AITO M5 High-Voltage System Safe Operation Guide

Fault Background

The high-voltage system of the AITO M5 (EREV) covers the battery pack assembly, on-board charger (OBC) assembly, AC/DC charge ports, five high-voltage wiring harnesses (battery pack front/rear, front motor, rear motor, PTC-compressor), and front/rear drive motor assemblies (front HW165 / rear HW200). The manual states safety discipline extremely clearly—follow it on site: Before work, it is prohibited to wear metal accessories such as gold/silver jewelry and watches; insulated professional tools, insulated gloves, and insulated shoes must be used; bare-hand operation without protective equipment is strictly prohibited; the work sequence is uniformly disconnect the 12V battery negative terminal → remove the manual service disconnect switch → drain coolant → then work on the target component; and high-voltage and battery system repairs must be performed by certified technicians with battery expertise, an electrician's license, and Seres technical training and authorization. On-site protective equipment also includes safety goggles and CO2/dry powder fire extinguishers. This article organizes safety discipline, work sequence, and disassembly/assembly points for each high-voltage component into a reference guide.

Safety Discipline (Manual Wording)

Disassembly/Assembly Points for Each Component

Battery pack assembly: Disconnect 12V battery negative terminal → drain coolant (refer to "Cooling System Drain and Fill, 03.100 Range Extender Cooling System General Procedure") → remove fasteners and connectors per manual (with insulated gloves).

On-board charger (OBC) assembly: Disconnect 12V battery negative terminal → drain coolant → remove manual service disconnect switch → disconnect the connector between the charge port and OBC → remove fasteners per manual.

Front/rear drive motor assemblies (HW165 / HW200): Wear full insulated equipment → remove front/rear subframe assembly → drain coolant → disconnect high/low-voltage connectors and coolant hoses → remove mounting bolts and take down assembly (insulated ratchet wrench socket set).

High-voltage wiring harnesses (battery pack front/rear, front motor, rear motor, PTC-compressor): Disconnect 12V battery negative terminal → remove manual service disconnect switch → remove related trim and underbody panels → disconnect high-voltage connectors at both ends → remove along routing and wrap connectors with insulating tape.

Charge ports (AC/DC): Remove per charging system chapter, noting to disconnect connectors to OBC/high-voltage harness.

Key Diagnostic and Repair Insights

• The "three firsts" for all high-voltage work: first disconnect negative terminal, then remove service disconnect switch, third drain coolant—missing a step may result in live work;
• After disconnecting high-voltage connectors, insulate immediately to prevent foreign objects and moisture;
• Range extender models share the coolant drain procedure (03.100 Range Extender Cooling System); any water-cooled high-voltage component replacement must first drain coolant;
• After reassembly, refill coolant and bleed air per manual, then restore service disconnect switch and negative terminal.

Safety Warnings

• This article is for technical reference only; high-voltage and battery system repairs must be performed by qualified technicians (battery expertise + electrician's license + Seres training authorization) per OEM specifications; readers unfamiliar with these procedures are strictly prohibited from performing work themselves.
• Remove all metal accessories before work; insulated gloves, insulated shoes, and insulated tools are mandatory; bare-hand operation without protective equipment is strictly prohibited.
• High-voltage work sequence: disconnect 12V battery negative terminal → remove manual service disconnect switch → drain coolant; all steps are mandatory.
• Safety goggles and CO2/dry powder fire extinguisher must be available on site; high-voltage connectors must be insulated immediately after disconnection.
• After removal, store the service disconnect switch properly to prevent accidental reinstallation and live work.

Repair Insights

The AITO M5 manual treats safety discipline as a "pre-work prerequisite" rather than a "caution": qualification threshold (battery expertise + electrician's license + Seres technical training authorization), jewelry ban (gold/silver jewelry and watches must be removed—metal accessories are moving short-circuit points in high-voltage work), sequence rule (negative terminal → service disconnect switch → drain coolant). The second and third items are the most likely to cause accidents: metal accessories are often overlooked, and the service disconnect switch is often skipped. Structurally, remember the model characteristics: the EREV has a shared "range extender cooling system" drain procedure (03.100), and the front HW165 / rear HW200 dual drive motors with five high-voltage harnesses form a complete high-voltage network; any water-cooled high-voltage component (battery/OBC/motor) must have coolant drained before disassembly. Memorize the tool list: insulated ratchet wrench socket set, insulated wrenches, cross-head insulated screwdrivers, insulated gloves, insulated shoes, safety goggles, fire extinguisher—do not start work if any item is missing.

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【This article is for reference only】