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.
To effectively diagnose the non-functioning cruise control in your 1995 Jaguar XJ12, start by checking the control module and associated sensors, as these are often the root of the problem. Next, inspect the rubber bellows of the vacuum system, as wear or damage here can lead to functionality issues. It's crucial to verify the integrity of the vacuum system by checking for leaks, particularly in the booster hose, which can compromise performance. Additionally, examine the O-rings on the booster and purge valve plastic lines for any signs of leakage. Ensure that the cruise control module is receiving accurate information from the sensors and the engine control module (ECM). Finally, test the cruise control functionality by engaging it through the buttons and observing the system's response. By following this structured approach, you can systematically identify and resolve the issues affecting your cruise control system.
Not sure what's wrong?
Get help from a trusted expert
Read about related problems experienced by other Jaguar XJ12 drivers like you.
See what others are asking about their Jaguar XJ12. Get answers from RepairPal's community of auto experts and enthusiasts.