Reverse Lockout Soleniod Installation Question

[thompsdw]

I recently added a reverse lockout soleniod (connected to my reverse light) install on my trailer boat. I spliced the soleniod into the brake line and ran the 12V line to a newly installed 7 prong plug on my auto.<br /><br />Here is what happened. At first the soleniod seemed to work fine with no problems. I was able to drive forward with no issues and was able to backup with no problems. Did this for a while and while driving down a steep hill I attempted to back up and the brakes locked up. After this, the brakes were locked in either direction. Basically, there was pressure behind the solenoid (brake side) that did not dissipate. I am assuming that the solenoid did not open back up. I bled the pressure off of the downstream side of the soleniod, cut the 12V supply line and went boating.<br /><br />I don't understand why the system worked normally and then suddenly locked up. The steep hill was the only factor that changed. Are these soleniods directional? There is no marking on the soleniod, however, the hill would have caused much higher braking pressure than previous. I was wondering if reversed, if this pressure could cause the valve to not open.<br /><br />I am clueless other than this theory. Please help.

 

[gutshot grouper]

Re: Reverse Lockout Soleniod Installation Question

Evidently the solenoid leaked or bypassed when you backed up the big hill, it is also poss. that the higher pressure damaged the valve body so that it could not flow when the 12v. was removed. I have a similar dilemma, I cannot find a small valve to put in line to shut off the brakes when backing. Those discs are real binders which won't let you back up. I drilled a hole in sliding tongue and put in a pin when I back which is just one more irritation assoc. with trailering.

 

[islandboat]

Re: Reverse Lockout Soleniod Installation Question

Sounds like something that the disc brake manufacturors discussed in a small note somewhere in the operation instructions. It's easy to miss that note but I do remember reading something about that with my disc brake system's instructions. Basically, if you stop fast or stop with the trailor uphill from the tow vehicle and brake apply pressure is trapped in the trailors brake calipers (which is normal operation), when you shift into reverse the brake fluid is trapped in the brake system and it will not let you backup. One cause of the problem can be resolved by stopping slowly if you know that you about to backup, or pull forward a few inches after stopping quickly to release all brake pressure in the trailors system ( on level ground). However that was most likely not the cause of your problem. It sounds like the reason for the problem you incurred was that the weight of the trailor, which was on an incline, pressed forward into the trailors master cylinder before you shifted into reverse and applied the lock-out solenoid. <br />After you cut the 12v supply wire, have you been able to back up normally? Usually it requires 12 volts to close the lock-out solenoid and prevent pressure from reaching the trailors brake calipers. <br />There is another setup for locking out the brake pressure when backing up. It is a solenoid that is inline with brake pressure, as you currently have, but it has a tube that routes the brake pressure/fluid back into the top of the master cyl when 12 volts is applied. Costs a little more, but it might be what you need.<br />Those disc brakes really hold good in reverse, don't they.

 

[jk1162]

Re: Reverse Lockout Soleniod Installation Question

YOY HAVE WHAT IS KNOWN AS A BLOCK OUT VALVE. THE DRAW BACK IS THAT IF YOU DO STOP GOING DOWN HILL AND TRY TO BACK UP YOU WILL STILL LOCK UP THE BRAKES BECAUSE THERE IS ALREADY PRESSURE ON THE BRAKES. THE BEST BET IS TO CHANGE TO THE BYPASS VALVE AS MENTIOND ON THE LAST POST. IT REQUIRES YOU TO DRILL AND TAP AN ADDITIONAL HOLE IN THE MASTER CYLINDER WHICH LETS THE PRESSURE BACK INTO THE MASTER CYLINDER.