: Competitive Advantages and Emerging Challenges

Tesla’s Model Y demonstrates a competitive advantage in scalability, weight, and electrical efficiency. However, its approach demands robust quality assurance, as larger integrated modules mean bigger consequences for individual failures.

Ford and Volkswagen, meanwhile, maintain faster-to-market strategies built on modularity but risk higher maintenance costs and difficulty scaling to new technological demands.

Actionable Takeaways for Engineers and Strategists:

• Prioritize integration without sacrificing fault isolation.
• Build modularity where serviceability demands it—but aim to reduce connector count whenever possible.
• Plan for 48V evolution by minimizing legacy dependencies.
• Design electrical architectures that favor OTA update simplicity and centralized diagnostics.

Closing Thoughts: A New Race in EV Engineering

The EV arms race is no longer just about range or battery chemistry. Electrical architecture—invisible to the consumer—may ultimately decide winners and losers as EV technology scales toward mass adoption and autonomy.

Tesla leads today. But Ford and Volkswagen are adapting—slowly but surely. Understanding the nuances of their approaches provides engineers, investors, and enthusiasts a window into the next great leap in automotive technology.

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