Like many car owners, I’ve come to appreciate the Actron Cp9135 Obd2 Code Reader And Scanner as a user-friendly tool for diagnosing car problems. It recently helped me pinpoint an ignition coil failure in my 1998 Mercedes-Benz E320 (W210, M104 engine). However, I’m now facing a perplexing issue: the ETS and ABS lights are frequently illuminating, especially when turning, but my Actron CP9135 reports “No Faults Detected.” This situation raises several important questions about the limitations of OBD2 scanners like the CP9135 and how to properly diagnose these specific Mercedes-Benz issues.
Understanding OBD2 Scanner Limitations: Why No ETS/ABS Codes?
It’s crucial to understand that not all OBD2 scanners are created equal. While the Actron CP9135 is excellent for reading generic OBD2 Diagnostic Trouble Codes (DTCs) – the kind related to engine and emissions – it may not access systems beyond the engine and transmission in every vehicle. Specifically, systems like ABS (Anti-lock Braking System), ETS (Electronic Traction System), and SRS (Supplemental Restraint System/Airbags) often operate on different communication protocols. Therefore, a basic OBD2 scanner like the CP9135 might not be designed to read the specific fault codes generated by these systems in a 1998 Mercedes-Benz E320. This limitation is common with many entry-level OBD2 scanners; they are primarily focused on the federally mandated emission-related diagnostics.
Potential Causes for ETS/ABS Lights on a Mercedes-Benz E320
The fact that the ETS and ABS lights are activating, particularly during turns, suggests a few potential areas to investigate on your W210 E320:
- Wheel Speed Sensors: These sensors are vital for both ABS and ETS to function correctly. Damage, dirt, or failure in a wheel speed sensor is a common cause for these lights, especially when turning as this can exacerbate a marginal sensor issue.
- Brake Light Switch: Although you’ve replaced it, a faulty or incorrectly adjusted brake light switch can still cause ETS/ABS issues in Mercedes-Benz models of this era. Even a slight malfunction can confuse the systems.
- Steering Angle Sensor: Less common but still possible, a steering angle sensor issue could trigger ETS/ABS lights when turning.
- Low Battery Voltage: Mercedes-Benz systems are sensitive to voltage fluctuations. A weak battery or poor charging system can sometimes cause spurious warnings and light activations.
- Brake System Components: Issues within the braking system itself, beyond just the switch, could also be at play.
Actron CP9135 and IM Readiness: Resetting for Emissions Testing
Regarding resetting IM Readiness functions with your Actron CP9135, it is generally safe to use this function after addressing any underlying issues that triggered fault codes. IM Readiness monitors are indicators that show if your vehicle’s emission control systems have been tested and are ready for an emissions test. However, continuously resetting these without fixing the root cause of emission-related problems is not advisable and may not resolve the underlying issue causing your ETS/ABS lights.
Brake Light Condition and ETS/ABS Activation
Yes, a malfunctioning brake light, especially one with arcing issues at the bulb holder, could potentially contribute to ETS/ABS light activation. Mercedes-Benz systems are interconnected, and electrical anomalies can sometimes affect seemingly unrelated systems. The arcing suggests a potential ground issue or electrical instability which could be disrupting the sensitive electronic systems controlling ETS and ABS.
Stop Light Switch: Re-evaluation and Testing
While you tested the new stop light switch upon installation, it might be worth re-examining it. Ensure it is correctly installed, properly adjusted, and that the contacts are clean and making solid connections. Even new parts can be faulty, and the brake light switch is a known culprit for various Mercedes-Benz electronic issues. Consider testing it again, or even temporarily trying a different switch if possible, to rule it out definitively.
Conclusion: Stepping Beyond Basic OBD2 for ETS/ABS Diagnostics
In conclusion, while the Actron CP9135 OBD2 scanner is a helpful tool for many diagnostics, it appears to be limited in reading the specific codes related to your Mercedes-Benz E320’s ETS and ABS systems. To effectively diagnose the ETS/ABS light issue, you likely need a more advanced scanner capable of reading Mercedes-Benz specific codes, or consult with a mechanic who has access to such diagnostic equipment. Addressing the brake light issue and re-checking the stop light switch are good starting points, but a deeper diagnostic scan is recommended to pinpoint the root cause of your ETS/ABS light activation.
