2016 Peterbilt 389 — Fuse Box Diagram & Amperage

Quick answer

• Driver dash/kick‑panel fuse/relay panel (cab PDM): Primary interior fuse box behind the left lower dash panel by the driver’s left knee. Covers ignition feeds, lighting control, HVAC blower, radio/12V outlets, trailer lighting/trailer brake controller triggers, wipers, and many relay coils.
• Engine‑bay power distribution center (PDC): Under the hood on the left frame rail/inner fender or firewall (varies by build). Protects ECM/engine electronics, fuel lift pump, headlamp power, ABS modulator, A/C clutch, horn, and starter relay.
• Sleeper/bunk fuse block (if equipped): In the sleeper cabinet or behind a trim panel on the bunk wall. Handles sleeper blower, dome/reading lights, 12V outlets, refrigerator/inverter feeds, and auxiliary heater.
• Battery/junction/megafuse block: In or near the left‑side battery box. High‑amperage MEGA/MAXI fuses for alternator, main cab PDM feed, inverter, and chassis circuits. Not a small‑blade fuse panel, but critical to no‑power complaints.

Note: Peterbilt harness options vary by VIN and engine (PACCAR MX‑13 vs. Cummins). Use the diagram printed on your fuse lid as final authority.

Driver dash/kick‑panel fuse/relay panel (cab PDM)

Below is the most common 2016 389 cab PDM coverage. Fuse positions/numbers differ by specification. Verify against the legend in the panel door.

Relays typically in this panel: headlamp high/low, blower motor, wiper, trailer marker, ignition run, and A/C clutch relay (coil feed here, power relay may be in PDC).

Engine‑bay power distribution center (PDC)

Common under‑hood protection for engine and chassis loads. Exact cavity numbers vary. Always confirm the printed legend on the PDC cover.

Relays typically here: starter relay, headlamp feed, A/C clutch, horn, fan clutch, DEF heater/pump, ABS power. Some builds combine these with maxi fuses in a sealed PDM on the left frame rail.

Sleeper/bunk fuse block (if equipped)

Bunk equipment varies; these are the usual protected circuits on 389 sleepers. Check the legend inside the sleeper panel.

Relays: sleeper blower speed, auxiliary heater, inverter enable (varies by option).

Battery/junction/megafuse block

High‑amperage protection mounted in or near the left battery box. These are MEGA/MAXI fuses or fusible links feeding entire systems. Use the stamping on each fuse holder as the reference.

Relays: not typical here; this is a high‑current junction.

How to test a fuse

• Visual check: Pull the suspect fuse with a puller. If the metal link is melted, replace it. This can miss hairline breaks—don’t rely on sight alone.
• Test light method: Key on. Back‑probe the two test tabs on top of the fuse. Both sides should light a test light. If only one side lights, the fuse is open.
• Multimeter method: With key on, you should read battery voltage on both tabs to ground. Or, remove the fuse and check continuity across the blades (0–1 Ω good; OL/open is blown).
• After replacement: If the new fuse pops immediately, you have a short to ground in the circuit or a failed component. Do not upsize the fuse.

Common blown fuses on this vehicle (what to check first)

• 12V power/cigar lighter (20A yellow): Coins or metal USB adapters short the socket. Inspect the socket and harness behind the dash panel.
• Headlamps low/high (15A blue/relay feed): Hood‑to‑cab harness flex point near the left hood hinge is a known chafe spot. Inspect for rubbed insulation.
• HVAC blower (30A green): Seized blower motor or melted resistor/connector. Spin the blower by hand and check current draw; inspect the resistor pack if equipped.
• Trailer lighting feeds (15–20A): Shorts in the 7‑way at the rear or water intrusion in the trailer pigtail. Test with the trailer unplugged—if the fuse holds, fault is in the trailer.
• ABS power (30–40A): Corroded frame‑rail connectors or water in the modulator. Scan for codes before replacing fuses repeatedly.
• ECM/engine electronics (10–30A): Usually blown by chafed sensor wiring on the engine or DEF harness. Don’t condemn the ECM first—inspect harnesses.

Notes

• The 389 typically does not have SRS airbags; “airbag” references in some charts pertain to suspension air bags, which are air‑valve controlled, not fused like SRS systems.
• Fuse numbering and cavity locations vary widely with build specs. Always confirm the exact fuse position and label printed inside your panel cover or in the Peterbilt chassis electrical manual for your VIN.

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