My Chevy Silverado EV says "Service High Voltage System." What does that mean?

Short answer: A 'Service High Voltage System' warning on a Silverado EV is often cleared by a 12-volt reset, which owners say GM recommends for certain codes. Use the procedure in your owner's manual and never touch orange cables. Press OnStar for a diagnostic. If the warning comes back or range drops to 0%, book the dealer. Owners had battery control software updated and parts like coolant valves, a grille shutter and even a main battery replaced under warranty.

Symptom: A 'Service High Voltage System' message, sometimes with 0% range shown, after parking, rain or a car wash.

What to check first

1. Request an OnStar diagnostic and save the report.
2. If you're comfortable, do the 12-volt reset in the owner's manual.
3. Note whether it follows rain or a car wash.
4. If it comes back, book the dealer and ask for the codes and parts in writing.
5. Run your VIN at nhtsa.gov/recalls for 24V320000.

Likely causes

1. 12-volt battery or electrical glitch. Almost every modern car, including EVs, has a small 12-volt battery that powers the computers, locks and screens. When it's weak or isn't being recharged, the car can show a pile of unrelated warnings or refuse to go into gear, even with a full main battery.
2. Battery control module software. Owners had the battery control module updated at the dealer.
3. Hardware such as a coolant valve, grille shutter or the main battery. Owners reported coolant valves, a grille shutter, a telematics part and in one case a main battery being replaced.

What it usually costs

Owners' repairs were under warranty and they didn't post prices.

Is it safe to keep driving?

If the truck shows 0% or won't drive, call Chevy roadside. If it drives normally, owners drove to the dealer. If you smell burning or see smoke, get out and call 911.

DIY or shop?

The 12-volt reset is DIY. High-voltage diagnosis and repairs are dealer work. An EV's high-voltage system can stay live with the car off. Leave the orange cables, the big battery and the drive unit to a trained EV technician.

Recalls, bulletins and complaints in plain words

• Related recall: NHTSA lists 24V320000 for some 2024 Silverado EVs: wires in the rear drive motor may not be insulated well enough, which can cause a loss of drive power. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 7 keyword-matched complaints for Chevrolet Silverado EV 2024–2025 (of 40 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-31; keywords: high voltage, 12 v, battery, charg, won t start, dead, propulsion) (NHTSA returned no data for 4 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Kiss of Death - Service High Voltage System on Reddit r/SilveradoEV, a 2024 Silverado EV RST owner at about 5,500 miles got the warning 300 miles from home after charging overnight on a 110-volt outlet. Another owner had the same thing right after buying, drove home and left the 12-volt disconnected for a while, and a commenter said GM recommends a 12-volt disconnect when certain high-voltage battery codes are present.
• In "Service High Voltage" - won't start 0% on Reddit r/SilveradoEV, a 2025 Silverado EV at about 10,000 km showed 0% range and 'Service High Voltage System' after stopping at the beach, then worked normally two hours later. Owners described a 12-volt reset of disconnecting the negative cable and a green connector for about 5 minutes, and suggested an OnStar diagnostic.
• In Service high voltage system on Reddit r/SilveradoEV, owners compared Service High Voltage fixes: battery control module updates, one main battery replaced in about a month, a coolant valve, a grille shutter on a 2026, and a telematics part that took three weeks. Some noticed it after car washes or rain.

Quick tip

A reset is fine once. If it keeps happening after rain or washes, tell the dealer that pattern. It helps them find a leak or a bad valve faster.

Vehicle focus: Chevrolet Silverado EV, 2024-2025.

Safety / mechanic note

High-voltage faults are a safety item. Verify with a mechanic.