Many budget-conscious car owners are drawn to the allure of cheap ELM327 OBD2 Bluetooth adapters. However, these devices often lack critical functionality. This article dissects a common fake ELM327 OBD2 adapter, highlighting its shortcomings and emphasizing the importance of choosing a reliable device.
My experience with a low-cost Bluetooth OBDII dongle began with disappointment. It failed to connect to my 2005 Dodge, unable to detect the SAE J1850 VPW protocol common in pre-2008 Chrysler/Dodge vehicles. Deconstructing the device revealed two stacked circuit boards. The top board housed a BEKEN BK3231Q Bluetooth chip and an NXP TJA1040 CAN protocol transceiver.
The underside of the top board featured a Microchip MCP2515 CAN controller. Surprisingly, the bottom board contained only voltage regulators for 5V and 3.3V. Crucially, most OBD-II pins were unconnected.
Comparing the connected pins to a standard OBD-II pinout diagram exposed the problem. While the 12V VCC (pin 16) and ground pins (pins 4 and 5) were connected, crucial protocol pins were missing. CAN (ISO15765) pins 6 and 14 were connected, as were ISO9141/14230 pins 7 and 15. However, J1850 PWM pins 2 and 10, and the J1850 VPW pin 2 were not connected. This explained the incompatibility with my Dodge. This design flaw renders the adapter useless for J1850 protocols used by older American car manufacturers like Chrysler, Dodge, Jeep, Ford, and GM. Newer vehicles (post-2008) generally utilize the CAN protocol, making this issue less prevalent.
A subsequent purchase of a different, slightly larger, Bluetooth OBD-2 reader yielded identical results. Despite the seller’s claims of full protocol support, it proved to be another fake ELM327 OBD2 device. Disassembly revealed the same internal components, confirming its limitations.
These experiences highlight a critical issue: cheap ELM327 OBD2 adapters often lack full protocol support. Furthermore, their lack of Bluetooth authentication poses a significant security risk. Any nearby hacker could potentially connect and access the vehicle’s CAN bus, potentially manipulating critical systems.
For reliable performance and security, invest in a trusted brand with proven compatibility and security features. The OBDLink LX Bluetooth, for example, offers comprehensive protocol support, sleep mode, and a security button for pairing, ensuring a secure connection. While more expensive, the peace of mind and functionality are worth the investment. Choosing the right ELM327 OBD2 adapter is crucial for both functionality and vehicle security.
