Experiencing a “Display Defective” error in your 1997 Benz W210 can be perplexing. This message, while vague, often points to a common issue within these models related to the coolant and washer fluid sensor system. Mercedes-Benz, in an effort to streamline input points, ingeniously wired both sensors in series to the display computer.
The system is designed to differentiate between a low coolant and low washer fluid situation through unique resistance values in each sensor. Each sensor has specific series and shunt resistors. When a sensor triggers an alert, the computer reads the combined resistance. By interpreting these distinct resistance combinations, the system can pinpoint whether the coolant or washer sensor is signaling a problem.
However, when the measured resistance falls outside of these expected values, the system defaults to the generic “Display Defective” message. This often indicates that one of the sensors has failed, most likely due to an open circuit.
Fortunately, resolving this issue is often straightforward and cost-effective. Replacing the washer sensor is typically a quick task, often taking less than 30 minutes. Addressing the coolant sensor is slightly more involved as it necessitates draining some coolant from the reservoir before replacement. The good news is that both sensors are individually inexpensive, usually costing under $40 in total.
Anecdotal evidence suggests the washer sensor is positioned earlier in the series circuit. In some cases, simply replacing a faulty washer sensor has been enough to clear the “Display Defective” message, even if the underlying issue was initially unclear. This is because an open circuit in the washer sensor might disrupt the entire sensor circuit, triggering the general error.
Therefore, if you encounter the “Display Defective” message in your 1997 Benz, inspecting and potentially replacing the washer and coolant sensors should be a primary troubleshooting step. It’s a DIY-friendly fix that can save you time and money, getting your classic Benz back to optimal condition.
