When a serious trucking crash happens on South Carolina roads—from I95 and I26 to rural two lanes—the most powerful evidence may be inside the tractor itself: the engine control module (ECM) or event data recorder (EDR). Used properly, this data can corroborate physical evidence, clarify timelines, and rebut inaccurate narratives.
Below is a practical guide tailored to South Carolina law and procedure.
Passenger vehicles often store crash data in a dedicated EDR integrated with the airbag control module. Heavy commercial vehicles are different. Most tractors store operational snapshots in the ECM (sometimes called a heavy-vehicle EDR or HVEDR). Many fleets also run Electronic Logging Devices (ELDs) and separate telematics platforms. These systems are distinct:
Key takeaway: Do not assume tractor data looks like passenger-car crash data. Identify and pursue all three sources—ECM, ELD, and telematics/cameras.
HVEDRs typically record vehicle speed, brake usage, and diagnostic trouble codes. More specifically:
In South Carolina, an injured person can recover as long as their fault does not exceed 50%. Objective truck data often reduces disputed fault percentages by showing excess speed, delayed braking, or non-compliance—directly impacting apportionment and damages.
Example: If a jury finds the plaintiff 20% at fault and the truck driver 80% at fault on $500,000 damages, the net recovery is $400,000. Without objective data, the defense may succeed in pushing the plaintiff’s share above 50%, eliminating recovery entirely.
Act fast. Some ECM records are overwritten by later operation; telematics vendors may purge data under short retention policies.
Send a comprehensive preservation letter (litigation hold) to the motor carrier and its insurer, identifying:
Follow with Rule 45 subpoenas and, once filed, Rule 34 requests specifying native formats/metadata. Where appropriate, seek early protective orders/TROs to secure the truck and modules for inspection and imaging.
Wrongful death, medical malpractice, and other categories have additional rules—evaluate case-specific deadlines immediately.
South Carolina minimum auto limits: $25,000/$50,000 bodily injury and $25,000 property damage (25/50/25). Commercial motor carriers in interstate commerce typically carry much higher liability limits (often $750,000+; more for certain cargo/hazmat), so proving liability with hard data can materially affect settlement value.
Window
Practical Risk
Recommended Action
0–7 days
Truck towed/repaired; ECM snapshots overwritten by subsequent operation; short vendor retention for camera/telematics
Issue preservation letters and insurer notice immediately; request the truck be taken out of service until modules are imaged; ask the carrier to suspend autodeletion.
8–30 days
Some fleets auto-purge certain telematics/camera clips; ELD malfunction remediation deadlines can be misread
Follow up on the hold; request native exports from ELD/telematics; if resistance, file early suit and move for a preservation order.
≤ 6 months
Hours of service supporting documents must be retained by carriers for at least 6 months; delays risk loss of complementary HOS evidence
Serve Rule 34 requests specifying native formats/metadata; seek Rule 30(b)(6) on data systems and retention.
Up to 3 years
FMCSA accident register and required accident reports must be kept 3 years, but do not include ECM/EDR content
Request the register and all required accident reports; do not rely on this to capture ECM/EDR/telematics.
Heavy-truck data is manufacturer-specific. Retain experts who:
☐ Send a detailed preservation letter within days
☐ Seek consensual imaging or move quickly for a court order
☐ Demand native ECM/ELD/telematics exports and configuration files
☐ Notice a 30(b)(6) deposition on data systems and retention
☐ Establish airtight chain of custody and expert foundations
☐ Calendar the 3-year general PI SOL and any 2 or 3-year TCA deadlines
Objective truck data—properly preserved, extracted, and explained—can be outcome-determinative under South Carolina’s modified comparative negligence framework. Move fast, be specific about the sources you want, and build a record that survives admissibility challenges and persuades adjusters and juries alike.
For help preserving and using ECM/EDR, ELD, and telematics evidence in a South Carolina trucking case, contact Proffitt & Cox.
When a serious trucking crash happens on South Carolina roads—from I95 and I26 to rural two lanes—the most powerful evidence may be inside the tractor
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