I am trying to trouble shoot the bed lift motor on our toyhauler; which recently stopped working. During this project, I realized I am seriously lacking when it comes to RV electric. Happijac - our lift manufacturer - recommended hooking the motor direct to 12v. Simple I thought. I found a black wire labeled Bat+. I then found a white wire labeled Bat-. Put the meter on them and got 15.3 DCV. I then attached them to the motor and got nothing, no movement. Concluded the motor was bad. Just in case, I attached another simple 12v device (a USB outlet I know works) to the same black and white wires - NOTHING?! What the heck??? I have another trouble shooting rig I keep in the camper that plugs into a cigarette lighter near our RV stereo. Plugged it in and checked it with the meter - 15.3 DCV. I ran the leads back to the bed motor, touched them to the red and black wires on the motor - BINGO, it runs. I have run this through my head, trouble-shot the wiring a bunch of different ways and cannot figure out my issue? What am I missing?

Weak fuse, poor connection somewhere

I think there may be a loose connection inside the motor.

The voltmeter draws very little current while the motor draws a lot of current. There is probably a high resistance connection in the wires you tried to use. Connect the motor to the wires and measure the voltage, but don't leave the motor connected very long.

Thanks for all the replies. There is a common thread to my problems/ignorance because I encountered issues previously when trying to wire LED lights under my awning. I tried to hook them into an existing light fixture on that side of the camper. The fixture had two wires - Black (hot) - and White (ground). When I wired the red from my LED light to the black, and the black from my LED light to the white - nothing. I thought the LED light was bad because the fixture bulb still worked, but not the LED?!. I then hooked the LED direct to the battery as a test - bingo, worked. I eventually abandoned wiring into the fixture (frustrated) and tied into some wiring near our RV stereo. LED works great This issue with the bed motor is the same deal. Whenever I try to tap into the white/black 12v wiring scenario, I fail. Obviously I am missing something.... And someone is likely going to have an answer to exposes me as the goofy novice I am :)

For good of the group, I will update this subject and hopefully it might help someone trouble-shoot in the future. I bypassed the entire power supply to the bed lift system. I used a different 12v power supply and wired it directly into the circuit board that feeds the Happijac bed lift. IT WORKED. So, something definitely happened to the 12v power supply that fed the system for the 6 years we have owned this this Forest River toy hauler. Although my meter indicates the original wiring is getting power to the circuit board that feeds the bed lift system, I suspect maybe the ground is loose somewhere. I have no idea how to identify where the problem lies. So, my plan for a permanent solution is still "in the works." My gut told me failure of a Happijac lift system component was likely the cause, but in this case the trailer wiring was DEFINITELY the cause.

RV Electric - I am obviously a novice | Good Sam Community

ThomasFour
Explorer
Jun 15, 2015
Tenbear, yes I did employ your suggestion. The ground wire fails when I apply appropriate power to lift the bed. So, somewhere there is a problem with the ground wire. No idea how to identify where. I could just bypass the ground wire near the bed lift and that would probably result in problem solved.
tenbear
Explorer
Jun 14, 2015
When you were trying to connect the awning LED lights did you try to reverse the polarity? LEDs are polarity sensitive. Are you sure the black wire is the positive 12v and the white is ground?

Also, did you try my earlier suggestion of measuring the voltage under load? (connected to the lights or the motor)
ThomasFour
Explorer
Jun 14, 2015
For good of the group, I will update this subject and hopefully it might help someone trouble-shoot in the future. I bypassed the entire power supply to the bed lift system. I used a different 12v power supply and wired it directly into the circuit board that feeds the Happijac bed lift. IT WORKED. So, something definitely happened to the 12v power supply that fed the system for the 6 years we have owned this this Forest River toy hauler. Although my meter indicates the original wiring is getting power to the circuit board that feeds the bed lift system, I suspect maybe the ground is loose somewhere. I have no idea how to identify where the problem lies. So, my plan for a permanent solution is still "in the works." My gut told me failure of a Happijac lift system component was likely the cause, but in this case the trailer wiring was DEFINITELY the cause.
ThomasFour
Explorer
Jun 12, 2015
Thanks for all the replies. There is a common thread to my problems/ignorance because I encountered issues previously when trying to wire LED lights under my awning. I tried to hook them into an existing light fixture on that side of the camper. The fixture had two wires - Black (hot) - and White (ground). When I wired the red from my LED light to the black, and the black from my LED light to the white - nothing. I thought the LED light was bad because the fixture bulb still worked, but not the LED?!. I then hooked the LED direct to the battery as a test - bingo, worked. I eventually abandoned wiring into the fixture (frustrated) and tied into some wiring near our RV stereo. LED works great This issue with the bed motor is the same deal. Whenever I try to tap into the white/black 12v wiring scenario, I fail. Obviously I am missing something.... And someone is likely going to have an answer to exposes me as the goofy novice I am :)
tenbear
Explorer
Jun 12, 2015
The voltmeter draws very little current while the motor draws a lot of current. There is probably a high resistance connection in the wires you tried to use. Connect the motor to the wires and measure the voltage, but don't leave the motor connected very long.
Dakota98
Explorer
Jun 12, 2015
I think there may be a loose connection inside the motor.
MrWizard
Moderator
Jun 12, 2015
Weak fuse, poor connection somewhere

Forum Discussion

RV Electric - I am obviously a novice

About Technical Issues

Related Content

Novice Question

Novice looking for an upgrade to Class C

Electric heating

Electric vehicles

electrical