Heartland Bighorn 2013 Electrical Wiring Schematic Guide and Troubleshooting
Start by locating the main power distribution panel behind the rear storage compartment on the driver’s side. Disconnect the 12V battery before inspecting connections to avoid short circuits. Use a multimeter set to 200 ohms to test continuity across fuses F12 (interior lighting) and F15 (slide-out motor relay). If readings exceed 0.5 ohms, replace the fuse or trace the wiring harness for breaks near the axle-mounted junction box.
The 7-way trailer plug often corrodes at terminals 3 (left turn/brake) and 4 (right turn/brake). Remove the plug housing and apply dielectric grease to each pin after cleaning with a wire brush. Check the ground wire (pin 1) for secure attachment to the chassis–loose grounds cause intermittent failures in the brake controller and running lights.
For slide-out systems, inspect the motor relay in the under-floor compartment. Use a probe to verify 12V input on relay pin 85 during operation. If voltage is present but the motor doesn’t engage, swap the relay with the spare (identical part number 40-16726-01) stored above the freshwater tank. Replace frayed wires in the harness bundle running along the frame rail–use heat-shrink tubing (1/4″ diameter) for repairs.
HVAC issues frequently stem from the thermostat wiring. At the control board (behind the wall panel in the main living area), confirm color-coded connections match the factory-supplied reference chart: red (R) to power, green (G) to fan, yellow (Y) to compressor, and white (W) to heat. Miswired connections overheat the system–reposition terminals using pliers if slots appear melted.
For water heater diagnostics, bypass the electronic ignition temporarily by jumpering the thermal cut-off switch (located under the burner assembly) with an 18-gauge wire. If the pilot lights, replace the switch (part #10-1488). Verify the propane solenoid receives 12V at terminal 5 when the gas valve is activated–absent voltage indicates a faulty control module near the refrigerator.
Key Electrical Layout for RV Systems in Fifth-Wheel Models
Begin troubleshooting by locating the main distribution panel–typically mounted near the entry door or inside a utility compartment. Label each breaker with its corresponding circuit: slide-out motors, refrigerator, water heater, and lighting zones require distinct paths. Verify voltage at the battery disconnect switch first; if readings drop below 11.8V under load, inspect connections for corrosion or loose terminals within the first 10 minutes of testing. Replace any crimped wires showing green oxidation or frayed insulation.
Trace the 12V power feed from the coach batteries to the converter, noting color codes: red (positive), black (negative), and blue (grounded neutral). Disconnect shore power before probing the reverse polarity relay; a multimeter should read zero ohms between the neutral and ground buses in the panel. If resistance exceeds 0.5 ohms, replace the relay immediately to prevent inverter damage during AC operation.
Common Failure Points and Fixes
- Slide-out motor stalling: Check the limit switch wires (usually yellow/black striped) for pinched sections near the wall joints. Bypass the switch temporarily to isolate the issue.
- Refrigerator not cooling on LP: Inspect the thermistor at the rear cooling unit; corrosion here mimics gas valve failures. Clean contacts with 1000-grit sandpaper if resistance reads above 2.2 kΩ.
- Dimmer lights flickering: Swap the PWM controller module located behind the switch panel. Test with a spare halogen bulb–LED fixtures often overload weak modules.
For 120V AC circuits, map the transfer switch wiring: black wires terminate on the internal breaker, while white markers denote shore power inputs. Use a non-contact voltage tester to confirm no residual current remains after flipping the main breaker. Replace any outlet showing scorch marks; arc faults here propagate rapidly through adjacent circuits.
- Label every wire at both termination points–use heat-shrink tubing for durability.
- Test all GFCI outlets monthly; press the “Test” button and verify the yellow LED on the converter panel illuminates within 3 seconds.
- Document fuse ratings: 25A for stabilizer jacks, 15A for LP detector, 5A for awning motors.
- Upgrade the battery charger if float voltage exceeds 14.6V–lithium batteries require 13.8V precise settings.
Locating the Main Power Distribution Panel and Fuse Box Layout
Begin by examining the forward storage compartment beneath the living area’s entry steps–this is the primary housing for the electrical hub in most fifth-wheel trailers. The panel is typically recessed behind a snap-fit or hinged plastic cover, labeled with a small red or black icon resembling a lightning bolt or breaker symbol. Verify its exact position by tracing the heavy-gauge cables from the battery disconnect switch, which should lead directly to the panel’s input terminals.
The layout inside features two distinct sections: the circuit breakers on the left and the fuse block on the right. Circuit breakers are grouped in rows of three or four, each corresponding to a specific appliance or subsystem–common labels include “Water Heater,” “Furnace,” “Refrigerator,” and “Converter.” The fuse block, separated by a thin divider, contains blade-type fuses (typically ATO/ATC, rated between 5A and 30A) for smaller loads like interior lighting, slide-out motors, and entertainment systems. Use a multimeter set to continuity mode to confirm each fuse’s integrity before removal.
Key Terminal Identification
At the top of the panel, identify the main bus bar, a thick copper strip connected to the trailer’s 12V battery bank via a 100A–150A inline fuse. Below it, look for the distribution bus, a secondary strip feeding lower-amperage circuits. Each breaker’s screw terminal should be torqued to 12–15 in-lbs to prevent loosening during travel; check tightness with a calibrated torque screwdriver. Note the color-coding: red wires denote positive feeds, black or white with black tracer mark grounds, and yellow or blue indicate switched circuits (e.g., stabilizer jacks or awning controls).
For troubleshooting, label each connection using a P-touch or similar label maker before disconnecting any wires. Document the amperage rating adjacent to each breaker or fuse–most 12V devices draw 10A–20A, while larger loads (microwave, air conditioner, or inverter) may require dedicated 30A–50A breakers. If replacing a blown fuse, match the amp rating exactly; substituting a higher-rated fuse risks overheating wires and melting insulation, particularly in circuits powering slide mechanisms or hydraulic leveling systems.
In trailers equipped with a solar charge controller or inverter/charger, locate a secondary sub-panel adjacent to or beneath the main hub. This panel often contains smaller breakers or fuses (5A–15A) for solar input, lithium battery management, and inverter output. Verify the system’s ground connection–it should terminate at the chassis via an 8–10 AWG bare copper wire, bonded with a stainless-steel bolt and serrated washer for corrosion resistance. Avoid daisy-chaining ground wires; each major component (fridge, HVAC, converter) should have a dedicated path to the chassis ground point.
Identifying Circuit Linkages for Expandable Room Assemblies
Begin by locating the main power distribution panel behind the control switch for the retractable section. Look for a quad-color harness bundle–typically black, red, blue, and yellow–terminating in a 6-pin circular connector. This connector mates directly to the motor actuator. Confirm continuity between the red lead (constant 12V) and the chassis ground using a multimeter set to DC voltage; readings should stabilize at 12.6–13.2V.
Trace the blue conductor from the harness to the reversing relay. The relay coil draws 800mA when energized, triggering the contactor to swap polarity for deployment or retraction. Test relay functionality by applying 12V across the coil terminals (pins 85 and 86) while monitoring continuity between pins 30 and 87a; an audible click should coincide with circuit closure. If absent, replace the relay–generic Bosch-style part #5173 fits most models.
Isolate the limit switch circuit by disconnecting the yellow wire from the actuator. Use a continuity tester to verify the switch’s operation: it should open at full extension (24.5 inches) and close upon 1-inch retraction. Adjust the cam plate position if activation thresholds are misaligned–loosening the two M6 set screws allows ±3mm fine-tuning without disassembling the track.
Check the thermal overload protector embedded in the actuator housing. The device trips at 180°C and resets automatically after cooling for 15 minutes. To bypass temporarily for testing, splice in a 20A fuse holder with a 15A fuse–this protects the system if the protector fails closed but does not substitute for replacement (part #EX-3428).
| Connector Pin | Wire Color | Function | Expected Voltage |
|---|---|---|---|
| 1 | Black | Chassis ground | 0V |
| 2 | Red | Battery positive | 12.6–13.2V |
| 3 | Blue | Relay trigger | 0V (idle), 12V (active) |
| 4 | Yellow | Limit switch signal | 12V (closed), 0V (open) |
| 5 | Green (optional) | LED indicator | 3.3V (illuminated) |
| 6 | White | Motor negative | Pulsed 0–12V during operation |
Inspect the ground return path for corrosion at the frame attachment point. Scrape paint from the mounting surface and apply dielectric grease to the M10 bolt after torquing to 45 ft-lbs. A high-resistance ground (above 0.5Ω) will cause erratic actuator behavior, often diagnosed as “phantom jamming” during mid-stroke pauses.
For systems with synchronized dual actuators, ensure both motor assemblies share identical gearbox ratios (standard: 24:1). Mismatched ratios cause uneven extension, detected by measuring transit time: divergence exceeding 0.8 seconds between sides indicates replacement of the slower unit. Use an oscilloscope to verify PWM signals match within 5% duty cycle tolerance.
Secure all bundles with Panduit ties spaced 6 inches apart, avoiding sharp edges or moving components. Route harnesses parallel to the slide mechanism’s linear motion axis, allowing 1-inch slack at full extension. Re-terminate any frayed conductors using silver-soldered butt splices, then seal with adhesive-lined heat shrink tubing rated for -40°C to +125°C.