2022 Freightliner Cascadia — Bulb Sizes (Headlight, Tail, Fog)

Quick reference

Notes:

• The 2022 Cascadia (New Cascadia, 2018+) was offered with both halogen and factory LED headlamp assemblies. LED headlamps and many LED marker/tail lamps are sealed, non‑serviceable modules—replace the complete lamp if inoperative.
• Incandescent tail/marker/license assemblies were still used on some fleet specs; those typically accept the 1157/1156/194 bulb families listed above. Always confirm by checking the part number molded into the lamp housing or by removing the bulb to read its code.

LED vs halogen upgrade considerations

• CANBUS/load monitoring: The Cascadia’s SAM (Signal Acquisition Module) monitors exterior bulbs. Drop‑in LED replacements for 1157/1156/3157/194 can trigger bulb‑out warnings or hyper‑flash unless you use CANBUS‑compatible LEDs or add load resistors (typically 6–8Ω, 50W per circuit). Mount resistors to metal away from wiring.
• Headlights: If you have halogen H11/9005 lamps, LED retrofit “bulbs” must match the projector/reflector geometry to maintain beam pattern and cutoff. Many headlamp housings use dust caps—verify there’s clearance for LED heat sinks and route the driver box outside the cap if required. Factory LED headlamps are sealed; upgrading from halogen to the OEM LED assemblies requires swapping the complete headlamp units (left/right) and may require harness/connector changes and re‑aiming.
• DRL/PWM flicker: The truck may drive DRLs with pulse‑width modulation. Some LED retrofits will flicker without a decoder/anti‑flicker module.
• Turn signals: To prevent hyper‑flash with LED front or rear turns, use resistor kits or LED‑rated flash logic compatible with the SAM.
• Environment: Heavy‑duty duty cycles, vibration, and moisture ingress are harsher than passenger vehicles. Choose truck‑rated LEDs with robust thermal management and IP67/IP68 ratings.

How to replace each bulb

• Headlight low/high (halogen): Tilt the hood forward. From behind the headlamp, remove the rubber/plastic dust cap. Low beam (H11) and high beam (9005) twist counter‑clockwise to release; disconnect the two‑pin connector and swap. Avoid touching halogen glass. Refit the cap and re‑aim if needed.
• Headlight assembly (LED): Sealed unit. Remove the upper and lower mounting fasteners and disconnect the main harness; install the new assembly and verify aim.
• Fog lights: Access from the back side of the bumper or through the lower splash panel. H11 twists out; some LED fogs are sealed—replace the lamp assembly if failed.
• DRL: On halogen headlamps, DRL is the low beam at reduced power—no separate bulb. On LED headlamps, the DRL is an integrated LED strip/module (assembly replacement if inoperative).
• Front turn signal/parking: In the headlamp housing. Access as for the headlight; remove the turn socket, pull the 3157A/4157NA bulb straight out, and reinstall.
• Rear stop/tail/turn: On incandescent lamp housings, remove the lens screws, twist the socket, and replace 1157 bulbs. On LED tail lamps, replace the sealed lamp (usually two screws and a weather‑pack connector).
• Reverse light: Similar to tail; 1156 single‑contact in incandescent housings or sealed LED module replacement.
• License plate light: Small lens with one or two screws; 194/T10 wedge pulls straight out of the socket.
• Side markers/clearance: Wedge‑base 194 bulbs pull straight out. Many cab/hood markers are sealed 3/4" LED bullets—replace the entire marker if out.
• Interior dome/map: Pry the clear lens carefully with a trim tool. Replace 194 wedge or 31mm festoon, matching what’s installed. Test before snapping the lens back on.

Tips: Disconnect batteries before large lamp assembly swaps. Use dielectric grease on exterior bulb sockets to fight corrosion. Always verify lamp aim after any headlamp service.

Common lighting issues for this generation

• Moisture intrusion/condensation in headlamps and fog lights leading to early bulb failure or LED module corrosion. Inspect caps and seals; replace compromised housings.
• Hyper‑flash or bulb‑out warnings after LED retrofits due to low current draw—solve with CANBUS LEDs or resistors.
• Harness chafe near hood hinges and along the front crossmember causing intermittent headlamp/marker outages. Repair and add loom/edge protection.
• Melted H11 connectors from high‑wattage bulbs or poor contact. Replace pigtails and use OE‑equivalent wattage.
• Ground corrosion at frame eyelets causing dim or inoperative tail/marker lights. Clean and protect grounds with conductive anti‑corrosion compound.
• DRL/parking light flicker from PWM with non‑compatible LEDs—add decoders.
• Broken headlamp adjusters or mis‑aim after assembly replacement. Re‑aim to SAE specs to avoid glare and improve downroad visibility.

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