Remote tamper detection. At least some of the example embodiments are methods including: tracking location of an asset by an onboard device mechanically coupled to the asset, the onboard device electrically coupled to a source of power of the asset, and the onboard device receiving power from the asset; detecting a loss of power provided to the onboard device, the loss of power indicative of tampering with the onboard device, and the detecting by the onboard device; and sending a message by wireless transmission, the message indicative of tampering with the onboard device, and the sending by the onboard device during the loss of power.