MaxBrake Controller issue?

I have no experience with hydraulic trailer brakes other than surge brakes on a boat trailer.

You might try unplugging the sensor in the brake line and see if it still runs. If it does there is either pressure on the brake line when there shouldn't be or a bad switch.

Just a thought.

kwinterb wrote:
When I first had the MaxBrake Controller installed I never noticed any “excess noise” coming from my hydraulic brake setup in the 5vr. Then one day, I got out and heard what sounded like the hydraulic brake pump running on the 5vr.

Could have been there all the time and 'just' noticed it

My brake lights were not on but I pulled the cable and the noise stopped. This went on for a few trips happening intermittently. The trailer brakes seem to work fine and I’ve checked the hydraulic fluid reservoir in the 5vr and it is full. Now it seems to be happening always and I’ve found I can stop the pump from running by turning the adjusting knob down to zero, but of course that causes a problem when I am towing.

This tosses a monkey wrench into what I was thinking and will touch on
that below

So the current issue - When I am parked, brakes off and gain on zero, everything is fine, as soon as I barely start to turn the gain up, it engages what I am assuming is my hydraulic brake pump on the 5vr. When I turn it up, neither my truck or 5vr brake lights turn on, but when I engage the truck brake pedal, the lights work fine. Turing up the gain will also increase the intensity (noise) coming from the hydraulic brake pump. When I drive, I leave the gain just high enough to have the brakes work ok and when I stop after a while, the trailer brakes are not excessively hot as if I had been riding with the brakes engaged. So, where’s my problem?

Ken

First, I do NOT know much about hydraulic trailer brakes (other than
surge brakes), but have designed industrial braking systems. From
drum/shoe. Shoe moves inwards onto a drum that weighs in the hundreds
of pounds. Disc brakes were in the 48" dia range. Consulted with an
after market 'big' brake firm in S Calif and E Coast, both cars and
SUV applications

Assumption is that the trailer brake system has an accumulator for
quick response. That then has a pump run till a preset PSI is reached
(that has some margin for bleed off so that the pump will NOT run all
the time)

That variable 'dump' valve must be proportional and the brake controller voltage
is the control for that variable rate of flow/PSI

There is another potential design and is that the calipers are normally
'closed'. Meaning if power is lost, they close to squeeze the disc
and the hydraulic pressure is to 'open' them, or release the disc
That would then have the below valve normally 'open' and close when
power is applied


Again, my knowledge at this time for hydraulic trailer brakes is
limited. So I could be all wet in the above






MaxBrake, and assume MC PSI sensed with a gain adjustment. Since MC
PSI sensed, that gain only comes on when PSI is sensed, or does it
also sense the brake pedal switch? If so, then a MaxBrake can lead
the MC PSI just like my P3 can







Initially thought it was always there and you just 'noticed' it, but
that monkey wrench throws that off or out

Since the trailer hydraulic pump stops when you turn the gain down
to zero, it indicates a problem in the MaxBrake controller and/or
the sensor

Sensor in that it is not returning to ZERO PSI, but telling the controller
that there is some PSI. That can also be a bubble in that TV brake
line. It compresses during braking and when the brake pedal is released,
it will expand to keep a bit of PSI in 'that' brake line.

That is one of my comments of their instructions that lack completeness
or fastidiousness in design...not instructing to bleed that whole
line, but just the new 'T' and stub line

Or the controller is out of adjustment and/or is going south. Could
be the gain circuit or the potentiometer

Please post back when you find the root cause. Either back at the
trailer brake system or the MaxBrake control system

benk wrote:

Sensor in that it is not returning to ZERO PSI, but telling the controller
that there is some PSI. That can also be a bubble in that TV brake
line. It compresses during braking and when the brake pedal is released,
it will expand to keep a bit of PSI in 'that' brake line.

Forgot to mention that there is another issue, IMHO, with MC PSI sensed

That is with MC's that have more than one brake line

As any of the MC PSI sensed only sense

ONE

line

The reason today's MC's have more than one line is a fail safe design

If one line should be damaged, the other line 'might be' or 'should be'
still operational. Albeit only two wheel braking....never the less
braking of lesser degree

If the line that goes south is the one a trailer brake sensor is
on...no trailer brakes...

I think you should be calling MaxBrake customer support. They do have a 5 year warranty.

Thanks for all the info/tips everyone. Wow didn't realize a 5 year warranty was in place. I'll call them.

kwinterb wrote:
Thanks for all the info/tips everyone. Wow didn't realize a 5 year warranty was in place. I'll call them.

Let us know what the problem was.

Well, after re-reading the "manual" I decided to try and do the calibration step again. That seemed to do the trick. :)

My magnets were buzzing while parked, so I recalibrated the sensor and all is well now.

I think you are on the right track.