Electrical Resistance test on van 7 pin plug

[Fallen]

Hi all. My electric brakes have been working fine for a long time, but yesterday I noticed that the brakes seemed to stay energised when I got out of the car with no brake pedal pushed. I have the Tow Pro Elite and know it has a park brake function so thought it might be that. Then when driving it seemed as though the van brakes would apply without me pressing the brake pedal - all I needed to do was turn the brake controller dial to a higher setting (not press it).
I did the globe test on the car and it works perfectly, so wanting to test the van plug. What resistance should I be seeing on the electric brake pin for a dual axle? I'm measuring 1.3ohms at the moment. With nothing connected this is what I get so far:

1 Left Indicator 11k ohm
2 12v 5.3k ohm
3 Ground (ground to chassis is 0.5 ohm)
4 Right Indicator 11.5k ohm
5 Electric Brakes 1.3 ohms
6 Stop Lamp 9.2k ohm
7 Tail Lamps 3.8 ohm

 

[Drover]

Multi meter in hand, check that the breaksafe isn't leaking into the circuit, check at the junction by the brakes, it should read zero, if it shows anything check the pin on the draw bar, then plug into the tug the test should again read zero at the wheels if it shows up some voltage then its either a short in the 7 pin or controller.............., Volts can be from 8 -13v depends on what the controller is set at but when foot on pedal, no foot no power.

Resistence on the brake magnets I think its somewhere between 3 and 4, too little or too much the magnet is suss, one wheel dragging coulld be nagnet or the swing arm has bent, all wheels dragging usually points to controller fail or breaksafe.............. unless you have ESC fitted then thats another can of worms which can cause brakes to stay on....

Checking magnets mean disconnecting the wires at each brake then doing the resisitance test on the individual magnet......

 

[jazzeddie1234]

Assuming 4 ohms each (which is pretty close) I would expect to see just over 1 ohm at the plug. Just turning a setting for the brakes to apply sounds like a controller thing whereas a brake that won't release easily after application sounds a bit mechanical and a random application sounds like what Drover suggested, some form of leakage from breakfree or electronic sway controllers or a 12v feed - either a fault in the unit or a frayed wire

 

[Boots in Action]

Assuming 4 ohms each (which is pretty close) I would expect to see just over 1 ohm at the plug. Just turning a setting for the brakes to apply sounds like a controller thing whereas a brake that won't release easily after application sounds a bit mechanical and a random application sounds like what Drover suggested, some form of leakage from breakfree or electronic sway controllers or a 12v feed - either a fault in the unit or a frayed wire

Great response @jazzeddie1234 as you covered ALL the possibilities for @Fallen to check and eliminate one by one. Start with the easy one - mechanical as the electrics take some careful checking, disconnecting and reconnecting different circuits. I don't like the sound of unknown changes when brake controller setting is touched . Replacing a faulty brake controller would be expensive. But it could be as simple as a loose wire/bad connection??

 

[Drover]

Well enough of the theory, I'm a practical fella, using pin5 and the earth pin mine showed 1.6. while at an individual magnet, unplugged of course I got 3 or 9, it couldn't make up its mind, after I plugged it back in and crawled from underneath I realised the hand brake was on so thats certainly going to change the flow, not going back under though (magnets are near new)..... I doubt if a resistence reading from the 7/12 pin would be very indicitive of a fault as wiring size, condition of connectors and if ESC is fitted or not would cause numerous variations... I'd be mor einclined to see if the line is live without foot on brake.
If all brakes are dragging then its Controller/ESC/ BreakSafe bleeding into the system OR you have a hairy wire in the plug shorting into the brake set....it has happened............. If only one or 2 dragging then poor adjustment only one the activation arm could be bent.......