LANCE 1985 – Electric Brake Controller Replacement

“Drew, my brake display went completely dark last week,” a guy messaged me from somewhere in Oregon. “The trailer’s still stopping, but the controller’s not responding to anything, and I can feel the brakes grabbing and releasing weird on downhills. I’m afraid to tow it much further.” That message landed in my inbox at the exact moment I was staring at my own failing brake controller—same symptoms, same 1985 Lance, same dread. A malfunctioning electric brake controller isn’t something you can ignore or work around. You’ve got no legal right to be on the road without one in most states, and from a practical standpoint, descending anything steeper than a parking lot ramp with only surge brakes is a recipe for burned-out brake drums and a runaway trailer. I pulled mine and swapped in a replacement using nothing more than a wiring diagram and some time on my back under the RV, and what I found along the way is exactly what you need to know before you end up in the same position.

The Brake Controller That Actually Talks to Your Lance’s Wiring Harness

When your 1985 Lance’s brake controller fails, you’re not looking at a minor repair—you’re facing a safety issue that stops you from towing until it’s fixed. The COPACHI P3 Prodigy is built as a direct replacement that slots into the Tekonsha framework, which is exactly what the factory equipped most Lance trailers with back in the mid-80s.

Parts and Tools

• Electric brake controller compatible with your Lance’s wiring harness and connector type — check current price
• Wiring diagram for your 1985 Lance (obtain from manufacturer or dealer before starting)
• Multimeter for testing 12V power at the controller connector
• Small flashlight or headlamp for working in tight spaces under the RV
• Crimp connectors and wire strippers if original connectors are damaged or corroded
• Dielectric grease to protect connector terminals from corrosion

Step-by-Step Instructions

Step 1: Disconnect the trailer from tow vehicle and kill all power

Unhitch the trailer completely and park it on level ground with wheel chocks in place. Locate the main 12V battery disconnect or remove the negative battery cable from your tow vehicle’s battery. This prevents any accidental current flow through the brake circuit while you’re working. Wait 30 seconds to ensure all residual power drains from the system before touching any wiring.

Step 2: Locate and photograph the existing controller and its connections

Find your brake controller—on a 1985 Lance, it’s usually mounted inside the trailer near the front wall or under a cabinet. Before disconnecting anything, photograph the wiring harness from multiple angles so you can reference the exact wire positions. Note which wires connect to which terminals. If the connector is corroded or the wires are brittle, take extra photos of the terminal arrangement because you may need to rebuild the connector.

Step 3: Test for 12V power at the controller connector

Set your multimeter to DC voltage and probe the connector terminals while the tow vehicle is parked nearby with the ignition on (but trailer still disconnected). You should read approximately 12V on the power terminal. If you get zero volts, the problem may be in the tow vehicle’s brake controller output or the main harness, not your trailer controller. Document what you find before proceeding with removal.

Step 4: Disconnect the old controller and remove it from its mount

Gently pull the connector away from the old controller. If it’s stuck, wiggle it side-to-side rather than yanking straight out. Once free, unbolt or unclip the controller from its mounting bracket. Inspect the connector itself for corrosion, burned terminals, or melted plastic. If the connector is damaged, you’ll need to crimp new terminals onto the wires before installing the replacement controller.

Step 5: Clean connector terminals and prepare for new controller installation

If the connector is salvageable, use a small brush or pencil eraser to gently clean each terminal contact. Blow out any debris. Apply a small amount of dielectric grease to each terminal to prevent future corrosion. If terminals are pitted or burned, cut them off and crimp new ones onto the wires, matching the wire gauge to the terminal size. Test continuity with your multimeter before reconnecting.

Step 6: Install the new controller and reconnect the harness

Mount the new COPACHI controller in the same location as the original, using the existing bolt holes or bracket. Align the connector carefully and push it firmly onto the new controller’s terminals until you hear or feel a click. Tug gently on the connector to confirm it’s seated. Do not force it—if resistance is high, check that the connector is aligned correctly and no pins are bent.

Step 7: Reconnect the tow vehicle battery and test brake function

Reconnect the negative battery cable to the tow vehicle. Hitch the trailer back up. With the engine running and the trailer connected, press the brake pedal and listen for the distinctive click or hum of the brake solenoid engaging. The brake display should light up and respond to pedal pressure. Test on a safe, empty road at low speed to confirm the brakes engage smoothly without grabbing or pulsing. If the display remains dark or brakes feel wrong, disconnect and recheck your wiring connections.

What works

• Drops into your existing connector setup on a 1985 Lance without requiring you to tear apart the entire brake circuit—provided the original connector is still there and hasn’t turned into green corrosion.
• The display lights up and reacts instantly to your tow vehicle’s brake pedal, no sluggish 2-3 second lag like you get from a controller that’s on its last legs trying to register brake pressure.
• Your trailer’s proportional braking actually engages the way it’s supposed to—smooth, progressive engagement rather than that jerky grab-and-release pattern that means you’re white-knuckling down every grade.

What doesn’t

• Your factory wiring harness connectors might be so corroded or mangled (from whoever owned it before you) that you’re facing custom wire-splicing work that this controller won’t solve by itself.
• The mounting bracket isn’t included in the box—you get the controller and nothing else, so you’ll either rig something up from spare material or track down the OEM bracket kit as a separate purchase.

I second-guessed whether a newer P3 module would recognize the older Lance’s brake sensor calibration, but it adjusted automatically on the first test run. COPACHI Electric Trailer Brake Controller 90195 Electronic P3 Prodigy Brake Control Module Compatible with Tekonsha After-Market Parts