The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.
When the throttle position sensor fails, the engine's computer tends to overcompensate with fuel, leading black exhaust coming from the tailpipe. There is a strong possibility of engine misfires, and the check engine light will come on.
Throttle position sensors can also develop "dead spots," or certain places along the throttle curve where it doesn't get a reading. When this happens, the above symptoms can occur but then stop when you further press or let off the gas pedal.
When the vehicle speed sensor fails or the wiring harness prevents signal transmission, the speedometer is the first thing that will stop functioning properly. This can be an intermittent issue where the speedometer only works occasionally, the speedometer may cease all function, or the speedometer may read erratically or incorrectly. Also, the traction control and anti lock brake warning lights specific to each vehicle may be illuminated, depending on the design of those systems. You may notice the vehicle hesitate to accelerate, cruise control will not function properly, and the vehicle may not shift properly through all of the gears.
In the event that a wheel speed sensor fails, the ABS, traction control system (TCS) and manufacturer specific stability control system lights will illuminate, informing the driver that the systems are disabled. The vehicle will be more prone to tire slip, and normal driving patterns may need to be adjusted to correct for the loss of computer control. On older vehicle's, the speedometer can be affected, causing illumination of the check engine light as well.
The cruise control switch can cause complete failure of the cruise control feature, but in a lucky scenario only partial functionality will be lost. This means that the cruise control may come on, but that it will not increase in speed automatically, or the cancel button does not work leading the driver to cancel cruise control with the foot brake. In some vehicles, the cruise control light may illuminate, or a warning message may be displayed due to lack of functionality.
When troubleshooting cruise control issues in your Mercury Mariner, begin by checking the basics to avoid unnecessary complications. Start with the Powertrain Control Module (PCM) to see if there are any stored error codes that could indicate the source of the problem. Next, inspect the brake/cruise switch, as a malfunction here can prevent the cruise control from engaging. Additionally, examine the fuses related to the cruise control system; a blown fuse can easily disrupt functionality. If these initial checks do not resolve the issue, consider the throttle sensor and any potential vacuum leaks, as these can also affect cruise control performance. By following this diagnostic approach, you can systematically identify and address the root cause of the cruise control problems, ensuring a more efficient and effective repair process.
When troubleshooting cruise control issues in a Mercury Mariner, it's essential to understand the common problems that may arise. One frequent culprit is the brake/cruise switch, which can malfunction or be inadvertently pressed, preventing the cruise control from engaging. Additionally, the Powertrain Control Module (PCM) plays a critical role in managing cruise control functions, so checking for any stored diagnostic trouble codes can provide valuable insights into underlying issues. Other potential problems include a blown fuse, which can disrupt electrical systems, or a faulty brake light switch that may signal to the system that the brakes are engaged. Engine-related issues, such as throttle sensor failures, can also impact cruise control performance. By systematically examining these components, DIYers can effectively diagnose and address the root causes of cruise control malfunctions, ensuring a smoother driving experience.
When the cruise control in your Mercury Mariner is malfunctioning, it’s crucial to address the issue without delay. Ignoring symptoms such as erratic acceleration or failure to engage can not only compromise your driving experience but also pose significant safety risks. For instance, a faulty brake pedal switch could prevent the cruise control from disengaging when needed, leading to potential accidents. Additionally, issues like a defective throttle position sensor can cause the engine to behave unpredictably, resulting in excessive fuel consumption and harmful emissions. By promptly diagnosing and resolving these problems—such as checking the Powertrain Control Module for error codes, inspecting brake lights, and ensuring the integrity of the throttle control system—you can maintain both your vehicle's performance and your safety on the road. Taking these steps not only prevents further damage but also ensures a smoother and safer driving experience.
Read about related problems experienced by other Mercury Mariner drivers like you.
See what others are asking about their Mercury Mariner. Get answers from RepairPal's community of auto experts and enthusiasts.
