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.
To effectively diagnose the non-functioning cruise control in a 1991 BMW M5, begin with a systematic approach that prioritizes simpler checks before delving into more complex diagnostics. Start by assessing the basic functionality of the cruise control system, ensuring that the high beam switch and flashers are operational, as these can influence the cruise control's performance. Next, utilize a BMW scanner to read any fault codes, which will provide valuable insights into potential issues without prematurely replacing parts. Following this, inspect the key components of the cruise control system, including the on/off switch, set/resume switch, and brake and clutch switches, to confirm they are functioning correctly. Pay close attention to the wiring and connections associated with the cruise control; any loose or damaged wiring can lead to malfunctions. If error messages appear on the iDrive system, investigate these further, as they may point to specific problems that require resolution. Conduct thorough system checks, particularly on the MPM module, as it plays a crucial role in the electrical systems of the vehicle. If, after these steps, the issue remains unresolved, it may be time to consult a professional mechanic who specializes in BMWs for a more detailed diagnosis and repair. By following this structured diagnostic approach, you can effectively identify and address the issues affecting your BMW M5's cruise control system.
When troubleshooting cruise control issues in a 1991 BMW M5, it's essential to consider several common problems that could be causing the malfunction. One of the primary culprits is a faulty vehicle speed sensor, which plays a critical role in relaying speed information to the cruise control system. If this sensor is not functioning correctly, the system may struggle to maintain the desired speed. Additionally, electrical issues such as damaged wiring or poor connections can disrupt the cruise control's operation, leading to failure. Another area to inspect is the instrument cluster, as problems here can affect the speedometer and odometer readings, ultimately impacting the cruise control's functionality. Lastly, it's important to examine the various components within the cruise control system itself, as any malfunctioning parts can prevent the system from working as intended. By systematically diagnosing these potential issues, DIY enthusiasts can effectively restore the cruise control system to its proper working condition.
Not sure what's wrong?
Get help from a trusted expert
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 contemplating the urgency of repairing the non-functioning cruise control in your 1991 BMW M5, it's essential to weigh the potential consequences of inaction. While the absence of cruise control may not seem like an immediate emergency, it can significantly impact your driving experience, especially on long journeys where maintaining a consistent speed is crucial for comfort and reducing fatigue. Moreover, if the malfunction is accompanied by an illuminated Check Engine Light, this could signal a more serious underlying issue that warrants immediate attention to avoid further complications. Ignoring the problem could lead to increased strain on your leg muscles, resulting in discomfort during extended drives. Additionally, cruise control issues may be symptomatic of other vehicle problems, such as sensor misalignment or faulty components, which could escalate if left unaddressed. Therefore, while it may not be critical to fix the cruise control right away, timely repairs are advisable to ensure your safety, enhance driving comfort, and maintain the overall health of your BMW M5.
See what others are asking about their BMW M5. Get answers from RepairPal's community of auto experts and enthusiasts.
Read about related problems experienced by other BMW M5 drivers like you.