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Power, protection and controls

A slide needs full battery voltage at the motor or controller while the room is moving, not at rest. Prove the feed and the ground under load, starting at the battery, before you condemn a motor or a controller.

The short version

The feed from the battery

Lippert's numbers are consistent across its electric slides: 10 gauge wire minimum and 30 A of protection. The in-wall owner's manual calls for a 30 A resetting or blade fuse (OEM supplied) and at least a 30 A circuit breaker. The motorhome electric slideout manual shows a 30 A auto-reset breaker within 18 in of the battery. If a new breaker trips immediately, Lippert says the wiring to the controller has a fault.

The ground is half the circuit. Lippert's through-frame, hydraulic and Above Floor manuals require an independent ground wire back to the battery, recommend a star washer at the chassis connection, and say over 90% of unit electrical problems are bad ground connections.

On a motorhome, find out which battery the slides run from. Owners report that on some Winnebago coaches the slides and step run off the chassis battery, so a full house bank doesn't help a low chassis battery.

Switches, relays and controllers

Simple electric through-frame and Above Floor systems use a reversing wall switch that feeds the motor directly. Lippert's fix for a room that runs backward is to swap the motor wires at the back of the switch. That switch carries full motor current, so a burnt contact is a real failure.

Controller systems (in-wall, SlimRack) use the switch as a signal. Lippert's in-wall manual wires the common on the control board to the common on the extend/retract switch. The controller does the switching, watches voltage and current, stops the motors at the end of travel and flashes codes.

Hydraulic systems switch a pump relay and valves. HWH's list for a pump that won't run when the room switch is pressed: park brake not set, a bay door open under the room, a blown fuse, a poorly grounded pump relay or pump, no 12 V to the pump relay, or a wiring fault at the room switch or bay door switch.

Multiplex and OneControl

On multiplex coaches the switch may be a screen. Tiffin's 2019 Allegro Open Road runs its slides from the Spyder control system, with rocker switches on the driver's and passenger's seats for the front slides. Lippert OneControl coaches can run slides from the touch panel or the phone app.

On these coaches the button press goes through the multiplex system before it reaches the slide, so 'the screen won't move the room' isn't a slide fault until you've proven the command gets out. Pull the OEM wiring diagram, find the slide output, and test it while someone presses the button.

Test the circuit under load

A meter on an idle circuit tells you almost nothing. A corroded lug or a few strands of wire will show full battery voltage with no current flowing. Read voltage where the slide gets its power, with the room moving.

  1. Read battery voltage at the posts with the room at rest.
  2. Put the meter on the controller power junction (in-wall: the red and black terminals) or on the motor leads, and have someone run the room.
  3. Read the battery posts while the room runs. If the battery itself sags hard, charge or replace it before going further.
  4. Compare the two running readings. A big difference is drop in the feed or the ground.
  5. Split it: battery positive to controller or motor positive while running (feed side), then battery negative to controller or motor ground (ground side). Fix the side that reads.
  6. On a direct-switch system, check 12 V at the switch terminals, then at the motor leads with the switch pressed. Lippert: 12 V at the motor and no movement means the motor.

Why charge it or plug in first

Every Lippert slide manual starts troubleshooting at the battery. The motorhome service manual says not to troubleshoot the motor without a full 12 V DC charge: batteries fully charged, or the unit on AC power with batteries installed. Lippert also notes that slide motors draw considerable current and that shore power helps supply it.

Low voltage looks like other faults: a slow room, one side lagging, low battery or battery drop-out codes, a stall partway. Lippert's through-frame chart lists low battery, a poor ground and extremely low outdoor temperature as the causes of a motor that runs but moves the room slowly. The in-wall controller runs from 8 to 18 V but draws more current as voltage falls. Get the voltage right and retest before you diagnose anything else.

If you have to jump a dead battery to bring a room in, Lippert says connect directly to the battery and never to the controller power connections.

On the job

  1. Ask what the room did (dead, slow, one side, stalls) and note the controller LEDs or codes before you touch anything.
  2. Check battery voltage and charge; charge or plug in with batteries installed before testing.
  3. Find and check the breaker or fuse near the battery and at the controller. A new breaker that trips immediately means a wiring fault.
  4. With the room moving, read voltage at the controller power junction or motor leads and at the battery.
  5. Split any drop into feed side and ground side, and clean or replace the connection that reads.
  6. Check the switch: 12 V at the switch junction for extend and retract on controller systems, or 12 V through the switch to the motor on direct systems.
  7. On multiplex coaches, prove the slide output from the panel before blaming the slide.

Numbers

Shop tip

Clip the meter to the controller power junction and tape it where you can see it from outside. One person on the switch while you watch the room and the meter together beats three trips around the coach.

Where this comes from