Keystone Montana – Furnace Igniter & Control Board Replacement

Keystone Montana furnaces built between 2010 and 2018 use a Suburban or Atwood heating unit with a control board that sits right where vibration and temperature swings can wear it out faster than you’d expect. I’ve seen them fail at elevation, in cold snaps, and sometimes just from sitting unused for a season. The igniter may look fine, the thermostat may call for heat, but nothing happens—and when you’re parked in the Rockies or high desert without hookups, a dead furnace isn’t a minor repair, it’s a genuine safety problem. This guide covers the control board replacement and igniter swap I’ve completed on my own Montana, field-tested under real conditions, with step-by-step diagnostics to confirm which part actually failed before you spend money replacing both.

How the Furnace Control Board Became My First Suspect—and Why

Your Montana’s furnace relies on that control board to orchestrate the entire sequence: spark the igniter, verify flame with the sail switch, ramp up the blower fan. Lose the board and the furnace becomes a useless hunk of metal, no matter how much propane you’re feeding it.

Where this repair wins

• Drops straight into most Suburban and Atwood furnace cavities without fabrication or adapter hunting, letting you finish the job in your driveway and get back to staying warm within the hour
• Runs through the complete ignition and fan-cycle sequence, which actually lets you pin down whether the board itself was the failure point or if the problem sits upstream in the thermostat wiring or power supply
• Runs considerably cheaper than hauling your rig to a shop or buying a whole new furnace assembly, which makes this your logical first move before considering anything more drastic

Where it falls short

• Swapping the board doesn’t answer what killed the original—moisture in the cabinet, an electrical surge, simple age—so you might be treating the symptom and leaving the actual culprit in place
• Demands careful connector disconnection on the old board and pixel-perfect wire seating on the new one; a single loose crimp or reversed wire harness and you’re troubleshooting in subfreezing temperatures instead of sleeping warm

I’ll admit I stared at that old board for twenty minutes before pulling the trigger on the replacement, convinced I was missing something obvious—but sometimes the simplest explanation is the right one. If you’re seeing no spark, no blower cycle, or random shutdowns, grab a furnace circuit board / control board and test it first.

Parts and Tools

• Replacement furnace control board / ignition circuit board matched to your Suburban or Atwood furnace model (check the nameplate on your furnace cabinet) — check current price
• Replacement furnace igniter (hot surface igniter) rated for your specific furnace—confirm the part number before ordering
• Wire strippers and small needle-nose pliers for disconnecting and reconnecting igniter and board terminals
• Multimeter set to measure DC voltage and resistance (ohms)
• Flashlight or headlamp for visibility inside the furnace cabinet
• Small Phillips and flathead screwdrivers for terminal screws and mounting brackets
• Camera or phone to photograph wire positions and terminal connections before disconnection

Step-by-Step Instructions

Step 1: Kill power to the furnace at the breaker and verify propane isolation

Locate your RV’s main 12V breaker panel and switch off the furnace circuit. If your Montana has a propane isolation valve near the furnace, close it. Wait five minutes to allow any residual charge to bleed from the control board. Check that the thermostat no longer responds when you adjust it—this confirms the circuit is dead. Do not proceed until you’re certain power is off; a live board can deliver a shock and ignite propane vapor.

Step 2: Photograph the existing wiring and remove the furnace access panel

Take clear photos of every wire connected to the old control board and igniter, including wire colors and terminal positions. Most Montana furnaces have a removable front panel or side cover held by three to five screws. Remove these fasteners and set them aside in a labeled container. Slide or lift the panel away carefully—don’t force it, as internal baffles may be tight. You now have full view of the board, igniter, and sail switch.

Step 3: Test the igniter resistance and the old board for voltage response

Set your multimeter to the ohms (resistance) setting. Disconnect the igniter wire from the board terminal and probe the igniter leads directly. A working igniter typically reads 40–100 ohms; an open circuit (infinite resistance) or a short (near zero) means it’s failed. Reconnect the igniter. Now restore power briefly and measure DC voltage at the board’s igniter output terminal while the thermostat calls for heat. No voltage spike means the board is dead; voltage present but no igniter glow means the igniter failed. Kill power again before proceeding.

Step 4: Disconnect and remove the failed control board

Loosen the terminal screws on the old board one at a time, noting wire colors as you go (your photos are your backup). Gently pull each wire free. Unscrew the board’s mounting bracket—usually two or three fasteners—and slide the board out of its slot. Set it aside. Do not discard it yet; if the new board doesn’t solve the problem, you may need to troubleshoot the thermostat circuit or power supply, and the old board can help you trace those connections.

Step 5: Install the new control board and reconnect all wires

Slide the new board into the same mounting slot, ensuring it sits flush and level. Secure it with the original mounting screws—snug them firmly but do not over-tighten, as the board is plastic and cracks easily. Reconnect each wire to its corresponding terminal, matching your photos exactly. Tighten each terminal screw until the wire is held firmly but not stripped. Double-check that no wires are pinched between the board and the cabinet wall.

Step 6: Replace the igniter if it tested open or shorted

If your multimeter confirmed the igniter failed, disconnect its wire from the new board terminal. Locate the igniter’s mounting bracket—usually a single screw or clip inside the furnace combustion chamber. Remove the fastener and slide the old igniter out. Insert the new igniter into the same position, ensuring the tip sits at the correct distance from the burner orifice (typically 1/8 inch; check your furnace manual). Secure the mounting bracket and reconnect the wire to the board terminal, matching the original polarity.

Step 7: Reinstall the access panel and restore power

Slide the furnace access panel back into place and secure all fasteners. Ensure no wires are pinched or routed across sharp edges. Return to your breaker panel and switch the furnace circuit back on. Open the propane isolation valve if you closed it. Wait 30 seconds for the board to initialize.

Step 8: Test the furnace ignition and blower cycle

Set your thermostat to heat mode and raise the setpoint above the current cabin temperature. Listen for the igniter to spark (a faint clicking or crackling sound) and watch for a flame at the burner opening if you can see it through the access hole. The blower fan should start within 10–15 seconds of ignition. Let the furnace run for two minutes, then lower the thermostat below room temperature to stop the cycle. Repeat the test twice more to confirm consistent ignition and shutdown. If the igniter sparks but no flame appears, check propane flow and the sail switch; if nothing happens, the board or thermostat circuit may still be faulty.