When an electric or hybrid vehicle is involved in a serious collision, its high-voltage battery doesn’t just sit there waiting to become a hazard \u2014 the vehicle’s safety system reacts in under two milliseconds to sever the entire HV circuit before a short can start a fire or electrocute first responders. The device responsible for that reaction is the pyro fuse: a one-shot, signal-triggered safety component that uses a small pyrotechnic charge to permanently cut the main high-voltage busbar the instant crash sensors or the Battery Management System detect a critical event. Understanding how it works matters whether you own an EV, work on them professionally, or just want to know what’s actually protecting you inside a modern electrified vehicle.<\/p>\n\n\n\n
A pyro fuse (also called a pyrotechnic fuse or pyrotechnic safety switch\/PSS) is a one-shot high-voltage safety device found in electric and hybrid vehicles. When triggered by crash sensors or the Battery Management System, a pyrotechnic charge drives a piston to sever the main HV busbar in under one millisecond \u2014 permanently isolating the battery from the inverter, motor, and charger to prevent electrical shock and fire. It cannot be reset or reused; once activated, it must be replaced by a certified high-voltage technician using OEM-specific tooling and diagnostic software.<\/p>\n\n\n\n
The name covers several closely related terms you’ll encounter across OEM documentation and technical literature: pyro fuse, pyrotechnic fuse, pyrotechnic safety switch (PSS), pyro switch, and battery safety terminal (BST). They all describe the same core concept \u2014 a signal-activated, single-use device that physically severs a high-voltage conductor when commanded to do so.<\/p>\n\n\n\n
The key distinction from a conventional automotive fuse<\/a> is how it activates. A standard blade or cartridge fuse blows when excessive current generates enough heat to melt its element \u2014 a passive, thermally driven process that can take milliseconds to seconds depending on the overcurrent magnitude. A pyro fuse is different: it waits for an external electrical signal, then fires a pyrotechnic charge that mechanically destroys the conductor in a fraction of a millisecond regardless of the current flowing through it at that instant. That distinction \u2014 active signal-triggered vs. passive thermal response \u2014 is what makes the pyro fuse uniquely suited to crash protection in high-voltage systems.<\/p>\n\n\n\n Pyro fuses are almost exclusively found in battery-electric vehicles (BEV), hybrid electric vehicles (HEV), and plug-in hybrids (PHEV). Some premium internal-combustion vehicles use a simpler battery safety terminal at the 12V positive post \u2014 functionally related but operating at much lower voltage and energy levels. For EV and hybrid applications, the pyro fuse operates across the 400V to 800V DC range where a thermal fuse would simply be too slow to prevent catastrophic outcomes. For a broader look at how fuses, relays, and power distribution<\/a> work together in automotive electrical systems, that context helps frame why HV protection needs a fundamentally different approach.<\/p>\n\n\n\n Physically, a pyro fuse is a compact, hermetically sealed unit roughly the size of a large electrical connector. Its construction is more sophisticated than it looks from the outside.<\/p>\n\n\n\n The initiator<\/strong> (sometimes called a squib) is the pyrotechnic charge element. It’s a small, electrically activated device \u2014 the same technology lineage as airbag inflators, which is no coincidence given how the two systems work together. When the initiator receives a trigger current, it ignites and produces a rapid gas expansion inside the sealed chamber. That expanding gas drives a piston<\/strong> with enough force to shear through the main HV conductor. The piston tip is made from a non-conductive material \u2014 plastic or ceramic \u2014 which physically isolates the severed busbar ends immediately after the cut, preventing electrical arcing across the gap. This arc suppression is critical: without it, the energy stored in the HV circuit could sustain an arc hot enough to cause secondary damage or fire even after the physical connection is broken.<\/p>\n\n\n\n The busbar<\/strong> is the main conductive element being severed \u2014 a solid copper or aluminium conductor sized to carry the full pack current continuously. The entire assembly sits inside a robust, insulated enclosure rated for the operating environment, with sealed electrical terminals connecting it to the HV circuit on both the battery side and the vehicle load side, plus a separate low-voltage logic connector that receives the trigger signal.<\/p>\n\n\n\n Modern designs come in two trigger configurations. An active trigger<\/strong> design fires only when it receives an external signal from the Battery Management System or Airbag Control Unit. A dual trigger<\/strong> design adds a self-triggering capability \u2014 it can fire autonomously if internal current sensing detects an overcurrent event, providing a safety layer that doesn’t depend on the BMS signal surviving the crash event intact. Eaton Bussmann’s F40\/F40A series illustrates this architecture, with the dual-trigger variant able to interrupt short-circuit currents exceeding 20 kA across both 400V and 800V architectures.<\/p>\n\n\n\n The most common activation pathway begins with the vehicle’s crash sensors detecting an impact above a defined severity threshold. The Airbag Control Unit (ACU) processes that signal and simultaneously commands two things: airbag deployment and pyro fuse activation. This parallel triggering means the HV circuit is being severed at the same instant the airbags inflate \u2014 both responses happen within a window of a few milliseconds after impact.<\/p>\n\n\n\n Once the ACU sends the ignition current to the pyro fuse initiator, the sequence is mechanical and irreversible: charge ignites, gas expands, piston severs busbar. The total elapsed time from external trigger signal to completed disconnection is under one millisecond in most implementations. The result is a complete open circuit in the main HV path \u2014 the inverter, traction motor, high-voltage contactors<\/a>, onboard charger, and any other HV loads instantly lose their supply. First responders accessing the vehicle no longer face live HV conductors running through crash-deformed body structure.<\/p>\n\n\n\n The Battery Management System provides a second, independent trigger path for non-crash scenarios. The BMS continuously monitors the pack for conditions that could lead to thermal runaway or catastrophic failure: sustained overcurrent, overvoltage conditions, extreme temperature excursions, and cell-level fault states. If those parameters breach defined limits, the BMS can command pyro fuse activation directly \u2014 the same mechanical severance sequence, just initiated by a software fault condition rather than a crash event.<\/p>\n\n\n\n A real-world example of BMS-initiated awareness: Tesla’s BMS_u031 alert, which surfaces on older Model S and Model X vehicles using a self-powered pyro fuse design. That unit contained its own small internal battery to power the initiator circuit. As those batteries aged beyond roughly eight to nine years, the BMS detected that the pyro fuse’s internal power source was approaching end of life and flagged BMS_u031 (“ReplaceSmartFuseSoon”) \u2014 not because the fuse had fired, but because it might fail to fire when needed. Understanding the isolation monitoring system<\/a> alongside BMS-triggered protection gives a clearer picture of how layered the HV safety architecture actually is.<\/p>\n\n\n\n The moment the busbar is severed, significant electrical energy can try to sustain itself across the gap as an arc \u2014 DC arcs are notoriously difficult to extinguish compared to AC because there’s no natural zero-crossing. The non-conductive piston tip isolates the busbar ends physically, while some designs use sand or other arc-quenching media packed around the cut zone to absorb and dissipate the arc energy. This is the distinction between Tesla’s “sand fuse” (SAND_FUSE) and the self-powered hybrid pyro fuse variants \u2014 the arc quenching mechanism differs, which is why the replacement programming step in Tesla’s service procedure requires specifying which fuse type is being installed so the vehicle’s software handles post-replacement configuration correctly.<\/p>\n\n\n\n The pyro fuse sits within a broader set of HV protection devices, each with distinct roles and capabilities. Understanding where each fits helps clarify why all of them are necessary rather than redundant.<\/p>\n\n\n\n High-voltage contactors<\/a> are the switchable relays that connect and disconnect the battery pack under normal operating conditions \u2014 turning HV on when the vehicle powers up, off when it shuts down, and managing the pre-charge sequence that limits inrush current to sensitive electronics. They’re resettable, cycle thousands of times over a vehicle’s life, and respond to commands in roughly 5\u201310 milliseconds. But they depend on low-voltage control circuits to operate; in a severe crash those circuits may be compromised before the contactor can respond. The pyro fuse requires only its initiator circuit and the trigger signal \u2014 a much simpler electrical path that’s more likely to survive crash damage.<\/p>\n\n\n\n The Manual Service Disconnect (MSD) found on many HV battery packs is a human-operated safety measure \u2014 a physical plug or lever that technicians use to isolate the HV system before working on it. It provides zero crash protection because it requires deliberate manual intervention. The hybrid battery system<\/a> design integrates both the MSD and the pyro fuse precisely because they serve completely different use cases: the MSD protects technicians during planned service work, the pyro fuse protects occupants and first responders during unplanned emergencies.<\/p>\n\n\n\n An emerging alternative worth noting is the breaktor<\/strong> \u2014 a resettable device that combines the fast-acting severance of a pyro fuse with the ability to reset itself. Breaxtors are appearing in next-generation 800V architectures as they can replace up to 15 individual BDU components while providing bidirectional short-circuit protection. They don’t yet have the field depth of pyro fuse technology but represent where HV protection engineering is heading.<\/p>\n\n\n\n Location varies by manufacturer and platform, but the common design principle is to place the pyro fuse as close as possible to the HV battery’s positive terminal \u2014 minimising the length of unprotected HV cable between the energy source and the protection device.<\/p>\n\n\n\n On Tesla Model S, 3, X, and Y, the pyro fuse is integrated into the top of the HV battery pack. This means accessing it for replacement requires removing the entire battery assembly \u2014 one reason why pyro fuse replacement on battery pack 1.0 variants is labour-intensive and costs $300\u2013700 or more depending on market and workshop. On pack 2.0 designs, access is somewhat more direct, but the procedure still requires the vehicle on a two-post lift with 12V disconnected and a 2-minute discharge wait before any HV component work begins.<\/p>\n\n\n\n Mercedes-Benz places the pyrotechnic fuse at or near the positive battery terminal on most models, though exact location shifts across the W204, W205, W206, and EQ platforms. BMW integrates the pyro fuse into the battery cable assembly at the positive terminal \u2014 meaning the cable and fuse are replaced as a unit rather than independently. Smart EVs and early Mercedes B-Class Electric Drive use a different mounting position, with the pyro fuse connected into the contactor-relay coil circuit on the low-voltage side rather than directly in the HV busbar path. This architectural variation is one reason why post-activation symptoms can differ between platforms even when the underlying principle is identical. For context on how HV battery thermal management<\/a> affects pack access and service complexity, that background is useful when planning any HV battery-adjacent work.<\/p>\n\n\n\n When a pyro fuse has activated \u2014 whether from a crash or a BMS command \u2014 the vehicle presents a cluster of symptoms that can easily mislead a technician unfamiliar with HV safety system behaviour.<\/p>\n\n\n\n The vehicle will not power up or enter drive mode. Diagnostic scans typically reveal multiple HV communication fault codes simultaneously: powertrain shutdown messages, loss of communication with the inverter or battery module, charging system faults. On MG4 EVs, the dashboard displays “Danger Evacuate Vehicle Safety.” On Mercedes platforms, codes like B284F13 (squib open circuit) or B273513 appear. Tesla surfaces BMS-level faults. On Smart EVs, the fault code indicates pyrofuse tripped with the vehicle unable to exit Park.<\/p>\n\n\n\n The danger here is misdiagnosis. A technician who doesn’t first check for pyro fuse activation may spend time chasing inverter faults, battery module failures, or traction control issues \u2014 all of which can appear simultaneously because the HV isolation intentionally locks out the entire downstream system. The correct first step after any collision with HV fault codes is to verify pyro fuse status before any other diagnostic work. A simple continuity check with an ohmmeter across the fuse terminals will confirm whether it has fired (open circuit) or is intact. The vehicle’s CAN network<\/a> propagates HV isolation status to multiple modules simultaneously, which is why the DTC count after a pyro fuse activation can appear disproportionately large relative to the actual triggering event.<\/p>\n\n\n\n One additional scenario: a pyro fuse can activate without a crash. Severe road impacts, heavy objects falling inside the vehicle onto crash sensors, or BMS fault conditions can all trigger activation. If a vehicle arrives at workshop with no obvious collision damage but fails to power up and shows HV-related fault codes, pyro fuse activation remains on the differential diagnosis list.<\/p>\n\n\n\n \u26a0\ufe0f HIGH VOLTAGE HAZARD \u2014 SAFETY-4 CLASSIFICATION: This section covers a system involving 400V\u2013800V DC. High-voltage direct current is significantly more dangerous than equivalent AC voltages due to the absence of a natural zero-crossing that would extinguish an arc. Contact with live HV components can cause ventricular fibrillation, severe burns, and death. The pyro fuse remains live at battery voltage even after 12V disconnection. All inspection, removal, and replacement procedures require a certified high-voltage technician with manufacturer-specific training, Class 0 (1000V-rated) HV insulating gloves with leather protectors, ESD wrist strap and surface, face protection, and full removal of all metal items from person and pockets.<\/strong><\/p>\n\n\n\n Unlike many electrical components that become safe to handle once 12V power is removed, the pyro fuse sits directly in the HV circuit. Battery voltage is always present at its terminals \u2014 there is no way to make the component safe for handling without physically isolating the HV pack using the manual service disconnect and completing the OEM-specified discharge wait period (typically two minutes minimum). Even then, Hioki precision resistance measurement at each HV joint after installation is mandatory, with acceptable resistance values in the 50\u2013150 \u00b5\u03a9 range that require calibrated micro-ohm measurement equipment not available in general automotive shops.<\/p>\n\n\n\n Beyond hardware, replacement requires OEM diagnostic software to register the new fuse type in the vehicle’s BMS or MCU. On Tesla platforms, the technician must navigate to Service Mode, select the correct fuse type (SELFPOWERED_HYBRIDPYRO or SAND_FUSE as appropriate), write the configuration, and confirm completion before the vehicle will function normally. Without this software step, the vehicle remains non-operational even with a correctly installed physical component. General OBD-II scanners cannot perform this step. For perspective on how the full charging ecosystem is affected when HV is isolated, DC fast charging control<\/a> depends entirely on HV continuity being restored before any charging session can be negotiated.<\/p>\n\n\n\n If your EV or hybrid was in a collision where airbags deployed, do not attempt to restart the vehicle. The HV system has done exactly what it was designed to do \u2014 it has protected you. Recovery to an authorised workshop via flatbed is the correct response; the vehicle is not safe to drive with deployed airbags regardless of whether it could theoretically restart.<\/p>\n\n\n\n If you receive a BMS warning like Tesla’s BMS_u031 with no preceding collision, your vehicle is typically safe to continue driving in the short term \u2014 the alert is predictive, flagging that the pyro fuse’s internal battery is approaching end of life rather than indicating the fuse has already fired. Prompt service by a certified technician is recommended. Replacement cost typically falls between $300 and $700 depending on battery pack generation and the labour required to access it, with some Model S pack 1.0 cases reaching higher due to full pack removal requirements.<\/p>\n\n\n\n No single device provides complete HV safety on its own. Modern EV and hybrid platforms layer multiple, complementary protection systems, with the pyro fuse as the irreversible final backstop.<\/p>\n\n\n\n The High Voltage Interlock Loop (HVIL)<\/a> monitors connector integrity across every HV connector in the system \u2014 if any connector is unseated, the HVIL circuit opens and the BMS commands contactor opening before HV can escape the pack. The isolation monitoring device (IMD) continuously measures insulation resistance between HV circuits and vehicle chassis; if insulation degrades below a safe threshold, the IMD triggers a fault response. HV contactors manage routine connection and disconnection of the pack. The pyro fuse sits behind all of these \u2014 it activates when conditions are too severe or too fast for the softer protection layers to respond adequately.<\/p>\n\n\n\n The downstream components that the pyro fuse protects \u2014 traction motors<\/a>, motor controllers, e-axle assemblies<\/a>, and the entire power electronics chain \u2014 all represent significant replacement cost and complexity. Protecting them from fault energy propagation is a secondary benefit of the pyro fuse beyond the primary occupant and first-responder safety function.<\/p>\n\n\n\n The design intent is worth stating clearly: when the pyro fuse fires, it is not a failure. It is a success. The system performed exactly as engineered, using an irreversible intervention to prevent a potentially catastrophic outcome. Understanding that distinction changes how you approach post-activation diagnosis \u2014 the starting point is not “what went wrong with the electrical system” but “what triggered the safety system, and has that underlying condition been resolved before HV is restored.”<\/p>\n\n\n\n The pyro fuse is the final, irreversible layer in a vehicle’s HV safety architecture \u2014 a component you hope never activates, but one whose correct operation can be the difference between a survivable collision and a catastrophic electrical fire. When it fires, the system has done its job. The practical implications for owners and technicians are straightforward: post-activation HV work is certified-technician territory, software configuration is mandatory alongside physical replacement, and misidentifying an activated pyro fuse as an electrical fault wastes time while leaving the root cause unaddressed. For model-specific procedures, part numbers, and torque specifications, the OEM service manual remains the authoritative reference. How EV charging ports<\/a> and the full HV power path work in normal operation provides useful context for understanding everything this small but critical device is designed to protect.<\/p>\n\n\n\n Electric and hybrid vehicles use a pyro fuse \u2014 a single-use pyrotechnic safety device \u2014 to cut off the high-voltage battery in emergencies. Whether you’ve just heard the term for the first time or you’re trying to understand why your EV won’t start after a minor collision, the answers below cover what the pyro fuse does, when it activates, and what to do about it.<\/p>\n\n\n\n A pyro fuse permanently severs the main high-voltage circuit in an EV or hybrid when crash sensors or the Battery Management System detect a critical event. It activates in under one millisecond, cannot be reset, and must be replaced by a certified high-voltage technician. If your vehicle won’t power up after a collision and shows multiple HV fault codes, a triggered pyro fuse is the most likely cause \u2014 not an underlying electrical failure.<\/p>\n\n\n\n A pyro fuse is a one-shot high-voltage safety device that permanently disconnects the main HV circuit between the battery pack and the rest of the vehicle \u2014 the inverter, traction motor, onboard charger, and all HV loads \u2014 when it receives a trigger signal. It uses a small pyrotechnic charge (similar in principle to an airbag inflator) to drive a piston through the main HV busbar, creating a permanent open circuit in under one millisecond.<\/p>\n\n\n\n The purpose is straightforward: in a crash or electrical fault, a live high-voltage system running through deformed body structure creates serious risk of electrocution and fire for occupants and emergency responders. The pyro fuse removes that risk faster than any mechanical relay or contactor could react. Understanding how it fits into the broader hybrid battery system<\/a> helps explain why this level of protection is necessary at 400\u2013800V DC.<\/p>\n\n\n\n There are two primary trigger pathways. The most common is a crash event: when the vehicle’s crash sensors detect an impact above a defined severity threshold, the Airbag Control Unit (ACU) sends a simultaneous command to deploy the airbags and fire the pyro fuse. Both happen within milliseconds of each other.<\/p>\n\n\n\n The second pathway is the Battery Management System. The BMS monitors the pack continuously for overcurrent, overvoltage, and thermal fault conditions. If any parameter breaches a critical threshold \u2014 including the early signs of thermal runaway \u2014 the BMS can command pyro fuse activation independently of any crash event. Some designs also include a self-triggering capability, where the fuse fires autonomously if its internal current sensing detects a catastrophic overcurrent even without a BMS or ACU signal. The isolation monitoring device<\/a> works alongside the BMS as a complementary fault detection layer in the same HV safety architecture.<\/p>\n\n\n\n No. A pyro fuse is a single-use device by design. Once the pyrotechnic charge fires and the piston severs the busbar, the conductor is permanently cut and the enclosure is sealed around the damage. There is no mechanical reset, no replaceable element, and no way to restore the original circuit path. The only resolution is full component replacement with a new pyro fuse unit.<\/p>\n\n\n\n This is intentional \u2014 a safety device that could be reset without proper inspection and diagnosis would undermine the entire purpose of the system. Compare this to HV contactors<\/a>, which are resettable relays designed to cycle thousands of times over the vehicle’s life, or conventional automotive fuses<\/a> where you simply swap the blown element. The pyro fuse’s irreversibility is a feature, not a limitation.<\/p>\n\n\n\n Post-activation symptoms closely resemble a major electrical system failure, which is one of the main diagnostic pitfalls technicians face. Typical signs include: the vehicle will not power up or enter drive mode; multiple HV-related fault codes appear on a diagnostic scan (powertrain shutdown, loss of communication with inverter or battery modules, charging system faults); charging fails to initiate; and in some vehicles, an explicit dashboard warning such as “Danger Evacuate Vehicle Safety” is displayed.<\/p>\n\n\n\n Platform-specific DTC examples: Mercedes-Benz shows B284F13 (squib open circuit) or B273513; Tesla surfaces BMS-level HV faults; Smart EVs flag pyrofuse tripped with the vehicle locked out of Park exit. The vehicle’s CAN network<\/a> propagates the HV isolation status to multiple modules simultaneously, so the fault code count is often much higher than the single underlying trigger event would suggest. Always check for pyro fuse activation first after any collision before chasing individual fault codes.<\/p>\n\n\n\n \u26a0\ufe0f HIGH VOLTAGE HAZARD \u2014 SAFETY-4: The pyro fuse is integrated directly into the HV circuit. Battery voltage (400\u2013800V DC) is present at the fuse terminals even after 12V disconnection. Contact with live HV components can cause severe burns, cardiac arrest, and death. This procedure requires a certified high-voltage technician with Class 0 (1000V-rated) HV insulating gloves, leather protectors, ESD equipment, face protection, and OEM diagnostic software.<\/strong><\/p>\n\n\n\n Pyro fuse replacement is not appropriate for DIY. Beyond the live HV hazard, the procedure on most platforms requires full or partial battery pack removal, micro-ohm resistance testing at HV joints using calibrated Hioki equipment (with tolerances in the 50\u2013150 \u00b5\u03a9 range), and a mandatory software configuration step to register the fuse type in the vehicle’s BMS or MCU. On Tesla vehicles, this means navigating to Service Mode and writing the correct fuse type (SELFPOWERED_HYBRIDPYRO or SAND_FUSE) before the vehicle will operate. A general OBD-II scanner cannot perform this step. Without the software registration, the vehicle remains non-operational even with a correctly installed physical component.<\/p>\n\n\n\n The HVIL system<\/a> and other HV safety interlocks must also be verified as intact before HV is restored \u2014 something that requires OEM tooling and training to confirm properly.<\/p>\n\n\n\n The fuse component itself is relatively inexpensive \u2014 typically in the $100\u2013175 range for common Tesla variants. Total replacement cost, including labour, generally falls between $300 and $700. The wide range reflects the significant variation in labour required across platforms and battery pack generations.<\/p>\n\n\n\n On vehicles where the pyro fuse is accessible without major disassembly (some Mercedes and BMW applications), the labour component is modest. On Tesla Model S and X with battery pack 1.0, the fuse is located on top of the HV pack and requires complete battery removal \u2014 a labour-intensive process that can push total cost higher. Battery pack 2.0 designs are more accessible but still require the vehicle on a lift with the full HV disablement procedure completed. For context on how the battery thermal management system<\/a> affects pack access and disassembly sequence, that background informs why some platforms are significantly more labour-intensive than others.<\/p>\n\n\n\n Yes. While crash activation is the most commonly discussed scenario, there are several non-collision triggers. The Battery Management System can command activation if it detects a serious electrical fault \u2014 sustained overcurrent, extreme overvoltage, or early thermal runaway indicators. Some vehicles have experienced activation from unusually severe road impacts (large potholes, speed bumps at high speed) that generate enough deceleration force to cross the crash sensor threshold without visible collision damage.<\/p>\n\n\n\n Tesla’s BMS_u031 alert represents a different, predictive non-crash scenario: it flags that an aging self-powered pyro fuse’s internal battery is approaching end of life, meaning the fuse hasn’t fired but may fail to fire when needed. This alert requires prompt replacement but does not indicate the vehicle is unsafe to drive in the short term. If a vehicle arrives with no collision evidence but presents HV fault codes and refuses to power up, pyro fuse activation should be near the top of the diagnostic list alongside other HV isolation faults flagged by the isolation monitoring system<\/a>.<\/p>\n\n\n\n They serve completely different purposes despite both being HV isolation devices. The Manual Service Disconnect (MSD) is a physical plug or lever \u2014 usually orange \u2014 that technicians remove before working on the HV system. It requires deliberate human action, takes several seconds to operate, and can be reinstalled after work is complete. It provides zero crash protection because it requires someone to manually engage it.<\/p>\n\n\n\n The pyro fuse is automatic, signal-triggered, completes in under one millisecond, and is irreversible. It protects against crash and fault scenarios where there is no time or opportunity for human intervention. The two devices complement each other: the MSD enables safe planned service work on a powered-down system; the pyro fuse handles unplanned emergency disconnection. Both are part of a layered safety architecture alongside HV contactors<\/a> and the e-axle<\/a> and drivetrain components they collectively protect. For model-specific locations, part numbers, and replacement procedures for either device, the OEM service manual for your vehicle is the authoritative reference.<\/p>\n\r\n\t\t\tInside a Pyro Fuse: Key Components<\/h2>\n\n\n\n
How the Pyro Fuse Activates<\/h2>\n\n\n\n
Crash-Triggered Activation<\/h3>\n\n\n\n
BMS-Triggered Activation<\/h3>\n\n\n\n
Arc Suppression After Severance<\/h3>\n\n\n\n
Pyro Fuse vs. Other HV Protection Devices<\/h2>\n\n\n\n
Where the Pyro Fuse Lives in the Vehicle<\/h2>\n\n\n\n
Post-Activation: What Technicians Observe<\/h2>\n\n\n\n
\u26a0\ufe0f High Voltage Safety \u2014 Service Requirements (SAFETY-4)<\/h2>\n\n\n\n
Why This Is Not a DIY Procedure<\/h3>\n\n\n\n
What Owners Should Know<\/h3>\n\n\n\n
The Pyro Fuse Within the Broader HV Safety Architecture<\/h2>\n\n\n\n
Conclusion<\/h2>\n\n\n\n
Pyro Fuse FAQ: Common Questions Answered<\/h1>\n\n\n\n
Quick Answer<\/h3>\n\n\n\n
What does a pyro fuse do in an EV or hybrid?<\/h2>\n\n\n\n
What triggers a pyro fuse to activate?<\/h2>\n\n\n\n
Can a pyro fuse be reset after it fires?<\/h2>\n\n\n\n
What are the symptoms of a triggered pyro fuse?<\/h2>\n\n\n\n
Is pyro fuse replacement a DIY job?<\/h2>\n\n\n\n
How much does pyro fuse replacement cost?<\/h2>\n\n\n\n
Can a pyro fuse activate without a crash?<\/h2>\n\n\n\n
What’s the difference between a pyro fuse and a manual service disconnect?<\/h2>\n\n\n\n
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