Snorkel TB42 Boom Functions Cut Out At Low Angle
Fault Codes & Symptoms
All boom functions (lift, extend, swing) stop responding when the main boom is lowered. Related symptoms: - Erratic boom angle display on the platform controls. - Inability to drive the machine at height (if platform is above a certain angle). The lift works fine to get up in the air, but once I bring the boom down, it just quits. I have to restart it to get it to stow. It only happens when I lower the boom pretty far down.
Confirmed cause: The wiring harness for the boom angle sensor had an internal wire break near the main boom pivot. The break would separate and create an open circuit only when the boom was lowered to a specific angle, causing the harness to flex in a particular way. Repair performed: Replaced the boom angle sensor harness with a new part. Ensured the new harness was routed correctly with adequate slack to prevent binding or chafing through the full range of boom movement. Verification: Cycled the boom from full height to the stowed position multiple times. All boom functions operated correctly through the entire range of motion with no cutouts. Technician notes: - The internal harness break was not visible externally. The sheathing looked intact. - This type of intermittent, position-based electrical fault is common on articulating and telescoping equipment where harnesses are subject to constant movement. - Using the service tool to graph the sensor signal while moving the boom was key to seeing the signal drop-out, as a simple multimeter check at a static position might have missed it.