1992 Porsche 968 Cruise Control Isn't Working

Diagnosing Common Issues with the Cruise Control System in Your 1992 Porsche 968 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 1992 Porsche 968 cruise control isn't working are failed control module, sensor or switch issues, or throttle actuation problems.
  • Sensor: A faulty sensor can lead to incorrect readings, causing issues with engine performance or triggering warning lights on the dashboard.
  • Control Module: A faulty control module can result in 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 acceleration and poor engine 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 1992 Porsche 968 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.

If the cruise control refuses to turn on at all, the actuator could be at fault. Likewise, if the cruise control stays on but does not maintain a consistent speed, the problem could be a bad actuator. In extreme cases, a malfunctioning actuator could cause the throttle to stick and prevent the vehicle from slowing down. These symptoms may point to a bad actuator. They may also point to other problems with the cruise control and related systems.

What are the first steps to diagnose cruise control issues in a 1992 Porsche 968?

To effectively diagnose cruise control issues in a 1992 Porsche 968, start by checking the cruise control components, including the control module, throttle, and sensors, to ensure they are functioning properly. Next, inspect the power supply, as blown fuses or faulty connections can disrupt the system's operation. It's also important to examine the speedometer cable, since any malfunction here can affect the cruise control's performance. Additionally, consider the brake and clutch interlock systems; ensure that the cruise control disengages when the brake is pressed and re-engages correctly after releasing the clutch. Finally, consulting the service manual can provide specific diagnostic steps and circuit information tailored to your vehicle. By following this structured approach, you can systematically identify and address the underlying issues affecting your cruise control system.

What common issues cause cruise control failure in a 1992 Porsche 968?

When troubleshooting cruise control failure in a 1992 Porsche 968, it's essential to consider several common problems that could be at play. One of the primary culprits is a failed control module, which can disrupt the entire cruise control system. Additionally, issues with the throttle actuation can prevent the system from maintaining speed, while a malfunctioning throttle position sensor may cause the engine computer to overcompensate with fuel, leading to noticeable black exhaust. Another potential issue is the clutch switch, which, if slightly out of adjustment, can mislead the cruise control head unit into thinking the clutch is disengaged, thereby disabling the cruise functionality. By systematically checking these components, DIYers can effectively diagnose and resolve the underlying issues affecting the cruise control system in their Porsche 968.

How urgent is it to repair the non-functioning cruise control in a 1992 Porsche 968?

When evaluating the urgency of repairing the non-functioning cruise control in your 1992 Porsche 968, it's essential to weigh both your driving habits and the potential risks associated with the malfunction. If you often embark on long highway drives, the absence of cruise control can lead to fatigue and reduced comfort, making the repair more pressing. Conversely, if your driving is primarily confined to city streets, where maintaining a constant speed is less critical, you might prioritize other maintenance tasks. However, neglecting the issue could lead to more significant problems down the line, especially if the malfunction stems from a simple fix like a blown fuse or a faulty brake pedal switch. On the other hand, if the root cause is a more complex component, such as the cruise control module, delaying the repair could result in further damage and increased repair costs. Ultimately, assessing your driving needs alongside the potential consequences of inaction will help you determine how urgently you should address the cruise control issue in your Porsche 968.

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