Motorola Moto G84 5G Faces USB‑OTG Issues Due to Faulty VBUS Power Supply

Motorola’s mid‑range Moto G84 5G was lauded for its Snapdragon 695 chipset, 12 GB of RAM and a crisp 6.5‑inch P‑OLED display, but the device’s USB‑OTG functionality has turned into a cautionary tale about hardware tolerances. After upgrading from Android 13 to 15, Goughlui noticed that a USB‑C thermal camera that had previously worked “perfectly” would no longer be recognized, even after cleaning the port, swapping cables and trying an extension. The same camera plugged into a different phone or a laptop behaved normally, and other peripherals sometimes connected to the G84 5G, albeit unreliably. The inconsistency prompted a deeper dive into the phone’s power delivery on the VBUS line, the rail that supplies 5 V to any attached USB device.

Using a Fnirsi FNB58 test load, Goughlui measured the VBUS voltage directly at the connector and found a steady 5.50 V—well above the USB‑C specification’s 4.75–5.25 V window. The over‑voltage persisted across multiple plug‑in cycles, suggesting it was not a transient fault but a systematic mis‑regulation. When the CC termination was removed, the port stopped supplying power, indicating that the load‑switch MOSFET itself was still functional; the problem lay in the regulation stage that set the VBUS level. Despite the anomaly, the phone continued to charge at TurboPower speeds and transferred data without issue, underscoring how the over‑voltage selectively crippled OTG host mode while leaving sink mode untouched.

The root cause appears to be a faulty VBUS power supply rather than software. Goughlui points out that modern Android devices lock their bootloaders and enforce signed firmware, making it impossible to roll back to a pre‑OTG‑break version of the OS. This hardware‑level defect therefore survives OS updates, and the timing of the Android 15 rollout may be coincidental rather than causal. The situation mirrors scattered user reports on forums where the Moto G84 5G “simply won’t detect any USB‑OTG device,” a symptom now explainable by the 5.50 V rail that exceeds the tolerance of many peripherals.

Motorola has not issued an official statement, and no repair program has been announced. For power‑hungry accessories—thermal cameras, external SSDs, or USB‑C dongles—the extra 0.25 V can push the device’s internal protection circuits into shutdown, resulting in the intermittent or complete loss of connectivity that Goughlui observed. The phone’s fast‑charging circuitry remains unaffected because it operates under a different control loop that tolerates higher voltages, which explains why the device still “retains perfect fast (TurboPower) and standard charging functionality.” In short, the hardware is split: one side works, the other is throttled by an out‑of‑spec power rail.

For owners of the Moto G84 5G, the practical takeaway is to test any USB‑OTG peripheral with a known‑good phone before assuming the device is at fault. If the accessory works elsewhere, the G84 5G is likely the culprit, and the only reliable workaround is to avoid using OTG mode until Motorola releases a hardware revision or a firmware fix that reinspects the VBUS regulation. As Goughlui’s investigation shows, the problem is not a software toggle or a missing privacy switch—it is a hardware design oversight that silently violates USB‑C voltage limits, turning a promising mid‑range phone into a device that “sometimes works” when it comes to USB‑OTG.