Avant 528 won't start? Check the aux hydraulics lever first

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The symptom

You climb on, turn the key, and nothing happens. No crank, no cough. The dash lights may well come on as normal, which makes it worse: the machine looks alive and simply refuses to do anything with the starter.

The instinct is to go straight to the battery, then the terminals, then the fuses. On my 528 that instinct has been wrong every time, and the real cause has been a lever I hadn’t touched.

The interlock

The 528 will not start while the auxiliary hydraulics flow is switched on. It is a safety feature: if the aux circuit is live at the moment the engine fires, whatever attachment is on the front starts moving immediately (a rotating brush, a log splitter, a grapple closing) with nobody’s hands on the controls yet. So the machine insists the flow is off before it will crank.

The manual says it in one line: “The engine cannot start if auxiliary hydraulics control lever is in locking position”, and the starting procedure begins with making sure the lever is in neutral. The same manual covers the 520, 523, 528 and 530, so every 500-series machine has it (500 Series operator’s manual, starting the engine).

Flip the lever back to off, turn the key, and it starts as if nothing was ever wrong.

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Why it keeps happening if you have kids

Mine love to sit on the Avant when it is parked and switched off. It has levers, pedals and a seat at exactly their height, and the aux hydraulics lever is the most satisfying thing in the cab to move. Nothing happens when they move it — the engine is off — so they leave it wherever it ends up.

The next time I want the machine it won’t start, and because I didn’t touch the lever I don’t think to look at it. A quick walk-around doesn’t show anything either: the lever is not obvious from outside the cab, and the machine otherwise looks exactly as I left it.

If your Avant does start but the dashboard has stopped telling the truth — dead rev counter, warning lamps that never light, gauges that react to the diff lock — that was one faulty relay on my 528.