Repeated Rear Camera Failures on a Wheel Loader, Central Texas (2020)

In 2020 an equipment manufacturer asked us why the rear camera on one of its large wheel loaders kept failing at an industrial site in Central Texas. The client and the site are not named.

A small part with a safety job

On a machine that size, the rear camera is how the operator sees what is behind the loader. Replacing the camera had not solved anything. The real question was whether the cameras were weak or something on the machine was damaging them.

Measuring the circuit while it ran

The loader was parked in a lot at the site for our examination. We took the camera out of its circuit and measured the data and power channels while they were energized, using a motor drive analyzer and a digital multimeter. The data channel looked normal, with only routine attempts to communicate. The power channel supplied about 8 volts DC, but random high frequency spikes of roughly 4 volts rode on top of it.

Next we disconnected the camera and the controller supply and measured the primary power system of the machine. It held steady at about 22 volts, with nothing beyond ordinary noise, so the spikes were not coming from the machine supply. With the harness and controller connected again, the spikes came back. When we gave the harness a brief tug, spikes appeared at the same moment.

What it pointed to

Spikes that follow movement of a harness point to damage in that harness: an intermittent short that switches at high frequency. Over time that stresses the power regulators inside the camera until they fail, and it can wear on the camera controller as well. We recommended replacing the camera harness and suggested that devices with high speed communication run on a harness of their own, so damage in one bundle cannot short across systems. The camera and controller already installed might be partly damaged. We measured no abnormal fluctuations on the other powered systems of the machine.

Mobile equipment

Heavy equipment vibrates, flexes and gets washed down, and its harnesses take the worst of it. When one component keeps failing, measuring the circuit that feeds it usually tells more than another replacement part. Measurements like these are routine in electrical failure analysis.