Is your Bulb warning on the dashboard lit up but all your vehicle lights seem to be in working order? If this is a situation you are experiencing, it is most likely related to something called circuit resistance.
What is circuit resistance?
Simply stated, resistance is a measure of the opposition to current flow in an electrical circuit. Given that definition, a circuit with higher resistance would have lower current flow. And vice versa, a circuit with lower resistance should have higher current flow.
How does this concept apply to the lights in your vehicle? Well, the module that monitors and controls your vehicle lamps is looking at the current flow through each lamp circuit. If the flow is disrupted or changed by some other factor and is out of specification, it will display the Bulb warning. This could mean that the light is still working but there’s an indication of something causing a current flow issue.
What are some factors that increase resistance and lower current flow?
Some of the more common reasons your lights may experience circuit resistance issues may include:
- A faulty or inferior bulb
- Corrosion or dirt in the lamp assembly
- Overheating or faulty wires
How does a technician identify the circuit resistance issue?
One of the first steps that a service professional will do is to isolate the circuit that is having difficulty. This is done with computer diagnostics and gives the technician information on the affected circuit. From there, a seasoned service professional will use deductive skills and experience.
Some key questions they may ask, include:
- Is there corrosion at the lamp and connectors?
- Is the plastic bulb socket melted?
- Do the lamps use a brass base or nickel base?
Answers to these questions along with a careful inspection of parts is how a professional will be able to detect the source of the problem.
Example: The photos below were taken of a BMW with circuit resistance issues that resulted in a Bulb warning light but none of the lamps were out. Additionally, the technician determined that the sockets were clean, there were no signs of overheating, and the vehicle used nickel based bulbs.
A close inspection of the bulbs reveals the problem. Inside the bulb there is some melting of the filament carriers yet the filament is still intact which means the light still works.
In this particular case, the melted filament was the problem and it was the opinion of the technician that the bulbs were of inferior quality. For us at Shade Tree Garage the quality is of critical importance to keep our customers satisfied and prevent these annoyances.
If you are experiencing any issues with your lights, contact us today at Shade Tree Garage to schedule an appointment. We will examine your electrical circuits and identify any possible issues.