Safety first
- • Disconnect power at the panel before wiring.
- • Verify de-energized with a meter.
- • Follow local code — licensed electrician where required.
- • Always check the manufacturer's manual for your exact model.
GEM Remote wiring guide (GR1 / GR2)
What goes where on a GEM Remote receiver — for single-motor lifts, the common 3-motor cradle lifts, and 4-motor builds. Always confirm against the diagram inside the lid of your specific GEM box, since revisions vary.
What is a GEM Remote?
GEM Remote is a family of RF remote-control receivers used on residential boat lifts. The two you'll see most often are:
- GR1 — single-motor receiver. One UP / DOWN channel. Common on small single-motor cradle and PWC lifts.
- GR2 — multi-motor receiver with built-in contactors. Sized for 2-, 3-, or 4-motor lifts running on 115V or 230V single-phase.
Both work the same way: the handheld sends UP or DOWN, the receiver closes the matching contactor inside the box, and power goes out to every motor through the same leads. There's no "per motor" channel — all motors run together.
Power feed (L1 / L2 / GND)
Bring the feed from the landside breaker panel into the LINE side of the GEM box. The terminal block is usually labeled:
| Terminal | 115V hookup | 230V hookup |
|---|---|---|
| L1 | Hot (black) | Hot 1 (black) |
| L2 / N | Neutral (white) | Hot 2 (red) |
| GND | Equipment ground (green) | Equipment ground (green) |
Bond GND to the lift's main beam. On a 4-motor build, 230V is strongly recommended — the inrush on four motors at 115V can sag the supply enough to chatter the contactors.
Motor wiring — all configurations
On every GEM build, all motors connect in parallel to the same UP / DOWN / COMMON terminals on the receiver. You're not running a separate cable to each motor from a different output — you tap each motor into the same set of output leads.
Output terminals on a GR2
| U / UP | Goes to motor lead that spools cable UP (typically T5 on Marathon, BK on AO Smith) |
| D / DN | Goes to motor lead that spools cable DOWN (typically T8 on Marathon, RD on AO Smith) |
| C / COM | Motor common (T1 / T4 tied together, white) |
| GND | Motor frame ground (green) |
1-motor lift
One motor, four wires home-run from the motor junction box to the GEM: UP, DN, COM, GND. Land each on its matching terminal. Done.
2-motor lift
Both motors get the same three power leads in parallel. Splice motor #1's UP wire and motor #2's UP wire together, land on GEM U. Repeat for D and C. Both motors run together, in the same direction, every time.
3-motor lift (most common cradle lift)
Same parallel pattern with three motors. Use a watertight junction box at the lift, land all three motors' UP leads on a single bus, all three DOWN leads on another, all three COMMONs on a third. Run three wires (plus ground) back to the GEM:
- Bus UP → GEM U
- Bus DOWN → GEM D
- Bus COMMON → GEM C
- All motor frames bonded → GEM GND
4-motor lift
Same pattern, four motors. Run this on 230V, not 115V. Total motor current at 115V can exceed the GR2's contactor rating and will pop the dock breaker on start-up. Wire size up the run from the panel using the voltage drop calculator — #10 AWG is usually the minimum on a 4-motor run of more than ~75 ft.
Limit switch hookup
GEM receivers have a low-voltage limit input (often labeled LIM, UP-LIM, or a pair of terminals jumpered from the factory). A normally-closed beam-mounted switch on the waterside main beam wires into these terminals — when the lift hits the top, the switch opens, the UP contactor drops out, and travel stops.
- From-factory jumper between the limit terminals: remove it before landing your switch wires.
- Use 2-conductor low-voltage cable along the beam. Stainless staples, no kinks.
- Switch must be wired normally closed so a broken wire fails safe (lift stops).
For TEC-style beam combo switches and TEC's internal rotary cam, see the Set the lift limits page — the wiring concept is the same on GEM, only the terminal labels differ.
Wrong direction? Don't swap L1 / L2
If you press UP and the boat goes down, the fix is at the motor leads, not the line side. Power off, then swap the two leads that flip rotation on your motor brand:
- AO Smith / Electra Gear / Elite: swap motor BK ↔ RD
- Marathon / GE: swap motor BK (T5) ↔ RD (T8)
- Leeson: swap motor T5 ↔ T8
On a multi-motor lift, do the swap at every motor — they all need to spin the same way. Never swap L1 and L2. On a single-phase motor that won't change direction and only confuses other wiring.
Pairing the GEM handheld
Most GEM receivers ship pre-paired to the included handheld. To pair a new or spare handheld:
- Power up the receiver.
- Open the receiver lid and press and hold the LEARN button until the indicator LED begins to blink.
- Within ~10 seconds, press UP on the handheld you want to pair.
- The LED goes solid for a moment to confirm. Close the lid.
If your handheld doesn't trigger anything, swap the 12V battery first — a weak battery transmits but at a power level too low to enroll.
Common GEM wiring faults
- Only one motor runs. Open the junction box — the dead motor's UP, DOWN, or COMMON tap is loose or never bonded into the bus.
- Lift hums and trips the breaker on UP. One motor is wired backward and fighting the others. Power off and confirm every motor uses the same wire color → terminal mapping.
- Receiver clicks but nothing happens. Limit switch jumper was removed and no limit switch is installed yet — wire the limit or re-install the jumper temporarily during commissioning.
- Works on DOWN, dead on UP. Upper limit is open (boat already at the top, switch corroded, or wire broken on the limit run).
Reference only. GEM revisions vary between production years — always confirm against the diagram printed inside the lid of your specific GR1 or GR2 box before you land a wire.