Complete repair guide for the Tiffin Wayfarer – Furnace Igniter & Control Board Replacement. Follow these steps to diagnose and fix the issue yourself.
Parts & Tools You’ll Need
- Suburban RP-35Q 35,000 BTU/h RV Replacement Core for Suburban Furnace Series SF-35, SF-35Q, SF-42, SF-42Q, and SF-Q (2609A) — Suburban/Atwood RV furnace (replacement unit)
- Fit For Suburban RV Furnace Parts 232286,Single Probe Gas Furnace Igniters Electrode with Wire Assembly, Camper Furnace For Suburban 232286 Above 934701426 SF-20, SF-25, SF-30, SF-35 (SF Series) — Furnace igniter electrode
- DTAIR 33082 Sail Switch Replacement for Select Dometic Atwood RV Furnace(Pack of 2) — Furnace sail switch
- 520814 Rv Water Heater Module Board Ignition Control Circuit Board Compatible with Suburban Furnace SW4D, SW6D, SW6DE, SW12D, SW6DEM RV Water Heaters,Replace 520814 520820 520871 33550L (With lid) — Furnace circuit board / control board
- DTAIR 33082 Sail Switch Replacement for Select Dometic Atwood RV Furnace(Pack of 2) — Furnace high-limit switch
- Suburban 232684 RV Furnace 12v SF-Series DC Blower Motor, SF-35, SF-35F, SVF-35, SF-42, SF-42F OEM Caliber — Furnace blower motor (12V DC)
- RV Carbon Monoxide & Propane Gas Alarm, Briidea Dual LP/CO Detector with Separate LED Indicator Light, 100dB Loud Alarm, 12 VDC, Black — Propane/CO combo detector alarm
- FKM Pro Digital Multimeter Tester TRMS 6000 Counts,Smart Rechargeable Voltmeter 5″Color LCD,Auto-Ranging Automotive Multimeters,for AC/DC Current/Voltage,NCV,Ohm,Capacitance,Resistance,Continuity,Temp — Digital multimeter
Step 1: Diagnose Furnace Ignition Problems
Start by listening for the blower motor to engage when you turn on the furnace—if you hear the fan but smell propane without ignition, your igniter electrode or control board is likely the culprit. Use your digital multimeter set to DC voltage to check for 12V at the igniter electrode connector; if you’re getting no voltage or a reading below 10V, the circuit board has failed. Document whether your furnace attempts ignition (clicking sound) or remains completely silent, as this distinction helps isolate whether the problem is the electrode, board, or sail switch.
Step 2: Safely Disconnect Power and Propane
Turn off the main 12V DC battery disconnect switch at your RV’s electrical panel and shut off the propane supply at the tank valve by turning it clockwise until snug. Wait 5 minutes for any residual propane in the line to dissipate, then confirm no hissing sound comes from the furnace burner area. This dual shutdown prevents electrical shock and propane gas exposure while you work on the furnace components.
Step 3: Remove and Inspect Igniter Electrode
Locate the furnace igniter electrode on your Suburban/Atwood unit—it’s a small ceramic-tipped rod positioned near the burner assembly, typically held by a single screw or bracket. Unscrew and gently pull the electrode straight out, then examine the ceramic tip for cracks, discoloration, or heavy carbon buildup; a healthy igniter has a white or light gray tip with no visible damage. If the tip is blackened, cracked, or worn to less than 2mm, replace it with a new furnace igniter electrode, ensuring the ceramic portion doesn’t touch any metal surfaces during reinstallation.
Step 4: Test and Replace Furnace Control Board
With power disconnected, locate your furnace’s circuit board mounted inside the housing near the blower motor area—it’s typically a small rectangular PCB with 12V and ground connections. Using your digital multimeter, check the board’s power input terminals for any visible corrosion or loose wire crimps; corroded boards must be replaced. Install the new furnace circuit board by matching the wire terminals to your old board’s configuration (take a photo first), ensuring all connections are pushed firmly until you hear a click, then reapply 12V power to verify the control board powers up without tripping any safety switches.
Step 5: Verify Sail Switch and Safety Operation
Inspect the furnace sail switch—a thin metal flapper inside the furnace ductwork that confirms airflow before ignition—by checking that it moves freely without sticking or hanging. If the sail switch appears warped, corroded, or immobile, replace it to prevent the furnace from locking out due to airflow detection failure. Manually move the flapper to confirm the switch clicks audibly when actuated; if silent, replace the furnace sail switch before reassembling your heating system.
Step 6: Reassemble and Reconnect All Components
Reinstall the furnace igniter electrode by screwing it back into its bracket and ensuring the ceramic tip sits 3-5mm away from the burner, with no metal-to-ceramic contact. Reconnect all wire harnesses to your new furnace control board using the photo you took earlier, double-checking that 12V red wires go to positive and black ground wires are secure. Close any access panels or furnace shrouds, then restore propane flow at the tank by turning the valve counterclockwise until hand-tight.
Step 7: Test System and Confirm Safe Operation
Turn on the main 12V battery disconnect and switch the furnace to heating mode, listening for the blower to engage within 10 seconds and the igniter electrode to click (you’ll hear a rapid ticking sound for 3-5 seconds). Once ignition occurs, the flame should light and the furnace should maintain steady heat; if clicking continues without ignition after 15 seconds, the furnace will lock out to prevent propane buildup. Allow the furnace to run for 5 minutes, then check that your Propane/CO combo detector alarm shows no alerts and the ductwork exhaust is odorless, confirming the control board, igniter, and sail switch are functioning correctly.