Using thermal imaging to diagnose an electrical fault

The interaction of volts, resistance, and current flow is what makes up the complex electrical systems we see in modern passenger and commercial vehicles.
Diagnosing a fault in any of these systems can be daunting, especially if faced with problems in control modules, wiring, or the increasingly complicated BUS network system.
Poor connections in any circuit cause an increase in resistance. A by-product of current flow through a resistor is heat – these are the basic elements of a light globe’s operation.
To take that a step further, imagine a body electrical harness connector that has suffered moisture ingress – the green corrosion you see acts as a resistor in the circuit, therefore creating heat.
The traditional way to pinpoint faults such as this would be to perform voltage drop checks across each conductor/connector until the source of the resistance is found. But Snap-on says there is a faster and much more efficient way.
Thermal imaging technology is quickly gaining a foothold in the automotive diagnostic hall of fame due to its ease of use and more importantly, the speed at which faults can be located.
Any electrical device in the vehicle is designed to operate at a given current flow. If the current flow were to dramatically increase (which may point to an internal short) the heat generated by the component would also increase. Using the thermal imager here would show the fault as an abnormal heat source.
A short circuit within a wiring loom could be located quickly by replacing the circuit fuse with a high wattage globe – then passing the thermal imager along the harness. The short will be visible as an unwanted heat source in the wiring – this is due to the current flowing through the bulb and tracking to ground across the short.
Parasitic drains can also be located very quickly. Switch the ignition off and allow all control modules to go to sleep. Then pass the thermal imager over the vehicles fuse box. Any current flow will be displayed on the imager screen as a heat source. Cross reference the hot fuse or relay with the vehicle circuit diagram to isolate the drain to a particular system.
The thermal imager can be used to pre-empt failure of a circuit or system by comparing captured images or video with a database or image library. If the component is producing excessive heat, the system could be inspected and repaired before outright failure occurs.
Snap-on encourages you to keep your workshop operations cost effective by adding thermal image technology to your diagnostic process.
To arrange a demonstration, speak to your local Snap-on franchisee.

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