While most wrecker disorders involve components that fail to operate when called upon to do so, there also exists a rarer, stranger type of problem:  one in which parts start to move by themselves when they're not supposed to, without anyone around.  For example, the wrecker boom will start extending by itself even though no one pushed the control lever.  In the manner of an Edgar Allan Poe story, some long-neglected condition that builds up unnoticed over time usually causes these "ghosts in the machine."

Self-operating wheel lift

One very cold winter morning two years ago, one of my customers walked out to his dually pickup with a hideaway wheel lift and found that the wheel lift had lowered itself to the ground overnight.  When the wheel lift hit the ground, the electric pump kept going and lifted the pickup's rear axle off the ground, immobilizing the pickup.  When I took apart the remote control, I found that rainwater had accumulated over time inside the plastic remote control box and the hard freeze of that morning had caused an electrical connection to be made in one of the switches.

Solve this problem either by drying the box and installing new switches or by getting a new remote control.

Out-of-control underlift

Spontaneous movement also happens in heavy-duty wreckers.  In a case which resulted in someone having to buy new tires for the towed vehicle, the driver of a 45-ton heavy-duty drove down the road doing a tow, unaware that with every bump in the road both the underlift tilt function and the three-stage underlift extend function went down and out a little, respectively.  I noticed the wrecker not only had manual control handles but also two separate remote controls.  One remote control consisted of hard-wired switches in the cab control panel and the other remote control was a detachable hand-held type that plugged into a female receptacle in the extreme rear of the wrecker bed.

I asked the driver if he ever used the hand-held one, and he said never.  It had hung in the toolbox unused for years.  I flipped open the cover of the female receptacle in the wrecker bed where that remote control plugs in and found that years of disuse and vibration had loosened the screws that hold the nine contact pins so that the pins briefly and intermittently touched each other with each bump in the road.

Although this problem can be solved by installing a new female receptacle, the problem can also be guarded against by plugging in and using the remote control periodically.