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.
To effectively diagnose the non-functioning cruise control in your 1990 BMW 735i, start by reading the BMW fault codes, as this will provide valuable insights into any underlying issues. Utilizing a BMW scanner is essential for this step, allowing you to retrieve specific fault codes that can guide your troubleshooting process. Next, examine the cruise control buttons to ensure they are functioning correctly and receiving the appropriate signals. This can often be done by checking the connections and wiring associated with the buttons. Following this, inspect the engine controller, focusing on the measurement block that corresponds to the cruise control input bits. By pressing the cruise control buttons, you should observe changes in the input readings; if not, this could indicate a deeper issue within the system. By following these steps, you can systematically identify and address the problems affecting your cruise control, making your DIY repair process more efficient and effective.
When troubleshooting cruise control issues in a 1990 BMW 735i, it's essential to understand the common problems that may be at play. One of the primary culprits is the rear brake light switch, which is known to malfunction and can prevent the cruise control from engaging properly. Additionally, various components within the cruise control system itself may be faulty, so it's crucial to inspect these parts to ensure they are functioning as intended. External factors can also play a role; for instance, debris or adverse weather conditions can temporarily disrupt the adaptive cruise control system. Furthermore, while specific information on the 1990 model may be limited, general transmission issues such as low fluid levels or leaks can significantly impact the cruise control's performance. By systematically checking these areas, DIYers can effectively identify and resolve the root causes of cruise control malfunctions in their BMW 735i.
When considering the urgency of fixing the non-functioning cruise control in a 1990 BMW 735i, it's essential to recognize that while it may not seem like an immediate emergency, the implications of neglecting this issue can be significant. A malfunctioning cruise control system can lead to discomfort during long drives, as it eliminates the convenience of maintaining a steady speed without constant manual adjustments. Moreover, the failure of this system could be a symptom of deeper issues, such as problems with the vehicle's speed sensors or control modules, which may affect overall performance and safety. Ignoring these signs could result in decreased fuel efficiency, as drivers struggle to maintain a consistent speed, potentially leading to higher fuel costs over time. Additionally, if the cruise control failure stems from a faulty component, addressing it promptly is crucial to prevent further damage and ensure safe driving conditions. Therefore, while it may not be an urgent repair, it is advisable for DIY enthusiasts to investigate the issue sooner rather than later to maintain the vehicle's efficiency and safety.
See what others are asking about their BMW 735i. Get answers from RepairPal's community of auto experts and enthusiasts.
Read about related problems experienced by other BMW 735i drivers like you.