CURT Spectrum Brake Control Installation Manual

Table of Contents

• Controls & Components
• Tools List
• Before You Begin
• Wiring
• Wiring Diagram
• Mounting the LED Display Rotary Knob
• Wiring the Plug Connector to the LED Display Knob
• Uninstalling the Brake Control
• Mounting the Main Module
• Modes & Indicators on the LED Display
• Set Manual Control Output and Brake Light Switches
• Initial Setup
• Test Drive & Adjustment
• Bench Test
• Troubleshooting Guide

Controls & Components

The following components are included:

1. Main module
2. Main module adhesive pad
3. LED display rotary knob
4. Plug connector for LED display
5. Base plate
6. Base plate adhesive pad
7. Well-nut
8. Screw, #6 - 32

Visual Description: An image displays the main module, LED display rotary knob, plug connector, base plate, well-nut, screw, and adhesive pads, along with the tools required for installation.

Tools List

1. Drill
2. Drill bit, 5/16"
3. Phillips screwdriver
4. Pry tool

Before You Begin

Before installation, ensure you have the necessary components:

• Brake control harness, supplied with the tow vehicle (if equipped)
• CURT quick plug harness - custom connector for specific vehicles (refer to CURT catalog)
• CURT #51515 / #51516 - quick plug with pigtails
• CURT #51500 - universal brake control wiring kit

IMPORTANT: Read and follow this installation manual carefully. Failure to do so may result in damage to the brake control unit, loss of trailer brakes, or poor brake performance.

Disconnect the electrical plug between the trailer and tow vehicle before testing a breakaway switch to prevent damage to the brake control unit. Avoid mounting the brake control module near a CB radio or other RF transmitter.

WARNING: The main module and rotary knob must be mounted firmly. Improper mounting can lead to incorrect operation or brake failure.

WARNING: The main module's positive (with 30-amp circuit breaker) and ground wires must be connected directly to the tow vehicle's battery using a minimum of 10-gauge stranded wire. Connecting to existing wiring or an alternate ground may damage vehicle circuits, cause brake control module failure, loss of trailer brakes, or a vehicle fire.

NOTICE: Removal of the factory quick plug may void the warranty.

Wiring

Disconnect the tow vehicle's negative battery terminal before starting. Most trucks and utility vehicles have a factory plug for quick brake control installation; consult your owner's manual for its location and installation. If the vehicle's mating plug is unavailable, a CURT quick plug can be used (see CURT catalog). For vehicles without a factory plug, use the CURT universal brake control wiring kit #51500.

Mount the 30-amp, auto-reset circuit breaker as close to the battery as possible.

IMPORTANT: When passing wires through sheet metal, use an existing grommet. If none exists, install one or use silicone sealant to protect wires from sharp edges.

Connect two 10-gauge wires (one white, one black) from the brake control to the battery area. Connect the black wire to the 'AUX' side of the 30-amp circuit breaker using a ring terminal. Connect the white wire later. Use a 10/12-gauge butt connector to attach the black wire from the circuit breaker's 'AUX' side to the brake control's black wire. Use another 10/12-gauge butt connector to attach the white wire from the battery area to the brake control's white wire.

Run a 10-gauge blue wire from the tow vehicle's trailer plug 'BRAKE' terminal to the brake control. Connect this wire to the brake control's blue wire using a 10/12-gauge butt connector.

Wiring Diagram

Visual Description: A wiring diagram illustrates the connections from a 12-volt battery of a tow vehicle. It shows the negative battery terminal disconnection, a 30A auto-reset circuit breaker connected to the battery (AUX and BATT terminals), a wire tap connected to the stoplight switch (red wire), and a trailer connector. Wires (10 GA) are shown connecting the main module to the battery, circuit breaker, trailer connector (BRAKE BLUE, BATTERY+ BLACK, STOPLIGHT RED, GROUND WHITE), and the LED display rotary knob. It notes the use of butt connectors (not supplied) and a CURT universal pigtail harness or vehicle-specific quick plug.

Mounting the LED Display Rotary Knob

Install the LED display rotary knob before the main module. Two mounting options are available.

Notes: Do not insert terminals into the plug connector yet. Ensure the top of the LED arc faces upward when inserting the knob into the base plate.

Base Plate Installation, Drill Mount Option

1. Determine a suitable mounting location for the LED display knob. Ensure it is secure, easily reachable by the driver, and the area behind it is clear for drilling.
2. Position the base plate and mark the two hole locations.
3. Using a 5/16" drill bit, drill the marked holes. (Note: Figures may show the base plate upside down for clarity due to dash panel removal, which is not required for installation.)
4. Insert the provided well-nut and screw into the outer hole of the base plate to secure it to the dash panel.
5. Feed the LED display knob's cable through the center hole. Insert the knob into the base plate with LEDs upright and press until it clicks.
6. Route the cable behind the dash from the LED display knob to the main module (refer to 'Main Module' section on page 7).

Base Plate Installation, Surface Adhesive Mount Option

1. Determine a suitable mounting location for the LED display knob, ensuring it is secure and easily reachable.
2. Apply the base plate adhesive pad to the base plate and adhere it to the dash in any orientation.
3. Insert the LED display rotary knob into the base plate with LEDs upright and press until it clicks.
4. Route the cable from the LED display knob to the main module (refer to 'Main Module' section on page 7).

Wiring the Plug Connector to the LED Display Knob

Refer to the plug connector image for wire locations. Positions 1 and 8 should remain empty.

Wire Locations:

• 1: No wire
• 2: White
• 3: Green
• 4: Brown
• 5: Blue
• 6: Black
• 7: Red
• 8: No wire

Hold the plug connector with the locking mechanism facing downward. Insert terminals into the connector with the folded metal crimp facing down. Each terminal should click into place and be secure. Once all six terminals are seated, close and latch the locking mechanism.

Uninstalling the Brake Control

To uninstall, the plug connector attached to the LED display knob can be unpinned without cutting the cable. Use a small flat head screwdriver to unlatch the two locking tabs securing the mechanism. Once unlatched, the mechanism opens. Use a pin to gently pry up the plastic tab securing each terminal while gently pulling the wire. Repeat for all six terminals. Once free, the brake control can be removed.

Mounting the Main Module

1. Determine a suitable mounting location for the main module, preferably under the dash, ensuring it is securely mounted to a solid surface and can connect to the LED display rotary knob.
2. Refer to the 'Wiring the Plug Connector to the LED Display Knob' section (page 6) and insert the LED display knob's plug connector into the main module.
3. Consult the 'Set Manual Control Output and Brake Light Switches' section (page 11) before final mounting.
4. Once the LED display knob is connected, secure the main module using the provided adhesive pad and/or zip-ties.
5. Plug the main module into the pigtail harness or vehicle-specific quick plug. Hard wiring is necessary if a harness is unavailable.

Modes & Indicators on the LED Display

The LED display shows the output setting when the control is activated. It is used for setup, monitoring, and troubleshooting. There are four modes of operation and three indicator sequences.

Modes

• Manual (red): Controls manual brake application.
• Brightness (white): Adjusts display brightness.
• Output (green - red): Sets maximum power to trailer brakes.
• Sensitivity (blue - red): Adjusts trailer brake aggressiveness.

Indicators

• Calibration (ramp-up): Indicates self-calibration sequence.
• Overloaded (flashing): Signals an overload or short-circuit condition (flashes red and yellow).
• Disconnected (flashing): Indicates trailer disconnection (flashes blue) or pedal press with no trailer (steady blue).

Manual Control (red progression)

Manual brake control activation is used for gradual speed reduction. Pushing the control applies trailer brakes. The manual control can be set for 100% power or limited to the output control setting via a rear switch. The factory default is 'limited to the output control'. The display shows output during manual activation. Brake light activation with manual control is optional; it can be switched off via a second rear switch. The red wire connection is always required.

• Pressing and holding the button activates manual brake output.
• Manual output functions as time-based and ramps up.
• Red LEDs indicate proportional brake output.
• Adjust gain by rotating the knob clockwise (increase) or counter-clockwise (decrease) while holding the button.
• Releasing the button returns to the previous mode.

Brightness Control (white progression)

• Default control state.
• Rotate knob clockwise to increase brightness.
• Rotate knob counter-clockwise to decrease brightness.

Output Control (green to red progression)

Sets the maximum power available to trailer brakes. Can be adjusted during setup, when trailer load changes, or for different driving conditions. Rotating the knob clockwise increases output; counter-clockwise decreases it. Green is the lowest setting, red is the highest. After 10 seconds of inactivity, the display switches to brightness mode and sleeps. Pressing and holding the button activates manual control.

Sensitivity Control (blue to red progression)

Adjusts trailer brake aggressiveness, independent of manual control. Can be adjusted for driver preference, trailer load, or road conditions. Rotating the knob clockwise increases sensitivity; counter-clockwise decreases it. Blue is the lowest setting, red is the highest. After 10 seconds of inactivity, the display switches to brightness mode and sleeps. Pressing and holding the button activates manual control.

Indicators Explained

• Calibration Indicator (ramp-up): Lights green in a clockwise sequence seven times when the control is self-calibrating (power applied, trailer connected).
• Overload Indicator (red and yellow flashing): Indicates an overload or short-circuit condition. LEDs flash red and yellow until the condition is removed.
• Disconnected Indicator (blue flashing): Indicates trailer disconnection (flashing blue). If brakes are pressed with no trailer connected, the indicator is steady blue as long as the pedal is held.

Set Manual Control Output and Brake Light Switches

Two small switches are located at the front of the module, next to the port. Use a small pointed tool to change their positions.

• Switch #2 (Right): Controls manual control output level. Default 'ON' (down) limits output to the set level. 'OFF' (up) allows 100% output regardless of the output control setting.
• Switch #1 (Left): Controls brake light activation feature. Default 'ON' (down) activates tow vehicle and trailer brake lights when manual control is actuated. 'OFF' (up) disables this feature. The red wire connection is still required for the Spectrum™™ brake control to function.

Initial Setup

1. Once all electrical connections are complete, plug the trailer's electrical connector into the tow vehicle's plug while parked on a level surface. This initiates the mounting position calibration mode, indicated by a green LED ramp-up sequence. To recalibrate, unplug and re-plug the trailer connector.
2. With the trailer connected and engine running, make preliminary adjustments for proper charge voltage. Ensure the vehicle is in park or neutral, the parking brake is applied, the foot is off the brake pedal, and no manual control is actuated.
3. Adjust Output: Press the rotary knob to enter output control mode (green-red LEDs). Rotate the knob clockwise or counter-clockwise to set the desired output control.
4. Adjust Sensitivity: Press the rotary knob to enter sensitivity control mode (blue-red LEDs). Rotate the knob clockwise or counter-clockwise to set the desired sensitivity.

Test Drive & Adjustment

Both output and sensitivity can be adjusted for smooth, firm stops. Perform adjustments only when stopped, with the transmission in park or neutral, parking brake applied, and foot off the brake pedal.

1. Output Adjustment: Drive forward on a dry, level surface at approximately 25 mph. Apply the vehicle's brakes. If trailer braking is insufficient, rotate the LED display knob clockwise. If trailer brakes lock up, rotate counter-clockwise. Repeat until stops are firm, just short of lock-up.
2. Sensitivity Adjustment: Once output is set, drive at approximately 25 mph and press the brake pedal. The vehicle and trailer should stop smoothly. If the stop is slow and more aggressive braking is desired, rotate the LED display knob clockwise. If the stop is too aggressive, rotate counter-clockwise.
3. Make several stops at various speeds, adjusting sensitivity for smooth, firm stops. Slight output control adjustments may also be needed.

Note: For any problems during setup, refer to the 'Troubleshooting Guide' on the last two pages.

Bench Test

Parts Needed:

1. Standard 1156 automotive bulb in a socket
2. Charged 12V battery
3. Alligator clip test leads OR wire and wire nuts
4. CURT #51515 / #51516 quick plug with pigtails OR push pins

Note: If a quick plug pigtail is not available, push pins can connect directly to the Spectrum™™ quick plug housing terminals.

CAUTION: Ensure brake control wires, quick plug wires, push pins, and test leads do not contact each other or any metal surface, as this may damage the brake control.

Brake Control Setup

Connect the main module to the LED display using the wiring connector. Connect the quick plug to the main module for accessible test points. Connect the white ground wire of the main module and the bulb's ground wire to the 12V battery's negative terminal. Leave the red brake input wire and blue output wire unconnected for now. Connect the black battery wire of the main module to the 12V battery's positive terminal. If wired correctly, the Spectrum™™ LED display will flash blue on the edges.

Brake Control Setup - Continued

Ensure the Spectrum™™ is level on the bench surface. Connect the bulb's signal wire to the Spectrum™™'s blue brake output wire. The LED display will ramp-up green, indicating calibration check. This confirms power to the Spectrum™™ and allows testing of manual control and accelerometer.

Manual Control Testing

Set the output to maximum and sensitivity to its most aggressive setting. Activate manual control to full output. The bulb's brightness should correspond to the brake control's output. Release the manual control to deactivate.

Accelerometer Testing

With the brake control level, connect the red brake input wire to the 12V battery's positive terminal. The brake control output will activate, and the bulb may be dimly lit. Slowly tilt the main module to about 45°. The bulb's brightness should increase, corresponding to the output. Slowly return the module to level; the bulb's brightness should decrease.

After testing, disconnect all wiring from the 12V battery's positive terminal, ensuring exposed contacts do not touch. If the Spectrum™™ does not function as described, return it for service or replacement.

IMPORTANT: Read and follow all warnings and cautions shown on the battery.

Visual Description: A diagram shows the bench test wiring. It includes a 12V battery, a standard 1156 automotive bulb in a socket, the CURT #51515/#51516 quick plug, and connections for RED (BRAKE SIGNAL), BLUE (BRAKE OUTPUT), BLACK (BATTERY), and WHITE (GROUND) wires.

Troubleshooting Guide

Warranty & Product Registration

CURT Group offers industry-leading warranties. Register your purchase at warranty.curtgroup.com/surveys to help improve product lines and understand customer needs. CURT Group values customer feedback for product improvements.