A common issue with VCDS 16.8.4 cables is a failed connection to the vehicle’s OBD2 port. This often manifests as a lack of LED indication on the cable, signifying no communication. This article explores potential causes and solutions for this problem, focusing on a specific case of flashing a new firmware to an ATMEGA162 microcontroller within a VCDS cable.
Understanding the Problem: No OBD2 Connection with VCDS 16.8.4 Cable
One user encountered a problem after attempting to update their VCDS cable with VCDS 18.9 firmware (including software, ATMEGA162 dump, and fuse settings). Despite a seemingly successful flashing process using avrdude, the cable failed to connect to the car, indicated by a non-illuminating LED.
The user provided the following terminal output from the flashing process:
avrdude -c FT232H -p m162 -P /dev/ttyUSB0 -b 234375 -U flash:w:flashATM162.BIN:r -U eeprom:w:eepromATM162.BIN:r -U lfuse:w:0xcd:m -U hfuse:w:0xda:m -U efuse:w:0xf9:m -U lock:w:0xcc:m ... (Output truncated for brevity) ... avrdude done. Thank you.The output suggests a successful write and verification of the flash, EEPROM, and fuse bits. However, the lack of LED activity points to a fundamental connection problem.
Potential Causes and Solutions
Several factors can contribute to a failed Cable Vcds 16.8.4 Obd2 Connection:
- Incorrect Fuse Bit Settings: While the provided output shows fuse bits being written, their values (lfuse: 0xcd, hfuse: 0xda, efuse: 0xf9) might be incorrect for the specific ATMEGA162 chip used in the VCDS cable. Referencing the official VCDS documentation or community forums for the correct fuse bit settings for your specific hardware revision is crucial.
- Incompatible Firmware: Using VCDS 18.9 firmware on hardware designed for VCDS 16.8.4 might lead to compatibility issues. While sometimes possible, using firmware specifically intended for your cable version is generally recommended.
- Hardware Issues: A damaged ATMEGA162 chip, faulty FTDI chip (FT232H in this case), or issues with other components on the cable’s PCB could prevent proper operation.
- Driver Problems: Outdated or incorrectly installed drivers for the FTDI chip can hinder communication between the cable and the computer. Ensuring the latest drivers are installed is essential.
The user also mentioned that reverting to a previous 1.96 firmware restores the LED functionality (red then green), but a “Failed self test” error persists. This indicates a potential incompatibility between the hardware and the attempted 18.9 firmware.
Recommendations for Establishing a Successful Connection
- Verify Fuse Bits: Double-check the correct fuse bit settings for your specific VCDS cable hardware revision against reliable sources like the official Ross-Tech website.
- Use Correct Firmware: Download and flash the firmware specifically designed for VCDS 16.8.4. Attempting to use newer firmware versions can lead to unforeseen complications.
- Check Hardware: Visually inspect the cable for any physical damage. If possible, test with a known working cable to rule out hardware problems.
- Update Drivers: Ensure you have the latest FTDI drivers installed on your computer.
By systematically addressing these potential issues, users can increase the likelihood of resolving cable vcds 16.8.4 obd2 connection problems and achieving a successful diagnostic session. If problems persist after these troubleshooting steps, consulting the official Ross-Tech support forums or contacting their technical support directly is recommended.
