Product Details
- Brand: Draw-Tite
- Model: 118747 85343 20506 7012A
- Includes: T-One T-Connector Custom Harness, Wiring Adapter, Trailer Brake Controller Installation Kit, Circuit Breaker
Compatibility Chart
Description
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Trailer Hitch 7 Way RV Wiring Kit For 16-22 Mercedes-Benz GLC Except PO3 Premium Package Plug Prong Pin Brake Control Ready Install Notes
Installation Instructions for T-One® T-Connector for Mercedes GLC300
Part Numbers:
- 118747
Tools Required:
- 10mm Socket & Ratchet or Wrench
- Drill (3/32” Drill Bit)
- Wire Crimpers
- Wire Cutters
- Phillips Head Screwdriver
Step-by-Step Instructions:
-
Prepare the Vehicle:
- Open the rear hatch and temporarily remove the rear threshold plate.
-
Access the Taillight Wiring Harness:
- On both the driver and passenger sides, remove the access panels.
- Locate the taillight wiring harness with connection points matching the T-One® Connector ends. Separate the connectors carefully to avoid damaging the locking tabs. Clean all connector surfaces.
-
Connect the Passenger-Side T-Connector:
- Route the harness with the green wire through the opening in the side panel near the threshold and up behind the taillight pocket.
- Insert the T-One® Connector end with the green wire between the vehicle wiring connectors. Lock into place, ensuring the connectors are fully inserted and secure.
-
Connect the Driver-Side T-Connector:
- Locate the access hole on the driver’s side between the spare tire and rear threshold.
- Route the T-One® Connector end with the yellow wire up through the hole to the access panel.
- Insert the T-One® Connector end with the yellow wire between the vehicle wiring connectors and lock into place.
-
Mount the Black Box Module:
- On the passenger side, mount the T-One® Connector black box using the provided double-sided tape.
- Secure the remaining T-One® Connector harness with the supplied cable ties to prevent damage or rattling. Avoid areas that may cut or pinch the wire.
-
Ground the White Wire:
- Locate a suitable grounding point near the connector, such as an existing ground stud, or drill a 3/32” hole. Secure the white wire using the provided eyelet and screw.
- Caution: Verify what is behind any surface before drilling to avoid damage or injury. Do not drill into exposed surfaces.
-
Connect the Power Wire:
- On the passenger side, locate the black 12-gauge power wire from the T-One® Connector black box.
- Attach the provided black 12-gauge wire and route it along the exterior frame or follow existing wiring to the engine compartment. Avoid areas that may pinch, cut, or break the wire.
Warning: If routing through a grommet and along the exterior, avoid hot pipes, heat shields, fuel tanks, or other hazardous points.
-
Connect to the Vehicle Battery:
- Disconnect the vehicle’s Negative (-) battery cable.
- Remove the fuse from the yellow fuse holder.
- Attach the ring terminal to the Positive (+) battery cable and connect the other end of the fuse holder to the black 12-gauge wire using the yellow butt connector.
Warning: Follow all warnings and cautions related to the tow vehicle’s battery. Ensure all connections are complete for proper functionality.
-
Secure the Wiring Harness:
- Use the provided cable ties to secure the remaining T-One® Connector harness, avoiding areas that may pinch, cut, or melt the wire.
-
Reassemble the Vehicle:
- Reinstall the plastic trim panels, threshold, storage covers, floor covering, and any other removed items.
-
Store the 4-Flat Connector:
- Store the 4-flat connector in the rear cargo area when not in use.
-
Test the Installation:
- Insert the 15-amp fuse into the fuse holder.
- Test the installation using a test light or trailer. Reset the vehicle’s electrical system by temporarily removing the key from the ignition.
Safety Notes:
- Overloading circuits can cause fires. Do not exceed stated product ratings or vehicle manufacturer specifications.
- Always wear safety glasses and follow safety precautions during installation.
Manufacturer Notes:
- Refer to the vehicle owner’s manual and the instruction sheet for additional details.
- Store these instructions for future reference.
Installation Instructions for T-One® T-Connector for Mercedes GLC300
Part Numbers:
- 118747
Tools Required:
- 10mm Socket & Ratchet or Wrench
- Drill (3/32” Drill Bit)
- Wire Crimpers
- Wire Cutters
- Phillips Head Screwdriver
Step-by-Step Instructions:
-
Prepare the Vehicle:
- Open the rear hatch and temporarily remove the rear threshold plate.
-
Access the Taillight Wiring Harness:
- On both the driver and passenger sides, remove the access panels.
- Locate the taillight wiring harness with connection points matching the T-One® Connector ends. Separate the connectors carefully to avoid damaging the locking tabs. Clean all connector surfaces.
-
Connect the Passenger-Side T-Connector:
- Route the harness with the green wire through the opening in the side panel near the threshold and up behind the taillight pocket.
- Insert the T-One® Connector end with the green wire between the vehicle wiring connectors. Lock into place, ensuring the connectors are fully inserted and secure.
-
Connect the Driver-Side T-Connector:
- Locate the access hole on the driver’s side between the spare tire and rear threshold.
- Route the T-One® Connector end with the yellow wire up through the hole to the access panel.
- Insert the T-One® Connector end with the yellow wire between the vehicle wiring connectors and lock into place.
-
Mount the Black Box Module:
- On the passenger side, mount the T-One® Connector black box using the provided double-sided tape.
- Secure the remaining T-One® Connector harness with the supplied cable ties to prevent damage or rattling. Avoid areas that may cut or pinch the wire.
-
Ground the White Wire:
- Locate a suitable grounding point near the connector, such as an existing ground stud, or drill a 3/32” hole. Secure the white wire using the provided eyelet and screw.
- Caution: Verify what is behind any surface before drilling to avoid damage or injury. Do not drill into exposed surfaces.
-
Connect the Power Wire:
- On the passenger side, locate the black 12-gauge power wire from the T-One® Connector black box.
- Attach the provided black 12-gauge wire and route it along the exterior frame or follow existing wiring to the engine compartment. Avoid areas that may pinch, cut, or break the wire.
Warning: If routing through a grommet and along the exterior, avoid hot pipes, heat shields, fuel tanks, or other hazardous points.
-
Connect to the Vehicle Battery:
- Disconnect the vehicle’s Negative (-) battery cable.
- Remove the fuse from the yellow fuse holder.
- Attach the ring terminal to the Positive (+) battery cable and connect the other end of the fuse holder to the black 12-gauge wire using the yellow butt connector.
Warning: Follow all warnings and cautions related to the tow vehicle’s battery. Ensure all connections are complete for proper functionality.
-
Secure the Wiring Harness:
- Use the provided cable ties to secure the remaining T-One® Connector harness, avoiding areas that may pinch, cut, or melt the wire.
-
Reassemble the Vehicle:
- Reinstall the plastic trim panels, threshold, storage covers, floor covering, and any other removed items.
-
Store the 4-Flat Connector:
- Store the 4-flat connector in the rear cargo area when not in use.
-
Test the Installation:
- Insert the 15-amp fuse into the fuse holder.
- Test the installation using a test light or trailer. Reset the vehicle’s electrical system by temporarily removing the key from the ignition.
Safety Notes:
- Overloading circuits can cause fires. Do not exceed stated product ratings or vehicle manufacturer specifications.
- Always wear safety glasses and follow safety precautions during installation.
Manufacturer Notes:
- For complete installation instructions, including diagrams and detailed information from the manufacturer, please download the full installation PDF.
- Refer to the vehicle owner’s manual for additional details.
- Store these instructions for future reference.
Technical Support:
For technical support and assistance, our team of experts is available to help. You can reach our tech support by visiting www.trailerjacks.com or calling 877-869-6690.
Warranty:
For complete warranty instructions, please download the full installation PDF.
Installation Instructions for 4-Way to 7-Way Adapter and Brake Control Wiring
Tools Required:
- Phillips Head Screwdriver
- Drill with 3/32" Drill Bit
- 10mm Socket & Ratchet or Wrench
- Wire Crimpers
- Wire Cutters
- Test Light or Multimeter
- Cable Ties
Part 1: Install the 4-Way to 7-Way Adapter
Step-by-Step Instructions:
-
Mount the Adapter:
- Choose a suitable mounting point on the vehicle, typically near the hitch.
- Use the provided bracket and screws to secure the adapter.
-
Connect the 4-Flat Plug:
- Plug the 4-flat connector on the adapter into the existing 4-flat plug on the vehicle.
- This connection enables tail lights, left turn, and right turn signals.
-
Ground the Adapter:
- Locate a clean, solid grounding point near the adapter.
- Drill a 3/32" hole if necessary and secure the white ground wire from the adapter using the provided screw and eyelet.
-
Leave Additional Wires Disconnected:
- The following wires will remain disconnected until Part 2:
- Black Wire: Power from the battery.
- Blue Wire: Brake control output.
- Yellow Wire: Reverse light (optional; leave disconnected unless needed).
- The following wires will remain disconnected until Part 2:
-
Test Initial Connection:
- Use a test light or trailer to verify functionality of the 4-way connections (tail lights, turn signals).
Part 2: Install Brake Control Wiring
Step-by-Step Instructions:
-
Mount Circuit Breakers:
- Install two 30A circuit breakers on the firewall or another suitable location near the battery.
- Use self-tapping screws to mount them securely.
-
Route Power Wires:
- Connect the black 12-gauge wire from the 7-way adapter to the auxiliary side of one circuit breaker (this powers the 7-way socket).
- Run a heavy-gauge wire from the battery's positive terminal to the battery side of this circuit breaker, using a ring terminal.
- Run another heavy-gauge wire from the battery's positive terminal to the auxiliary side of the second circuit breaker (for the brake controller).
-
Install the Brake Controller:
- Mount the brake controller under the dash on a firm surface.
- Use the following connections:
- Red Wire: Connect to the cold side of the brake switch (active only when the brake pedal is pressed).
- Blue Wire: Connect to the blue wire on the 7-way adapter for trailer brakes.
- White Wire: Connect to a solid ground point on the vehicle body.
- Black Wire: Connect to the auxiliary side of the second 30A circuit breaker (provides power to the brake controller).
-
Optional: Connect Reverse Light Circuit:
- If the trailer has a reverse light circuit, connect the yellow wire from the 7-way adapter to the vehicle’s reverse light circuit.
-
Reconnect the Battery:
- Reattach the negative battery cable and ensure all connections are secure.
- Insert the fuses into both circuit breakers.
-
Secure All Wires:
- Use cable ties to secure all loose wires and prevent damage or rattling.
-
Test the System:
- Verify functionality of all circuits (running lights, turn signals, brake lights, and brake controller output).
- If applicable, test the reverse light circuit.
Notes:
- Most installations will only require connecting the black and blue wires from the 7-way adapter.
- Leave the yellow wire disconnected unless the trailer has a reverse light or surge brake lockout circuit.
- Always adhere to safety guidelines and verify all connections before use.
Warning: Incorrect wiring can cause damage to the vehicle or trailer. Test all connections carefully before use.
Installation Instructions for 4-Way to 7-Way Adapter and Brake Control Wiring
Tools Required:
- Phillips Head Screwdriver
- Drill with 3/32" Drill Bit
- 10mm Socket & Ratchet or Wrench
- Wire Crimpers
- Wire Cutters
- Test Light or Multimeter
- Cable Ties
Part 1: Install the 4-Way to 7-Way Adapter
Step-by-Step Instructions:
-
Mount the Adapter:
- Choose a suitable mounting point on the vehicle, typically near the hitch.
- Use the provided bracket and screws to secure the adapter.
-
Connect the 4-Flat Plug:
- Plug the 4-flat connector on the adapter into the existing 4-flat plug on the vehicle.
- This connection enables tail lights, left turn, and right turn signals.
-
Ground the Adapter:
- Locate a clean, solid grounding point near the adapter.
- Drill a 3/32" hole if necessary and secure the white ground wire from the adapter using the provided screw and eyelet.
-
Leave Additional Wires Disconnected:
- The following wires will remain disconnected until Part 2:
- Black Wire: Power from the battery.
- Blue Wire: Brake control output.
- Yellow Wire: Reverse light (optional; leave disconnected unless needed).
- The following wires will remain disconnected until Part 2:
-
Test Initial Connection:
- Use a test light or trailer to verify functionality of the 4-way connections (tail lights, turn signals).
Part 2: Install Brake Control Wiring
Step-by-Step Instructions:
-
Mount Circuit Breakers:
- Install two 30A circuit breakers on the firewall or another suitable location near the battery.
- Use self-tapping screws to mount them securely.
-
Route Power Wires:
- Connect the black 12-gauge wire from the 7-way adapter to the auxiliary side of one circuit breaker (this powers the 7-way socket).
- Run a heavy-gauge wire from the battery's positive terminal to the battery side of this circuit breaker, using a ring terminal.
- Run another heavy-gauge wire from the battery's positive terminal to the auxiliary side of the second circuit breaker (for the brake controller).
-
Install the Brake Controller:
- Mount the brake controller under the dash on a firm surface.
- Use the following connections:
- Red Wire: Connect to the cold side of the brake switch (active only when the brake pedal is pressed).
- Blue Wire: Connect to the blue wire on the 7-way adapter for trailer brakes.
- White Wire: Connect to a solid ground point on the vehicle body.
- Black Wire: Connect to the auxiliary side of the second 30A circuit breaker (provides power to the brake controller).
-
Optional: Connect Reverse Light Circuit:
- If the trailer has a reverse light circuit, connect the yellow wire from the 7-way adapter to the vehicle’s reverse light circuit.
-
Reconnect the Battery:
- Reattach the negative battery cable and ensure all connections are secure.
- Insert the fuses into both circuit breakers.
-
Secure All Wires:
- Use cable ties to secure all loose wires and prevent damage or rattling.
-
Test the System:
- Verify functionality of all circuits (running lights, turn signals, brake lights, and brake controller output).
- If applicable, test the reverse light circuit.
Notes:
- Most installations will only require connecting the black and blue wires from the 7-way adapter.
- Leave the yellow wire disconnected unless the trailer has a reverse light or surge brake lockout circuit.
- Always adhere to safety guidelines and verify all connections before use.
Warning: Incorrect wiring can cause damage to the vehicle or trailer. Test all connections carefully before use.
Attention:
This is a summary of the installation procedure. For complete installation instructions, including diagrams and detailed information from the manufacturer, please download the full installation PDF.
Warranty Information:
For complete warranty instructions, please download the full installation PDF.
Technical Support:
For technical support and assistance, our team of experts is available to help. You can reach our tech support by visiting www.trailerjacks.com or calling 877-869-6690.