1999 Lexus SC300 Cruise Control Isn't Working

Fixing Cruise Control Issues in 1999 Lexus SC300

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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 1999 Lexus SC300 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 1999 Lexus SC300 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.

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 steps to diagnose the cruise control issue in a 1999 Lexus SC300?

To effectively diagnose cruise control issues in your 1999 Lexus SC300, begin with the simplest solutions and progressively tackle more complex components. Start by checking the fuse associated with the cruise control system, as a blown fuse can easily disrupt functionality. Next, inspect the cruise control switch to ensure it is operational; a malfunctioning switch can prevent the system from engaging. Following this, examine the speed sensor, which is vital for maintaining the desired speed; any issues here can directly affect cruise control performance. Additionally, test the brake pedal switch, as it is designed to disengage the cruise control when the brakes are applied; if this switch is faulty, it may cause the system to malfunction. Finally, utilize a diagnostic scanner to check for any error codes that may provide insights into underlying issues. By following this structured approach, you can effectively identify and resolve cruise control problems in your vehicle.

What are the common problems that could cause the cruise control to stop working in a 1999 Lexus SC300?

When dealing with a malfunctioning cruise control system in a 1999 Lexus SC300, it's important to consider several common issues that could be at play. One of the first things to check is the cruise control switch, as a faulty switch can prevent the system from engaging properly. Additionally, a blown fuse within the cruise control circuit can lead to a complete failure of the system, so inspecting the fuses is a crucial step. Another potential culprit is vacuum leaks, which can disrupt the necessary pressure for the cruise control to function effectively. The speed sensor also plays a vital role; if it is defective, it may cause the cruise control to malfunction or disengage unexpectedly. Furthermore, issues with the brake light switch can inhibit the activation of the cruise control, as the system is designed to disengage when the brakes are applied. Lastly, a malfunctioning throttle cable can interfere with the cruise control's ability to maintain speed. By systematically checking these components, DIYers can accurately diagnose and address the cruise control issues in their Lexus SC300.

How urgent is it to repair the non-functioning cruise control in a 1999 Lexus SC300?

When evaluating the urgency of repairing the non-functioning cruise control in a 1999 Lexus SC300, it's essential to recognize the potential safety risks associated with its malfunction. A properly functioning cruise control system is designed to maintain a steady speed, which can significantly enhance driving safety, especially on long journeys. If the system fails, it may lead to erratic speed changes, increasing the risk of accidents. Additionally, the absence of cruise control can lead to driver fatigue, as maintaining constant speed manually requires more effort and attention, potentially compromising comfort during extended drives. Furthermore, neglecting this repair could impact the vehicle's resale value; prospective buyers often look for well-maintained features, and a malfunctioning cruise control system may deter them. Therefore, while it may not be an immediate emergency, addressing the cruise control issue promptly is advisable to ensure safety, enhance driving comfort, and preserve the vehicle's value.

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