I recently purchased an Actron CP9135 OBD2 scanner, and it proved invaluable when diagnosing a faulty ignition coil in my 1998 Mercedes-Benz E320 (W210) with an M104 engine. I was impressed by its accuracy and ease of use for reading engine codes. However, I’m now facing a new challenge: the ETS and ABS lights are frequently illuminating, especially when turning, but my Actron scanner reports “No Faults Detected.” This situation raises some important questions about scanner capabilities and diagnosing Mercedes-Benz systems.
Understanding OBD2 Scanner Limitations with ETS/ABS Systems
It’s crucial to understand that while OBD2 scanners like the Actron CP9135 are excellent for reading generic powertrain (engine and transmission) Diagnostic Trouble Codes (DTCs), their coverage of other vehicle systems can be limited. Systems like ABS (Anti-lock Braking System), ETS (Electronic Traction System), and SRS (Supplemental Restraint System/Airbags) often operate on different communication protocols or require more advanced diagnostic tools to access their fault codes.
When your Actron scanner indicates “No Faults Detected” in the face of ETS and ABS light activation, it likely means the scanner is functioning correctly within its designed parameters. It simply isn’t designed to communicate with the ETS/ABS control modules on your Mercedes-Benz to retrieve specific fault codes from those systems. These systems often require a scanner that is capable of reading manufacturer-specific codes, or a more advanced scan tool designed for comprehensive diagnostics.
Why Your Actron Scanner Might Not Detect ETS/ABS Faults
The “no faults” message from your Actron CP9135 for the ETS/ABS lights doesn’t imply there are no problems. It suggests the issue lies within systems beyond the scope of this particular OBD2 scanner’s diagnostic capabilities. Generic OBD2 scanners are primarily focused on emissions-related faults, which are standardized across most vehicles. Systems like ETS and ABS are manufacturer-specific and often require tools that can access proprietary diagnostic protocols.
Addressing Potential Causes and Diagnostic Steps
You mentioned several potential causes for ETS/ABS light activation, such as the brake light switch, battery voltage, wheel speed sensors, and steering wheel tilt sensor. These are indeed common culprits for these systems on Mercedes-Benz vehicles of this era.
Given that your Actron scanner isn’t providing the necessary fault codes, here are recommended steps:
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Consider a Scanner with Enhanced System Coverage: To accurately diagnose ETS/ABS issues, you might need a scanner that specifically supports Mercedes-Benz systems or offers enhanced diagnostics beyond basic OBD2. These scanners can often read manufacturer-specific codes for ABS, ETS, SRS, and other systems.
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Professional Diagnostic Scan: The most reliable approach is to have your Mercedes-Benz scanned by a professional mechanic or Mercedes-Benz specialist using a high-end diagnostic scan tool. These tools have the necessary software and hardware to communicate with all vehicle systems, including ETS/ABS, and retrieve detailed fault codes.
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Investigate Basic Checks: While waiting for a professional scan or considering a new scanner, you can perform some basic checks:
- Brake Light Function: You mentioned a faulty brake light due to arcing. A malfunctioning brake light circuit can indeed trigger ETS/ABS lights. Ensure all brake lights are functioning correctly.
- Battery Voltage: Low battery voltage can sometimes cause spurious error messages. Check your battery’s voltage and charging system.
- Visually Inspect Wheel Speed Sensors: Although difficult to definitively test without proper equipment, a visual inspection of wheel speed sensor wires for damage might reveal obvious issues.
Regarding your specific questions:
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Do I need to purchase a different type of scanner to retrieve the ETS/ABS codes? Likely, yes. To read ETS/ABS codes on your 1998 Mercedes-Benz E320, you will probably need a scanner that offers enhanced diagnostics or Mercedes-Benz specific coverage.
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Should I use my scanner to reset the IM Readiness functions? Resetting IM Readiness functions is generally done after emissions-related repairs to prepare for an emissions test. It’s not directly related to diagnosing ETS/ABS issues and is not necessary in this situation.
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Could this condition be causing the ETS/ABS lights to activate due to a brake light issue? Yes, a faulty brake light circuit, as you described, is a plausible cause for ETS/ABS light activation and should be addressed.
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Should I replace the stop light switch again? Since you recently replaced the stop light switch and tested it, it’s less likely to be the immediate issue unless the replacement switch is also faulty. However, it’s still a possibility. Ensure the brake light circuit and bulbs are functioning correctly first.
Conclusion
While your Actron CP9135 OBD2 scanner is a useful tool for basic engine diagnostics, diagnosing ETS/ABS light issues on your Mercedes-Benz E320 likely requires a more specialized scan tool or professional diagnostic service. Addressing the brake light issue is a good starting point, but further investigation with appropriate diagnostic equipment is recommended to pinpoint the root cause of the ETS/ABS light activation.
