1998 GMC Safari Cruise Control Isn't Working

Common Causes of Cruise Control Malfunctions in Your 1998 GMC Safari and How to Fix Them

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Reviewed by
Bo Fader
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 GMC Safari 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 GMC Safari 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.

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 steps to diagnose a non-functioning cruise control system in a 1998 GMC Safari?

To effectively diagnose a non-functioning cruise control system in a 1998 GMC Safari, it's essential to adopt a systematic diagnostic approach that prioritizes simpler checks before delving into more complex issues. Begin by inspecting the fuse associated with the cruise control; a blown fuse is a straightforward fix that can often resolve the problem. Next, assess the cruise control switch to ensure it is operational, as a malfunctioning switch can easily disrupt the system's functionality. Following this, examine the brake pedal switch, which is crucial for disengaging the cruise control when brakes are applied; any faults here can lead to significant issues. The vehicle speed sensor is another critical component to check, as it provides necessary data for the cruise control to function correctly. Additionally, inspect the vacuum lines for any leaks or damage, particularly since older models like the Safari may rely on these for operation. Finally, utilizing a diagnostic scanner to check for error codes can provide valuable insights into any underlying issues that may not be immediately apparent. By following this structured approach, you can efficiently identify and address the root causes of cruise control malfunctions in your vehicle.

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

When dealing with a malfunctioning cruise control system in a 1998 GMC Safari, it's crucial to understand the common problems that could be at play. One of the first things to check is the fuse; a blown fuse can easily disrupt the entire system, rendering it inoperable. Next, consider the brake pedal switch, which is designed to disengage the cruise control when the brake is applied. If this switch is faulty, it may prevent the cruise control from engaging at all. Additionally, the cruise control module itself could be defective, which may require replacement if it fails to function correctly. Another potential issue is vacuum leaks within the system, which can hinder the cruise control's ability to maintain speed effectively. Lastly, a faulty speed sensor can lead to inaccurate speed readings, further complicating the cruise control's performance. By systematically diagnosing these areas, DIYers can effectively identify and address the root cause of the cruise control issues in their GMC Safari.

How urgent is it to repair the non-functioning cruise control in a 1998 GMC Safari?

While the non-functioning cruise control in your 1998 GMC Safari may not seem like an urgent repair, it is essential to recognize the potential implications of neglecting this issue. Cruise control plays a significant role in enhancing safety during long drives by helping maintain a consistent speed, which can reduce driver fatigue and improve overall road safety. Additionally, a functional cruise control system contributes to a more comfortable driving experience, particularly on highways where maintaining speed can alleviate the monotony of long trips. Furthermore, addressing this repair can positively impact the resale value of your vehicle; prospective buyers often prefer vehicles with all features in working order. Therefore, while it may not be an immediate emergency, prioritizing the repair of your cruise control can lead to a safer, more enjoyable driving experience and help preserve the value of your GMC Safari.

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1998 GMC Safari Cruise Control Malfunction Guide | RepairPal