Electric trailer brake maintenance

Leave it for long enough and you’ll have trouble, not just with inadequate trailer brakes but a whole world of hurt if you crash because the brakes were not up to scratch.

Related stories:

Trailer brakes are a mandatory safety item for most boat trailers, and those that weigh more than 2000kg will also need a breakaway system.

The trailer brake system we’re looking at here is the most popular for large, 2000kg-plus boat trailers – that is, electric over hydraulic.

The trailer brakes are activated when an electrical signal is sent via the electric brake controller in the tow vehicle to a control unit on the trailer. Electricity, again supplied by the tow vehicle, then activates the pump that applies hydraulic pressure to the disc calipers at the wheels.

This is a simple system to maintain; and remember that hydraulic fluid should be flushed every two years if not sooner as it absorbs moisture.

Moisture can create havoc in a brake system, corroding pipes and ruining seals.

Brake pads should also be periodically checked for wear and disc rotors also for corrosion, scoring and thickness.

Washing down the brakes and brake lines with fresh water will help keep corrosion at bay.

Breakaway brakes are a legal requirement for trailers weighing more than 2000kg.

Aside from a control unit and a battery to power the breakaway brakes, there’s a pin box fitted to the trailer frame with a looped steel cable that attaches to the tow vehicle.

If the trailer comes off the towball and the safety chains also fail – in one recent incident the yoke linking the trailer to the tow hitch sheared – the cable/pin assembly attached to the tow vehicle pulls out of the pin box in the trailer frame, which closes the circuit for the breakaway brakes to activate the trailer’s electric brakes and also apply the trailer’s brake lights.

There’s a pretty simple way of checking that your breakaway system is functioning properly.

Hitch up the trailer and make sure that the breakaway battery is fully charged (the breakaway system's battery will start charging as soon as you plug the trailer into the tow vehicle).

Once fully charged, unhook up the trailer plug; this test is to partially simulate the trailer completely separating from the tow vehicle, and of course the plug will separate in such a situation.

Disconnect the breakaway pin from the pin switch by pulling on the cable that's normally attached to the tow vehicle. This will take a fair bit of effort and you’ll hear it as it disconnects – this is normal.

Now jump into your tow vehicle and try to gently drive forward. The trailer may move forward a little as the brakes activate, but you should meet strong resistance so that the trailer doesn’t move easily.

That means the breakaway system has activated. It should remain activated for at least 15 minutes, so turn off your vehicle and try again after about 13 minutes.

If the brakes did not come on with this test or didn’t stay on for 15 minutes, re-fit the pin and re-test.

If you still have no luck you need to get your brake system investigated further to see what the problem is – it could be brakes out of adjustment or a faulty battery. Make sure to re-fit the breakaway pin after testing.

Breakaway brakes checklist