2016 Peterbilt 579 — Fuse Box Diagram & Amperage
Locations, circuits protected, common ratings, and relay callouts
AI-generated reference. Always verify torque values, fluid capacities, intervals, and procedures against the manufacturer's service manual or OEM repair information before performing work. Repairius is not liable for damage from acting on this content without verification.
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Quick answer
- Under-hood power distribution module (PDM): Driver-side engine bay on the left inner fender/behind the headlamp area under a plastic cover. Houses high-current MAXI/MIDI fuses, standard blade fuses, and several relays (starter, headlamps, A/C, fan).
- Driver dash/kick-panel fuse block: Lower left dash, behind the removable kick-panel/trim by the driver’s left knee. Contains most cab/accessory fuses and multiple control relays (blower, wiper, IGN/ACC).
- Sleeper/bunk fuse panel (if equipped): In the sleeper, typically under the lower bunk access panel or in the right-rear cabinet. Feeds sleeper HVAC, lights, 12V outlets, inverter/aux options. Note: There is no “trunk” on this vehicle.
Important: Peterbilt builds are highly optioned; fuse numbering and cavity assignments vary by VIN and PDM revision. Use the printed legend on the fuse-box lid and your VIN-specific diagram to confirm exact cavity numbers. The tables below list the most common circuits and typical amperages/colors found on 2016 579 models.
Under-hood Power Distribution Module (PDM)
Typical relays in this box: Starter relay, Headlamp (low/high) relays, A/C compressor clutch relay, Engine fan/clutch relay, Trailer ABS power relay (if equipped).
Note: Fuse numbers/positions vary by build; verify the lid legend. Amperages and color codes shown are common values.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| Varies (see lid) | 20A | Yellow | ECM/PCM Battery Feed |
| Varies (see lid) | 10–15A | Red/Blue | ECM/PCM Ignition Feed |
| Varies (see lid) | 20–30A | Yellow/Green | Fuel Pump or Fuel Primer (diesel) |
| Varies (see lid) | 10–15A | Red/Blue | A/C Compressor Clutch |
| Varies (see lid) | 15–20A | Blue/Yellow | Headlights – Low Beam (L/R split on some builds) |
| Varies (see lid) | 15–20A | Blue/Yellow | Headlights – High Beam (L/R split on some builds) |
| Varies (see lid) | 10–15A | Red/Blue | Front Park/Marker Lamps |
| Varies (see lid) | 20–30A | Yellow/Green | ABS Module Power (tractor) |
| Varies (see lid) | 30–40A (MAXI) | Green/Orange | Blower Motor (some builds under-hood, others in dash block) |
| Varies (see lid) | 30–60A (MAXI/MIDI) | Green/Orange | Trailer Brake Power/Controller Supply (if tractor-wired) |
| Varies (see lid) | 30–60A (MAXI/MIDI) | Green/Orange | Trailer ABS Constant Power (if equipped) |
| Varies (see lid) | 30–40A (MAXI) | Green/Orange | Cooling Fan/Clutch Solenoid Feed |
| Varies (see lid) | 10–15A | Red/Blue | Horn/Front Auxiliary |
Driver Dash/Kick-Panel Fuse Block
Typical relays in this block: Blower motor relay, IGN/ACC relay, Wiper hi/lo relays, Headlamp control relay (varies), Trailer brake control relay (if equipped).
Note: Numbers differ by trim; confirm with the cover legend. Below are common cab circuits and ratings.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| Varies (see lid) | 10–15A | Red/Blue | Ignition/ACC Feed to Switch, Cluster, and Body Controllers |
| Varies (see lid) | 15A | Blue | Radio/Infotainment, Clock/Memory |
| Varies (see lid) | 20A | Yellow | Cigar Lighter/12V Power Outlets (dash sockets) |
| Varies (see lid) | 7.5–10A | Tan/Red | Instrument Cluster/Warning Indicators |
| Varies (see lid) | 25–30A | Clear/Green | Blower Motor (cab) |
| Varies (see lid) | 10–15A | Red/Blue | HVAC Control Module |
| Varies (see lid) | 15–20A | Blue/Yellow | Wipers/Washers |
| Varies (see lid) | 10A | Red | Brake Light Switch/CHMSL (tractor) |
| Varies (see lid) | 10–15A | Red/Blue | Interior Dome/Map Lamps |
| Varies (see lid) | 10–15A | Red/Blue | Power Mirrors/Windows (if equipped) |
| Varies (see lid) | 10–15A | Red/Blue | Trailer Brake Control Signal/Stop Lamp Feed (if equipped) |
| Varies (see lid) | 10–20A | Red/Yellow | ABS Control/Signal (cab side) |
| Varies (see lid) | 10A | Red | Airbag/SRS (rare on Class 8; if equipped) |
Sleeper/Bunk Fuse Panel (if equipped)
Typical relays in this area: Sleeper blower relay, Sleeper A/C or auxiliary heater relay (Espar/Webasto if equipped), Inverter enable relay, Sleeper lighting relay.
Location note: Often under the lower bunk panel or in the right-rear sleeper cabinet behind a trim cover. Check the inside of the cover for the fuse legend used on your VIN.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| Varies (see lid) | 15–25A | Blue/Clear | Sleeper Blower Motor |
| Varies (see lid) | 10–15A | Red/Blue | Sleeper HVAC Control/Panel |
| Varies (see lid) | 15–20A | Blue/Yellow | Sleeper A/C Clutch or Aux Heater Feed (if equipped) |
| Varies (see lid) | 10–15A | Red/Blue | Sleeper Dome/Reading Lights |
| Varies (see lid) | 15–20A | Blue/Yellow | Sleeper 12V/Cigar Outlets |
| Varies (see lid) | 20–30A | Yellow/Green | Refrigerator/Appliance Outlet (if equipped) |
| Varies (see lid) | 30–60A (MAXI/MIDI) | Green/Orange | Inverter/Power Point (option) |
How to test a fuse
- Visual check: With the key off, pull the suspect fuse and look for a melted/broken element. Re-seat fully if it’s good.
- Test light method: Leave the fuse installed. With the key in the required position for that circuit, probe the two test tabs on top of the fuse. Both sides should light. If only one side lights, the fuse is blown.
- Multimeter continuity: Remove the fuse and check ohms across the blades. Near 0 ohms = good; OL/open = blown.
- Replace correctly: Use the same amp rating and type (mini/ATO/MAXI). Color codes help: 10A Red, 15A Blue, 20A Yellow, 25A Clear/White, 30A Green, larger MAXI/MIDI often Green (30A), Orange (40A), etc.
- Root cause: If a new fuse blows immediately, find the shorted component or chafed wiring before upsizing any fuse (never install a larger fuse than specified).
Common blown fuses on this vehicle (what to check first)
- 12V/cigar outlet (20A Yellow): Coins, adapters, or metal shavings can short the socket. Inspect the socket and any USB adapters.
- Radio/infotainment (15A Blue): Pinched harness during radio swaps or aftermarket CB/telematics tapping the same feed. Verify proper grounds and remove add-on taps.
- Headlamp low/high (15–20A): Look for chafed wiring near the hood hinge, headlamp buckets, and behind the bumper. Check bulb wattage—over-watt bulbs can overload.
- Blower motor (25–30A): A seizing blower or debris in the squirrel cage spikes current. Spin the blower by hand, check for water intrusion, verify the blower relay.
- A/C clutch (10–15A): Shorted clutch coil or rubbed clutch feed wire at the compressor. Check coil resistance and inspect the harness near the compressor bracket.
- ABS (30A): Trailer pigtail or tractor frame harness chafing. Inspect 7-way socket wiring and the ABS power lead along the frame rails.
- Trailer brake power (30–60A MAXI/MIDI): Shorts in the trailer or corroded connector bodies. Try with a known-good trailer to isolate.
- ECM feeds (10–20A): Uncommon, but if blown, inspect harness runs along the left frame rail, around the EGR/DEF components, and at the PDM for water intrusion.
Reminder: Fuse cavity numbers and assignments vary by VIN, option content, and PDM revision. Always confirm against the printed legend inside the fuse panel cover and your Peterbilt wiring diagram.
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Before you pull a fuse on the 2016 Peterbilt 579
- Use the label printed on the panel cover or the owner's manual for your exact build. Layouts change with options, model year and build date, so a chart for another truck can be wrong.
- Replace a blown fuse only with the same amp rating. A larger fuse can let wiring overheat.
- A fuse that blows again right away means a short or failing component downstream. Find the cause before replacing it again.
- A good fuse doesn't prove the circuit works — relays, grounds and connectors fail too.
- Many heavy trucks have more than one power distribution point (cab, under-hood or near the batteries), and some circuits use circuit breakers instead of fuses. Some systems have 24-volt starting circuits; confirm the voltage before testing.
- Disconnect the battery before working near high-current fuses or cables.
Learn more: How fuses, relays and truck electrical systems work · Find mobile truck repair
More specs for the 2016 Peterbilt 579
Oil Capacity & Filter
Capacity, weight, filter PN, drain plug torque, change interval.
Fluid Type Specs
Engine oil, coolant, ATF, diff, brake, PS, DEF — with OEM spec numbers.
Coolant Capacity & Type
Total system capacity, OEM coolant spec, flush interval, bleed tips.
Transmission Fluid & Service
Trans model, fluid spec, capacity, filter PN, service interval.
Torque Specifications
Lug nuts, drain plug, caliper, axle nut, plug, key fasteners.
Brake Pad & Rotor Specs
Pad PNs, rotor size, min thickness, caliper torque.
Tire Size & Pressure
OEM size, cold psi, bolt pattern, wheel size, TPMS.
Battery Size & Group
Group size, CCA, AGM/flooded, dimensions, reset note.
A/C Refrigerant & Oil
R-134a or R-1234yf, charge oz, PAG oil spec.
Bulb Sizes (Headlight, Tail, Fog)
Headlight, fog, tail, turn, reverse, interior.
Factory Maintenance Schedule
Service intervals by mileage, severe-duty notes, known issues.
Towing Capacity & Payload
Max tow, payload, GVWR/GCWR, hitch class by trim.
Serpentine Belt Routing & Length
Belt routing, length, rib count, OEM + aftermarket PNs.
Wheel Alignment Specifications
Camber, caster, toe ranges (front & rear), adjustability notes.
Paint Color Codes
All factory colors with paint codes, sticker location, touch-up tips.
Wiper Blade Sizes
Driver/passenger/rear blade size, attachment, OEM + cross-refs.
Spark Plug Type & Gap
Plug PN, gap, torque, interval by engine.
Transmission & Axle Gear Ratios
Trans gear ratios, axle ratios, RPO codes, tow vs MPG impact.
Key Fob Programming
DIY programming steps, FCC ID, fob PN, battery, transponder.
Same spec — other model years
Maintenance & repair guides
2016 Peterbilt 579 Maintenance Schedule →
Available maintenance guidance; confirm the manufacturer schedule.
Repair planning references →
Plan the scope of work; detailed procedures need configuration-matched evidence.
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