2004 BMW 745Li Electrical System Diagnosis Cost

The electrical system of a vehicle encompasses numerous components of multiple systems which function together or separately. These systems can range from engine or transmission control systems to entertainment systems. Since many systems are interdependent, the failure of one system which is seemingly unrelated to another may share common faults. That being the case, the electrical system of the vehicle must be properly maintained, protected, and kept in good repair. When faults do arise in the electrical system, a thorough inspection of the electrical systems affected by the fault will likely be required.

The electrical system begins at the battery for every vehicle. The battery sends electrical power to the entire vehicle either using one of many control modules or directly. These control modules or independent components communicate using mainly electrical signals, and these are transmitted over a wired network within the vehicle. This allows most control units in the electrical system to understand what is happening elsewhere in the vehicle, and use that data to control separate functions. This creates an interdependent electrical system which is complicated, but gives many clues to a technician upon an inspection or test.

Due to the nature of electrical systems on modern vehicles, the range of problems these can cause are nearly limitless. However, there is a way to categorize them in two ways. Permanent and intermittent problems. Permanent problems appear and remain. This may be the vehicle will not start, the radio does not work, or the door chime will not turn off among many, many others. These problems are more straight-forward to diagnose since they present themselves at all time. This means there will always be a fault to find. Intermittent electrical problems, however, can be difficult or impossible to locate, since they appear then disappear without warning. The best case scenario for an intermittent issue is when replicating the problem is easily accomplished and understood. This allows a technician to make an issue semi-permanent, allowing them to find the fault. Other issues that come and go without warning and cannot be replicated on demand must occur when the technician is servicing the vehicle, otherwise there is no problem to correct. It is most important to understand that electrical system faults always require inspection, and can include the vehicle working in any manner, or not working at all.

When dealing with electrical issues, the symptoms will determine the urgency, however, many electrical issues can cause further damage, so if additional symptoms begin to appear, even the smallest issue should be inspected. For issues that only pertain to comfort features, do not inhibit drivability, reliability or safety features, those issues can wait unless they begin to affect other components. If the problem does affect one of those three areas, however, it should be tended to right away. It may be unsafe to drive a vehicle with some electrical issues, or the vehicle may become undrivable.

Electrical problems can happen at any time, so inspection will be sporadic where malfunctions are concerned. However, many vehicle manufacturers specify inspection of some electrical systems and wiring harnesses when the vehicle is in for maintenance. Though there is no guarantee of when electrical problems will happen, most vehicles experience these issues after several years of use.

Electrical system issues are diagnosed through often painstaking and rigorous testing. Especially when it comes to intermittent electrical issues, electrical issues are seldom easy to solve, and they often require testing the entire electrical circuit involved. Technicians rely on years of experience and classroom training to understand automotive electrical systems and computerized controls. They may use multi-meters, factory diagnostic software, test lights, resistors, external power sources, and many other specialty tools in order to find the cause of an electrical issues.

Correcting electrical issues may require a variety of procedures, but commonly the battery will be disconnected, obstructing trim will be removed, and the faulty wiring or components will be separated from the main wiring harness to be replaced. Often it is necessary to remove corrosion and dirt from connectors in order to establish a good connection, and testing once the repair is complete is mandatory. Electrical problems can be located in any part of the vehicle, and significant disassembly may be required in order to facilitate repairs.

We recommend seeing a professional when electrical issues arise, especially if it is not abundantly clear what is causing the failure. In many cases, intermittent electrical issues will need to see an automotive electrician or diagnostic specialist, so bringing a complicated to any non-certified mechanic is not likely a good course of action.

Many vehicles with difficult electrical issues may need a diagnostic specialist to identify the cause. Many repair facilities would rather send the vehicle to a specialist than spend copious amounts of shop hours or customer costs on an issue that will require extensive diagnosis. There are specialty diagnostics shops that solve these problems regularly, and the most likely problem type is an intermittent electrical issue.

Electrical repair beyond fuses, obvious wire damage, dirty connectors, and bad relays should be left to a professional. These systems are highly complex, and technicians spend years in classroom and hands-on training to learn the skills necessary to accurately and properly diagnose an electrical issue on modern vehicles. Also, understanding of electrical circuit diagrams and components function is required in many cases, and should not be attempted without specific electrical systems training.