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.
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.
When troubleshooting the cruise control system in a 1991 BMW 318i, it's essential to consider several common problems that may be at play. One frequent culprit is a failed control module, which can disrupt the entire system's functionality. Additionally, issues with sensors or switches can prevent the cruise control from engaging properly. Throttle actuation problems are another significant factor; if the throttle valve is stuck or the throttle control system is malfunctioning, it can lead to erratic behavior or complete failure of the cruise control. A blown fuse or a defective brake pedal switch can also interrupt the system, as these components are critical for safe operation. In older models, a broken vacuum line may be responsible for the malfunction, while problems with the cruise control and throttle cables, such as a broken plastic bushing, can cause the cables to become stuck, further complicating the issue. By systematically checking these components, DIYers can effectively diagnose and resolve the cruise control problems in their BMW 318i.
Addressing the non-functioning cruise control in a 1991 BMW 318i is crucial for both safety and vehicle performance. Ignoring this issue can lead to more significant problems, such as increased driver fatigue during long trips, which can compromise safety on the road. The cruise control system relies on various components, including sensors and the internal computer, which may require professional recalibration if they malfunction. Common culprits for cruise control failure include blown fuses, defective brake pedal switches, and throttle control system issues. A simple inspection of the fuses can often reveal whether a blown fuse is disrupting the power supply to the cruise control system. Additionally, a dirty or broken cruise control button can prevent activation, making it essential to check for debris that may be obstructing its function. By addressing these issues promptly, you not only restore the convenience of cruise control but also ensure a safer driving experience, preventing potential accidents or further damage to your vehicle.
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