Power Jack needs shore power?

[cp1977]

I have a 77 safari, The power tongue jack will not work on battery power, even with tow vehicle connected and running. Plug trailer into shore power, 15amp, and jack works fine. Jack appears to be directly wired from the battery to the jack. Batter was just charged and installed prior to trying to use jack. Any ideas on what is going on? It would be nice to be able to hitch and unhitch away from shore power. TIA
Lorry

[rmkrum]

Sounds like the battery is not holding any charge.... Time to get the voltmeter and flashlight out to see if there is water in it, and the state of charge. Sounds dead, Jim....

[cgseanp]

Is it possible that the jack isn’t making good contact with the frame and isn’t grounded? I had a similar issue, mine would only work intermittently but turns out it wasn’t grounded properly.

[uncle_bob]

Hi

On something as old as a '77, I would not assume anything is "stock". You never know what somebody may have done ( unless it's been yours the whole time ). The jack may be grounded to the frame. If not, trace out where it does ground. Most jacks wire power direct to the battery via a fuse. Wire or fuse could be faulty. Wire might also go somewhere else....

Checking the batteries and charging system is sort of independent of all this. If there is any reason to suspect the batteries ( like they are > 4 years old ), pull them and get them checked. Check the converter / charger as well. If it's original stock, consider replacing it. If it's an upgrade that is > 20 years old, consider replacing it. In both cases, you are on borrowed time until a failure. In .... errr .... some cases those failures can be pretty dramatic ( as in 24V on the 12V bus ..... I have data on this .... )

Lots of fun

Bob

[Air4563]

On my 75 I ran a wire directly from the negative post of the battery to one of the mounting bolts on the jack-after cleaning the contact artery of the bolt. Worked fine thereafter.

[kendrick.l.j]

My first thought was dead battery but I am sure that is the very first thing you checked. Ditto what Uncle Bob said....he’s much smarter than I am and been around Airstreams longer.

[steverino]

Could also be a poor/corroded battery terminal. When pulling a small amount of current, things tend to work fine, but pulling a lot, such as with the jack, drops enough voltage so the jack won’t function. The tell-tale for this issue is to disconnect from shore power, and turn on a light in the rig. If the light goes out when you try to run the jack, it’s likely either a shorted battery cell or poor battery connection, on either positive or negative terminal.

[cp1977]

I checked my battery, it is good, so the inverter is charging it. Then I checked my 12 v lights etc... nothing unless shorepower connected. no interior lights or anything. Not sure how to check the ground for the jack, doesn't seem to have a ground wire. No name on jack, also no manual operation possible as far as I can tell, when I pull the cap off the powehead all I see is a gear coming from the electric motor meshing with another gear on the jack leg. Not sure how to get inside where the motor is. But I think it is an issue with the 12v siystem, not the jack itself. I am not sure where to look for 12v issues, have to dig up my owners manual I guess. Thanks for the help...... Lorry

[fran&frank]

Yes it sounds like a problem between your 12V system and battery. Evidently battery power is not getting to any of your 12 Volt system but when plugged in your converter is powering the 12 V system. I would recheck all your battery connections, especially the ground.

[cp1977]

Checked fuses in 12v system. They looked good but on closer inspection the 50 amp fuae was sparking a bit inside. Swapped it out and now everything works. Thanks to all for the help. This shade tree mechanic couldnt do it without all the help here on forums. Lorry

[OTRA15]

Thanks for the update, good news!