Troubleshooting Electric Tongue Jack That Lights Up But Won’t Extend or Retract  

Question:

Expert Reply:

Your power issue could be due to one or more of a number of potential causes. These could include loose/corroded battery cables, batteries that need a good long charge with an AC-powered charger like # CTEK56353 to top them off, batteries that can no longer take a full charge due to age or a bad ground at the jack mounting plate.

Very often the cause for this kind of issue is the ground between the jack mounting plate and the mating surface on the trailer. Water and dirt can find their way in there and cause corrosion that will block a good ground connection. Even a bad ground there will usually pass enough current to operate the jack's light even though the motor will not operate.

A powered tongue jack's built-in lights use very little power to operate, a tiny fraction of the power needed to operate the jack motor, especially when they are efficient LEDs as on your jack. This means that the battery (or batteries) on the trailer will almost always have enough power to make the jack's light work even if they can't deliver the current needed to operate the jack motor. Your particular Stromberg Carlson jack # JET-3555 needs a full 30-amps to operate under load.

The fix is to remove the jack and sand off both the bottom of the jack mounting plate and the top of the trailer mounting surface. You want to expose clean bare metal on both parts and apply dielectric grease # 11755 before you reinstall the jack. In many cases like yours this is all that is needed.

If that does not restore jack operation then I suggest having the batteries checked. Deep cycle batteries are usually good for up to 200 charging cycles but they must be re-charged as soon as possible. If your batteries were stored for the off-season in a depleted state (without first being fully charged) then their lifespan may be over and they'll need to be replaced.

expert reply by: Adam R

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