Electric Brake Wiring

Electric Brake Wiring - No No's!

This is a bit of a horror story, but one which should be checked out by all A'van owners in case their car has been wrongly fitted. At worst your brakes could fail or your vehicle catch fire. We were doing an A'van Makeover - a bit like Changing Rooms on Siggy's A'van and Subaru Forester. One of the five projects was fitting a cable from the battery to the rear of the car so that the fridge could run on 12 volt with the car moving - works great by the way - we held 3 degrees during that dreadful hot spell Xmas 2000. On lifting the bonnet we noticed that the auto reset overload had been wired with 4mm wire instead of 6mm.

The cable completely melted through the sound insulator

The correct wire in the photo above is being held by hand so you can spot the HUGE difference. The installation had been done "professionally" at considerable cost. Siggy was at Bear Gully with us Xmas 2000, and had been plagued with intermittent electrical problems with the Forester - pretty rare normally as these cars are beautifully made.

We removed the complete boot of the Forester to allow us to run the fridge cable neatly and safely. We found the molten mess as shown in the picture above and right! (cable on the left) Brakes can take 20+ amps and the cable used was only 10 amp. The result was lots of heat. We were just lucky to spot this before disaster struck. Main brake cables are not fused. The control box is. They go through what is called a self resetting 20/30AMP overload relay. This drops out on overload and then comes back on automatically as soon as it cools. The driver has no idea at all if this is being actuated. We are thinking about putting a couple of small LEDs on the dash which glow when current is flowing. (one for fridge, and one for brakes) What would happen then is, they should blink if tripping during brake application. A'vans by the way are fitted with the best brakes money can buy! Siggy used a Tekonsha Voyager controller. You can find heaps of information on their site BUT sadly nothing on cable size! We strongly urge all A'vanners to check if their wiring is 6mm diameter or larger.

It is easy to spot the wiring for checking yourself on any make of vehicle. Look near your battery for a small metal box with two threaded screws on top (auto reset overload). The photo shown is on a Forester where we mounted an overload for the fridge and brakes side by side in a convenient spot near the windscreen washer bottle. Siggy's is near the battery - a bad spot because if you need to get a bigger battery in and out in the future it could be in the way. Warning: Overloads MUST be kept well away from manifolds to avoid "phantom" tripping. More info email or read the extensive information on brakes in the DIY section of this site.

Bob & Chrissy Eustace