Many RVers love the ease of a power tongue jack over the physical cranking of a manual tongue jack. However, the downside is having an additional electric motor with an added risk of failing.
If your travel trailer has a power tongue jack, you need to know how to troubleshoot it. Let’s explore simple checks you can do yourself and identify when you’ll know to take your RV to a service center.
Check for Power to the Tongue Jack
Most tongue jacks have a light that displays when there’s power to the unit. Ensure the switch is turned to the ON position and check that the light turns on. However, that small light only requires a small amount of power. The electric motor requires more power to operate the tongue jack.
So, if you turn the power tongue jack’s switch to the ON position and the light doesn’t come on, you potentially have two issues. Either the bulb has simply burnt out, or the unit isn’t getting enough power.
It’s easiest to check the status of the latter first. Do so by checking the operation of other 12-volt components, such as your interior lights or power awning. If those components aren’t working, there’s a good chance you have a dead battery.
If they are working, but your power tongue jack won’t extend or retract, it’s possible it’s simply not getting enough power. So you can move on to the next check to determine if a lack of power is your major issue.
Plug into your Tow Vehicle
Next, you can plug your trailer’s 7-pin connector into your tow vehicle and start its engine. This will pull power from the alternator through the charge feed line to power the tongue jack.
If this works, there are a few issues that could be present:
- The battery that powers the tongue jack isn’t being charged in transit.
- The converter isn’t charging the battery.
- The battery has been discharged so fully that it’s no longer taking charge.
If the power tongue jack works when connected to your tow vehicle but no longer operates once you disconnect, move on to the next check.
Check the Power Tongue Jack’s Fuse or Mini Breaker
Most power tongue jacks have a single power cord running from the head of the unit down and along the trailer frame to a mini breaker or fuse. There’s only a single cord because the unit is grounded through the bolts into the frame.
Follow that power cord down and back until you locate the fuse or mini breaker. If you find a fuse, pull it and check that it isn’t broken. If it is broken, replace the fuse with one of equal amperage.
Trace your power cord back. If you locate a mini breaker, you’ll need a multimeter for testing. With your multimeter in hand, here are your testing steps:
- Ensure the battery is fully charged or the trailer is connected to a running tow vehicle. A fully charged lead acid battery should read 12.6 volts DC, and a fully charged lithium battery should be around 14.4 volts DC.
- Set the multimeter to the Volts DC setting.
- Test by placing the negative lead on a known ground and the positive lead on the BAT side of the breaker to confirm power to the breaker.
- Test again by keeping the negative lead on a known ground and moving the positive lead to the AUX side of the breaker.
- Compare the readings to confirm power passes through the breaker with minimal drop. Most tongue jacks should work at voltages above 10.6 volts DC as measured while the jack is running.
- If testing properly and finding a significant power drop from the BAT side to the AUX side, you may need to replace the breaker.
Technician Tip: The BAT label designates the stud for your power connection. The AUX label designates the stud for connecting the auxiliary device the breaker will protect.
When It’s Time to Take your RV to a Service Center
If you’ve eliminated issues with your RV’s 12-volt system – battery charge, converter output, breaker output – you may be dealing with an electrical or mechanical issue inside the power tongue jack.
Some common examples include loose internal spade connections, faulty switches, or a failed motor.
Regardless of the exact cause of the problem, it’s time to bring your RV into a service center to have your tongue jack inspected.
How to Manually Operate a Power Tongue Jack
With your appointment time scheduled, you’ll still face the challenge of retracting your tongue jack to tow it safely. You’ll need your jack’s manual crank handle to accomplish this.
With that crank in hand, here are your next steps:
- Remove the rubber cover on top of the tongue jack. *Some jacks have the manual crank spur on the side.
- Insert the crank handle onto the top of the driveshaft and turn counterclockwise to retract the jack leg. Reverse direction if you need to extend the jack for any reason. *Some jacks crank counterclockwise to extend.
If you experience significant resistance or your tongue jack simply won’t move when attempting to operate it manually, you could have a more significant mechanical failure. Examples include a bent ram tube that prevents the jack from sliding into the housing tube or a bad thrust bearing or bevel gear inside the unit itself.
Technician Tip: When experiencing a failure to retract, soil, gravel, or asphalt may have compacted inside the tube if a jack foot was not used. This can be chiseled out with a hammer and a long screwdriver while the unit is elevated on a jack stand. If the jack is difficult to operate in either direction, you may be able to remove the top cover or cap to expose the main shaft. Applying lubricant may restore functionality.
Beyond lubricating to restore functionality, more significant mechanical issues aren’t repairable, and you’ll need to replace your trailer’s power tongue jack.
Here are a few more resources to help you troubleshoot other parts of your RV:
- Troubleshooting RV Circuit Breakers
- Troubleshooting RV Converters and Inverters
- Troubleshooting RV Batteries and Trailer Lights
Stumped with a power tongue jack issue? Drop us a comment and we’ll get back to your ASAP.