Who it’s for: Texans injured in car or 18-wheeler crashes, families pursuing wrongful death claims, and attorneys/adjusters evaluating liability.
When to read: In the first days after a crash—before crucial electronic data is overwritten.
What you’ll learn: What each data source is (EDR/ECM, telematics, ELD), what it records, typical purge risks, Texas preservation tools, and fast steps to secure data (or sanctions if it’s destroyed).
Why these “black boxes” make or break your case
Modern vehicles generate an electronic trail that can answer the questions juries care about: speed, braking, throttle, hard-brake events, hours-of-service, and location history. But the data lives in different places, is controlled by different actors, and can disappear on different timelines. If you move fast, you can lock it down. If you don’t, it can be gone—or you may be litigating spoliation.
Quick definitions
- EDR (Event Data Recorder) / ECM (Engine Control Module):
Hardware in the vehicle (light vehicles = EDR; heavy trucks often refer to ECM). Think on-board snapshot of a crash or certain “trigger” events. Usually retrieved via a forensic download from the vehicle. - Telematics (e.g., dashcams + GPS + fleet platforms):
Cloud-based services used by fleets. Think ongoing breadcrumb trail—GPS pings, speed, harsh events, sometimes inward/outward-facing video. Controlled by the motor carrier (and its vendor). - ELD (Electronic Logging Device):
Federally mandated for most interstate CMV drivers; it tracks hours-of-service. Think compliance logs with engine hours, miles, duty-status changes, and location stamps. Retention is governed by federal rules (more below). (FMCSA)
What each box stores (and who controls it)
| Source | Typical Contents | Who Controls It | How It’s Retrieved |
|---|---|---|---|
| EDR/ECM (on-vehicle) | Pre-crash speed, throttle %, brake on/off, seatbelt (light vehicles), delta-V; heavy-truck ECMs may include last-stop records, hard-brake snapshots, fault codes | Owner of the vehicle; in trucking, the motor carrier (or its insurer) | Physical access + forensic imaging by a qualified expert |
| Telematics (cloud) | GPS tracks, harsh braking/accel, speed, geofences, camera video (road & driver), alerts, sometimes maintenance + driver behavior scores | Motor carrier + vendor (Samsara, Motive, Geotab, Verizon Connect, etc.) | Subpoena to carrier and (if needed) vendor; export of CSV/MP4, or platform share |
| ELD (logs) | Duty status changes (on/off/drive/sleeper), date/time, location, engine hours, miles, driver/vehicle IDs; edits & annotations | Motor carrier | Subpoena/request to carrier for certified RODS + data export; audit trail shows edits (FMCSA) |
Note: Data schemas vary by make/model/vendor. Even when two trucks look identical, their ECM/telematics fields and sampling rates can differ.
How fast does it get purged?
- EDR/ECM:
Not usually time-purged. Instead, it’s event-limited. A crash “locks” a snapshot; a subsequent qualifying event may overwrite limited-slot memories. Some heavy-truck ECMs also keep circular buffers for “hard-brake” or “last stop” events that overwrite with new events. Service resets or repairs can also wipe data. - Telematics:
Policy-driven. Many fleets set retention windows anywhere from 30 days to 12+ months for standard GPS/video. Some video platforms save only event-flagged clips unless an admin bookmarks or downloads the full segment. Assume short windows for high-volume video unless preserved. - ELD:
Federal rule: carriers must retain RODS and supporting documents for 6 months and keep a six-month backup on a separate device. Drivers must keep the last 7 days available in-cab. (FMCSA, eCFR)
Bottom line: Treat telematics video as the most perishable (days–weeks). Treat EDR/ECM as overwrite-limited (one new trigger can replace the only slot). Treat ELD as regulated (6-month retention), but request ASAP because carriers transition systems and staff, and “available” ≠ “easy to produce.”
Texas preservation & sanctions—your leverage
- When duty to preserve attaches: In Texas, a party’s duty to preserve evidence arises when it knows or reasonably should know there is a substantial chance a claim will be filed.
- Spoliation framework: The Texas Supreme Court in Brookshire Bros., Ltd. v. Aldridge, 438 S.W.3d 9 (Tex. 2014) made clear: the trial judge decides spoliation; severe remedies (like an adverse-inference instruction) are reserved for intentional destruction or where loss irreparably prevents a fair trial. Lesser, proportionate remedies address negligent loss and prejudice.
Use the tools:
- Pre-suit: Send a litigation-hold/spoliation letter immediately. Consider a Rule 202 petition (pre-suit deposition) to identify vendors/policies and lock down retention settings.
- In suit: Deploy TRCP 196.7 (entry onto property/vehicle for inspection, imaging), TRCP 196 (requests for production), and TRCP 205 (non-party subpoenas) to telematics vendors.
- If data is lost: Seek proportionate sanctions tied to the specific prejudice (cost-shifting, evidentiary presumptions short of adverse inference, or—if intentional—an instruction).
72-hour action plan (plaintiff’s side)
Day 0–2 (now):
- Send targeted preservation letters to: motor carrier, driver, insurer, telematics vendor, and any third-party camera custodian (e.g., shipper yard, warehouse, retail lot). Spell out EDR/ECM extraction, ELD/RODS + audit trail, telematics raw files (GPS/accelerometer), and video (with precise time ranges/time zone).
- Request a vehicle hold: No repairs, no battery disconnect, no diagnostics that could alter memory, and no attempts to download without notice.
- Identify the platform(s): Ask the carrier which ELD/telematics vendor(s) and camera model(s) were active; demand admin-level export and retention extension.
Day 3–10:
4. File for inspection/imaging (TRCP 196.7) and set a neutral protocol:
- Qualified expert, read-only adapters, hash-verified images, full chain of custody.
- For telematics/video: native CSV/JSON and original MP4 with metadata (timestamps, GPS sampling rates, camera FOV).
- Subpoena vendors (TRCP 205) for configuration logs, retention policies, and user activity (who viewed/downloaded/edited clips).
- Calendar ELD six-month window and set reminders for rolling productions—don’t wait until month five. (FMCSA)
Practical pitfalls (and how we avoid them)
- Wrong clock / wrong map: Timestamps may be in UTC or a different time zone. We reconcile with cell-tower records, CAD/911 timestamps, and vehicle infotainment time when available.
- “We don’t have it”—but they do: Carriers often say only “event-flagged” clips exist; we demand continuous footage segments straddling the crash (e.g., –5 to +10 minutes) and storage logs proving unavailability.
- One-slot ECM overwrites: We push for rapid immobilization and court-ordered inspection to avoid a second “trigger” event overwriting the only snapshot.
- ELD edits: We request the edit/audit trail to expose log tampering, unassigned-drive time reassignments, and co-driver anomalies.
Example asks you should copy into your preservation letter
- EDR/ECM: “Preserve and make available for neutral forensic imaging all EDR/ECM modules, including but not limited to powertrain, braking, and airbag control units. Do not perform repairs, diagnostics, firmware updates, or battery disconnects pending imaging.”
- Telematics: “Preserve and export in native format all GPS/accelerometer data, harsh-event flags, continuous and event-flagged video from T–10 min to T+20 min, driver-facing and road-facing, plus retention settings and admin logs.”
- ELD: “Produce RODS for 90 days pre-crash to 30 days post-crash, plus edit/audit history, malfunctions/diagnostics, unassigned drive time, and driver/carrier annotations.”
When the other side stonewalls
If the motor carrier drags its feet or “can’t find” data it had a duty to preserve, we move for sanctions tailored to the prejudice—fees, exclusion of defense experts who relied on missing data, or (for intentional deletion) an adverse-inference instruction under Brookshire principles. We pair that with independent sources—911 audio/CAD, nearby business cams, vehicle infotainment, and smartphone telemetry—to rebuild the timeline.
Related reads on our site
- Differences Between Car and Truck Accident Claims (why truck cases hinge on logs/data) → ryanorsattilaw.com/differences-between-car-and-truck-accident-claims/ (Ryan Orsatti Law)
- San Antonio Car Accident Lawyer (how we preserve and prove your claim) → ryanorsattilaw.com/san-antonio-car-accident-lawyer/ (Ryan Orsatti Law)
- Rideshare Requirements in Texas (platform rules & data) → ryanorsattilaw.com/understanding-vehicle-and-driver-requirements-for-uber-and-lyft-in-texas/ (Ryan Orsatti Law)
Authoritative source (ELD retention)
- FMCSA, General Information about the ELD Rule (RODS retention & backup = 6 months) — a must-know in every trucking case. (FMCSA)
Local help—move fast, preserve more
Ryan Orsatti Law
4634 De Zavala Road │ San Antonio, TX 78249
T. 210.525.1200
Free, same-day evidence-preservation plan: If you call us within days of a serious crash, we’ll draft and send tailored hold letters, pursue rapid orders to inspect the vehicles, and lock down telematics/ELD before it rolls off the server. We handle the experts, the downloads, and the subpoenas—so you can focus on getting well.
Not sure what data exists? We’ll identify the exact vendor stack, module list, and retention settings, then secure the right exports. The sooner you act, the more truth we can save.