1999 Pontiac Grand Prix Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your 1999 Pontiac Grand Prix and How to Fix Them

Find Repair Location
Reviewed by
Aisha
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 Pontiac Grand Prix 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 Pontiac Grand Prix 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.

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.

A faulty cruise control module will simply result in deactivation of cruise control settings. This is because a detected error in the cruise control system could lead to hazardous driving conditions, so the module will be disabled, and the cruise control system warning light will be displayed. This will be a different message depending on make and model, and a warning light or message may be displayed on the driver instrument cluster.

What are the initial steps to diagnose the non-functioning cruise control in a 1999 Pontiac Grand Prix?

To effectively diagnose the non-functioning cruise control in a 1999 Pontiac Grand Prix, start with the simplest checks before moving on to more complex issues. Begin by inspecting the cruise control fuse, as a blown fuse can easily disrupt the system's operation. If the fuse is intact, proceed to examine the cruise control switch for any visible damage or wear, as this component is crucial for activating the system. Next, check the brake pedal switch, ensuring it is functioning properly; a malfunctioning switch can prevent the cruise control from engaging altogether. Finally, inspect the vacuum lines for any leaks, as these can significantly impact the cruise control's performance. By following this diagnostic approach, you can systematically identify and address the root cause of the cruise control issue, making your DIY repair efforts more effective.

What are the common problems that could cause the cruise control to stop working in a 1999 Pontiac Grand Prix?

When the cruise control in a 1999 Pontiac Grand Prix ceases to function, several common problems may be at play. One of the first areas to check is the fuse, as a blown fuse can easily disrupt the system's operation. Additionally, the brake pedal switch is crucial; if it is defective, it may prevent the cruise control from engaging. Another potential culprit is the throttle, which can malfunction and hinder the system's ability to maintain speed. It's also important to consider the control module and various sensors, as these components can fail and lead to operational issues. Lastly, if any recent work has been done on the vehicle, ensure that the wiring harness is properly connected, particularly after changing the multifunction switch, as loose connections can interfere with the cruise control's functionality. By systematically checking these areas, DIYers can often identify and resolve the issue without needing professional assistance.

How urgent is it to address the non-functioning cruise control in a 1999 Pontiac Grand Prix?

Addressing the non-functioning cruise control in a 1999 Pontiac Grand Prix is not just a matter of convenience; it is a critical safety concern that requires immediate attention. A malfunctioning cruise control system can lead to unpredictable vehicle behavior, affecting acceleration and overall driving stability, which can compromise your safety and that of others on the road. Moreover, if the cruise control fails to disengage when needed, it poses a significant risk, especially in emergency situations where quick response is essential. Additionally, a faulty cruise control indicator can mislead the vehicle's control system, further complicating the issue. Common culprits behind these failures, such as blown fuses, defective brake lights, or engine problems, can escalate if left unaddressed, potentially leading to more severe damage and costly repairs. Therefore, it is crucial to prioritize the repair of your cruise control system to ensure a safe and reliable driving experience.

You’ve got options with RepairPal

Whether you need a more accurate auto repair estimate or help finding a reputable shop in your area, we’ve got you covered.