Who this is for: CDL drivers, owner-operators, fleet managers, new CDL applicants
What Is an ELD? Electronic Logging Device Overview
An Electronic Logging Device (ELD) automatically records a commercial driver's hours of service data by connecting to the vehicle's engine control module. ELDs replaced paper log books under the FMCSA ELD mandate. All devices must be self-certified and listed on the FMCSA ELD registered list.
Important Notice
ELD rules and the FMCSA ELD registered list change over time. Always verify current requirements at fmcsa.dot.gov and confirm a device is on the current registered list before purchasing.
What an ELD does
An ELD connects directly to the vehicle's engine control module (ECM) and automatically records engine power status, vehicle motion, miles driven, and engine hours. When the vehicle moves, the ELD begins recording driving time automatically — the driver doesn't have to manually log that the truck is moving. The driver does manually record duty status changes: switching from driving to on-duty not driving, going off duty, or entering the sleeper berth. ELDs must capture 13 required data elements under the technical specifications at 49 CFR Part 395 Appendix A, including location coordinates at each duty status change, and must store records for at least 8 days on the device.
What ELDs replaced
Before ELDs, drivers required to track HOS maintained paper Records of Duty Status (RODS), commonly called log books. Paper RODS required drivers to manually draw the grid lines representing their duty status changes. An intermediate device — the Automatic On-Board Recording Device (AOBRD) — was grandfathered for carriers already using it, but AOBRD authorization ended December 16, 2019. After that date, all carriers required to maintain RODS needed ELDs unless an exemption applied. ELDs provide more accurate and tamper-resistant records because they draw data from the vehicle ECM rather than relying on the driver to fill in the grid correctly.
How to find a compliant ELD
ELD manufacturers self-certify their devices as meeting FMCSA technical specifications and submit them to FMCSA's registered ELD list. Before purchasing or leasing any ELD, verify the specific device (including model number) appears on the current list at fmcsa.dot.gov. The list changes — devices are added as new products are submitted and removed when a manufacturer withdraws certification or falls out of compliance. Being on the list means the manufacturer has declared compliance; FMCSA does not independently test or certify ELDs. A device that was on the list when purchased but has since been removed is a compliance problem.
How ELD data is transferred at inspections
When an inspector requests ELD data at a roadside inspection, the driver must be able to display the data on the ELD screen or transfer it electronically. FMCSA-compliant ELDs support at least two transfer methods: local wireless (Bluetooth or WiFi) and USB. Some also support telematics-based web service transfer. The driver must be able to produce at least the current 24-hour period and the previous 7 days of records. Inspectors transfer data to their enforcement devices using the applicable transfer method. A driver who cannot produce records — because the ELD is malfunctioning or they don't know how to use the transfer function — faces a potential OOS order for HOS record unavailability.
What ELD data is used for
ELD records are inspected at roadside weigh stations and during compliance reviews. The data shows the driver's current HOS status, whether any limits have been exceeded, and location history for each duty status change. Carriers access ELD data through the provider's back-office portal for compliance monitoring, driver coaching, and internal audit. FMCSA and state enforcement agencies can access historical records during compliance reviews. The carrier's motor carrier portal access typically covers a longer retention window than the 8-day minimum on the device itself.
ELD vs. GPS tracker
An ELD is not the same as a GPS tracker, though many ELD products include GPS functionality as a combined feature. The legal requirement is the ELD function — the ECM connection that records engine status and driving time. GPS location tracking is separately useful for fleet management but is not itself what makes a device an ELD. Some ELD solutions are hardware devices hardwired into the cab; others are software applications on a tablet or smartphone paired with a small Bluetooth or cable adapter that connects to the diagnostic port. Both can be compliant if the complete system is on the FMCSA registered list.
Frequently Asked Questions
Who can see my ELD data?
Roadside inspectors may view ELD data during inspections. Your carrier (or motor carrier if you are leased to one) has access to your ELD records through the provider's back-office system. FMCSA and state enforcement agencies can access data during compliance reviews. You have the right to see your own ELD records.
Can an ELD be used for personal conveyance?
Yes. ELDs have a "personal conveyance" (PC) duty status that records use of the truck for personal purposes as off-duty time. FMCSA allows limited personal conveyance when the driver is genuinely off duty. The ELD continues to track location during PC, and carriers may set their own policies on PC use.
What happens if my ELD malfunctions?
If an ELD malfunctions, the driver must note the malfunction and contact the carrier immediately. The driver must keep paper logs for up to 8 days while the malfunction is resolved. The carrier must correct the issue within 8 days or obtain an extension from FMCSA. Driving with a known ELD malfunction beyond the permitted period is a violation.