Where is the engine diagnostic port (OBD II/SAE plug) located on my Tiffin motorhome?
The engine diagnostic port (OBD-II or SAE J1939 plug) on your Tiffin motorhome depends on the chassis manufacturer—but here’s how to find it based on the most common setups:
🚌 For Tiffin Diesel Pushers (Allegro Bus, Phaeton, Zephyr)
Chassis: Freightliner Custom Chassis (FCC)
- Diagnostic Port Location:
- Directly under the dash near the steering column, driver’s left side.
- Sometimes hidden behind a removable cover or knee panel.
- You’re looking for a 9-pin round connector (J1939) — not a standard car-style OBD-II.
Freightliner uses the J1939 protocol—not OBD-II.
- You'll need a compatible scan tool like the BlueFire or SilverLeaf engine monitor,
- or a shop-grade J1939 scanner.
🚐 For Tiffin Gas Coaches (Open Road Allegro, RED)
Chassis: Ford F-53 (for gas engines)
- Diagnostic Port Location:
- Standard OBD-II port located under the dashboard near the driver's side footwell, left of the steering column.
You can use any standard OBD-II code reader or scan tool on gas models.
🔎 Tips for Finding It:
- Look just above your left knee when seated.
- Use a flashlight—sometimes the port is tucked behind a plastic shroud or tucked tight to the dash frame.
- If you don’t see a port, feel around behind the dash edge or check inside a fuse panel door.