1998 Lexus SC400 Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your 1998 Lexus SC400 and How to Fix Them

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Reviewed by
Devin Cabugcal
Written by RepairPal Car Genius
Updated January 14, 2025
0%
30% chance it's the
Sensor
0%
25% chance it's the
Control Module
0%
25% chance it's the
Throttle
0%
20% chance it's
Something else
The most common reasons a 1998 Lexus SC400 cruise control isn't working are failed control module, sensor or switch issues, or throttle actuation problems.
  • Sensor: A faulty or malfunctioning sensor can lead to incorrect readings, causing issues with engine performance or other systems relying on accurate data.
  • Control Module: A faulty control module can lead to erratic vehicle behavior or failure of various electronic systems due to improper signal processing.
  • Throttle: A faulty throttle body or a defective accelerator pedal position sensor may be causing inconsistent throttle response.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 1998 Lexus SC400 cruise control isn't working?

Common Repairs

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.

What are the initial diagnostic steps to troubleshoot the non-functional cruise control in a 1998 Lexus SC400?

When troubleshooting the non-functional cruise control in a 1998 Lexus SC400, it's essential to adopt a systematic diagnostic approach. Start by checking the cruise control fuse, as a blown fuse is a straightforward issue that can easily disable the system. Next, inspect the cruise control switch located on the steering wheel; a malfunctioning switch may prevent the cruise control from engaging. Following this, verify the brake light switch, since a faulty brake light switch can inadvertently disable the cruise control system. Additionally, examine the vehicle speed sensor, which is crucial for the cruise control to maintain a set speed. Lastly, utilize a diagnostic scanner to check for any stored error codes in the vehicle's onboard diagnostic system, as these codes can provide insights into underlying issues. By methodically working through these steps, you can effectively diagnose and address the problem with your cruise control system.

What are the common problems that could cause the cruise control to stop working in a 1998 Lexus SC400?

When dealing with a malfunctioning cruise control system in a 1998 Lexus SC400, it's crucial to understand the common problems that may be at play. One of the primary culprits could be a faulty cruise control switch, which may fail to engage the system properly. Additionally, a blown fuse can disrupt the electrical flow necessary for the cruise control to function, making it a straightforward issue to check and replace. Another potential issue is vacuum leaks within the cruise control system; these leaks can significantly impair its operation by preventing the system from maintaining the desired speed. Furthermore, a defective speed sensor can lead to inaccurate speed readings, which directly affects the cruise control's ability to hold a set speed. It's also important to consider the brake light switch; if this switch is malfunctioning, it may prevent the cruise control from activating altogether. Lastly, problems with the throttle cable can hinder the system's ability to adjust the vehicle's speed as needed. By systematically diagnosing these areas, DIYers can effectively identify and resolve the underlying issues, restoring the cruise control functionality in their Lexus SC400.

How urgent is it to address the non-functioning cruise control in a 1998 Lexus SC400?

When it comes to the non-functioning cruise control in your 1998 Lexus SC400, understanding the urgency of the situation is crucial for both safety and driving comfort. While it may not pose an immediate threat like brake failure, a malfunctioning cruise control system can lead to significant inconveniences, especially during long drives on highways where maintaining a consistent speed is essential. Ignoring this issue could not only result in increased driver fatigue but also lead to higher fuel consumption due to erratic speed control, ultimately costing you more in the long run. Moreover, delaying repairs might exacerbate the problem, potentially causing further damage to the cruise control system and increasing repair costs. Therefore, while it may not be an emergency, addressing the cruise control issue promptly is advisable to enhance your driving experience, ensure safety, and avoid unnecessary expenses.

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1998 Lexus SC400 Cruise Control Issues & Repairs | RepairPal