Why do my semi-truck batteries die overnight when the truck sits
Parasitic draws from aftermarket electronics, a failing alternator, or sulfated batteries are the most common reasons semi-truck batteries die overnight. Start by…
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Heavy-Duty Vehicles & Fleet
Practical, step-by-step fixes for heavy-duty vehicles & fleet problems — 62 published so far.
Why do my truck batteries die overnight even after replacing them
Your truck batteries drain overnight because of a parasitic draw — something stays powered on after shutdown. Common culprits: faulty alternator diodes,…
See the fixwhy does my 2020 Freightliner Cascadia alternator not charge at idle
Your 2020 Freightliner Cascadia's alternator likely isn't charging at idle because the engine RPM is too low to excite the alternator's voltage…
See the fixWhy does my 2021 Freightliner Cascadia burn 15% more fuel after the last ECM update?
The ECM update likely changed fuel-map calibration, injection timing, or torque curves, making the engine run richer or at higher RPMs. Dealers…
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Why does my 2022 Freightliner Cascadia get 1.5 MPG worse after the last DPF cleaning
A forced DPF regeneration or cleaning can leave the engine running richer temporarily while the ECU relearns soot load, and a clogged…
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Why does my 2022 Freightliner Cascadia keep showing a 'low NOx conversion efficiency' fault after every regen?
A 'low NOx conversion efficiency' fault after regen usually means the SCR catalyst is degraded, the DEF doser is clogged, or the…
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Why does my 2023 Ford E-Transit lose 40 miles of range overnight when parked unplugged
Your Ford E-Transit loses range overnight because the battery thermal management system draws power to keep the pack at optimal temperature, and…
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Why does my 2023 Freightliner eCascadia lose 40% range in winter?
Cold temperatures reduce battery efficiency and increase heating demand, cutting your eCascadia's range by 30-40%. Precondition the cab while plugged in, keep…
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Why does my Class 8 truck's DEF system keep throwing a fault code?
A recurring DEF fault code usually means the diesel exhaust fluid is contaminated, the dosing valve is clogged, or the NOx sensor…
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Why does my Class 8 truck's DEF system keep triggering a derate code?
A recurring DEF derate code usually means the selective catalytic reduction system detects poor urea quality, a clogged dosing valve, or a…
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Why does my diesel truck keep going into limp mode with DEF/SCR system faults?
Your diesel truck enters limp mode because the DEF/SCR system detects a fault — usually bad DEF fluid, a clogged doser, failed…
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Why does my diesel truck lose power and blow black smoke when climbing hills?
Black smoke and power loss on hills usually mean your diesel engine is getting too much fuel or not enough air —…
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