Morgans Auto Repair

Modern vehicle instrument clusters are filled with a multitude of warning lights, making it challenging to keep track of their meanings. Even experienced technicians can occasionally stumble upon an unfamiliar symbol, particularly in new model year vehicles or those from lesser-known brands.

Rather than attempting to cover every single light, it seems more beneficial to focus on the fundamental concepts that, surprisingly, aren’t widely recognized. This will serve as a guide for any car owner.

**The 3 Distinct Colors of Severity:**

While a dashboard may be adorned with a plethora of lights, they do not all carry the same degree of importance. Some lights serve as indicators, whereas others are genuine warning signals. Generally, the color of the illuminated symbol offers insight into the severity of the issue at hand.

Red signifies a critical warning or safety concern that demands immediate attention. Common examples include the battery light (representing the charging system) and the oil can light (indicating engine oil pressure). Failures in either the charging or lubrication systems can lead to engine shutdowns, potentially leaving a vehicle stranded in traffic.

Yellow comprises the next tier, offering alerts and recommendations. Common examples include the engine light (check engine) and tire light (low tire pressure). Issues indicated by these lights may not require instant action, but they certainly merit further investigation to ascertain the necessary steps.

Lastly, blue and green serve as indicator lights, informing the driver of specific conditions. Common instances include the headlight bulb light (for high beams) and the left/right arrow lights (for turn signals). While the systems linked to these lights present a minimal risk to other drivers if misused, these indicators remind the driver of their active status.

Trouble Codes May or May Not Be Present

Diagnostic Trouble Codes (DTCs) are five-digit identifiers that can be stored in one or more onboard computers of a vehicle. Each DTC is distinct and signifies a specific type of malfunction that has been detected, guiding automotive technicians on where to begin their diagnostic tests.

Typically, a warning light is activated when a DTC is logged; however, this is not universally true. The BRAKE indicator light serves as an excellent example of this occurrence, functioning as both an indicator and a warning light.

In certain situations, this light may illuminate merely because the parking brake is engaged. While this does not represent a failure, its importance to the vehicle's safe operation necessitates that it lights up in red.

Complicating matters further, the BRAKE indicator can also activate as a warning for low brake fluid, which may or may not trigger a DTC, depending on the vehicle model.

Finally, the BRAKE light might activate simultaneously with the closely related anti-lock brake system (ABS) if that system detects a fault.

**Multiple Warning Lights Do Not Always Indicate Multiple Failures**

From my conversations with numerous customers, I’ve learned that encountering multiple warning lights illuminating simultaneously can create significant anxiety. The reassuring news is that this situation does not always signify multiple issues!

Some systems are intricately connected and share many of the same components. Thus, when a problem arises with one of these common parts, it's logical that several systems could be impacted.

A prime illustration of this is a malfunctioning wheel speed sensor (WSS). The ABS and Traction Control systems rely on accurate wheel speed readings to assess if a wheel is locking up or slipping. When a WSS malfunctions, it triggers a wheel speed signal DTC, leading to the illumination of three warning lights: BRAKE, ABS, and Traction Control.

One or More Systems May Be Completely Inoperable

Building upon our discussion of the WSS failure scenario, it's essential to recognize that an additional issue is occurring in the background: the affected systems are rendered inoperable. This may be the most critical insight from this article.

I must clarify, however. If the BRAKE warning is illuminated due to a WSS failure, the brakes themselves are not disabled. The hydraulic system will still function, but the ABS warning light indicates that the system will not prevent wheel lockup. This poses a safety hazard during rapid emergency stops, particularly in adverse weather conditions or on loose, sandy surfaces.

Some may be thinking, “I’m a skilled driver. Vehicles didn’t come with ABS when I began driving. I can manage without it.” While that may be true, consider this: a driver cannot control the actions of other vehicles on the road, and collisions are labeled accidents for a reason.

Additionally, we must address the supplemental restraint system (SRS). If the SRS light is activated, airbags will not deploy in the event of a collision.

But why would engineers design vehicles this way? The rationale seems to be that having a disabled system is preferable to having a malfunctioning one. In the event of an SRS malfunction, non-deployed airbags are only problematic if an accident occurs, whereas an inappropriate airbag deployment could directly lead to a crash.

**The Check Engine Light Reveals More Than You Might Realize...**

The Check Engine Light (CEL) is undoubtedly the most recognized warning light. Most of us have likely encountered it at some point.

Did you know it’s also known by different names? Throughout the years and among various vehicle manufacturers, this warning light has been referred to as the Malfunction Indicator Lamp (MIL) and the Service Engine Soon (SES) light.

No matter the name, there are three intriguing and noteworthy conditions we can be sure of when this light comes on:

Firstly, the CEL signals that a Diagnostic Trouble Code (DTC) has been logged in the vehicle’s Engine Control Module (ECM). In the past, repair technicians had to manipulate certain wiring to make the CEL flash in a morse code-like manner to convey a two-digit code. Fortunately, modern diagnostic systems allow for much easier retrieval of DTCs through an onboard diagnostic (OBD) scanner.

Secondly, the CEL suggests that a malfunction has been identified that raises emissions levels. Wait a moment—doesn’t that mean a DTC could be recorded without triggering the CEL? Absolutely! This might be surprising to even the most car-savvy among us, but that’s the reality for vehicles sold in the United States.

Thirdly, when the CEL flashes, it signals a cylinder misfire condition. A misfire can damage the vehicle’s catalytic converter, which is responsible for cleaning the engine’s exhaust emissions. Consequently, the behavior of the CEL is adjusted to underscore the urgency of the situation.

As you can see, the CEL plays a crucial role in diagnosing, repairing, and safeguarding the emission system.

In true festive spirit, let’s wrap this up with a shiny bow!

**6 Things A Warning Light Can Indicate:**

- The severity of an issue

- A DTC may or may not be stored

- A system is active

- A system is disabled

- Emission levels have increased

- Component damage is imminent

It’s remarkable how a seemingly simple warning system is backed by such depth of thought and design. I hope you find this information enlightening, if not at least intriguing! Wishing you and your family a Merry Christmas and a Happy New Year!