2019 Peterbilt 579 Fuse Box Diagram & Amperage
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Quick answer
On the 2019 Peterbilt 579, you'll find the primary fuse box inside the cab, on the passenger side. To access it, open the passenger-side door and look at the kick panel/footwell area. The fuse panel is located behind a protective cover. Unlike some passenger vehicles, the Peterbilt 579 consolidates most of its fuses and relays into this single, accessible panel, so you won't typically find additional fuse boxes under the hood or in a separate trunk/cargo area.
Always confirm the fuse layout by checking the diagram printed on the inside of the fuse box cover, as configurations can change slightly based on the truck's specific options and build date.
Main Fuse Box (Passenger-Side Dash)
This central fuse and relay center houses the components for nearly all of the truck's primary electrical systems. Below is a common configuration for a 2019 Peterbilt 579. Note that your truck's layout may vary slightly depending on optional equipment.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| F1 | 10A | Red | Ignition Switch, Keypad |
| F2 | 15A | Blue | Headlights, Low Beam (Left) |
| F3 | 15A | Blue | Headlights, Low Beam (Right) |
| F4 | 10A | Red | Marker Lights, Roof |
| F5 | 20A | Yellow | Trailer Marker Lights |
| F6 | 15A | Blue | Park & Tail Lights |
| F7 | 10A | Red | Dash Illumination |
| F8 | 30A | Green | Blower Motor, HVAC Controls |
| F9 | 15A | Blue | A/C Clutch |
| F10 | 10A | Red | Engine Control Module (ECM) - Ignition |
| F11 | 30A | Green | Engine Control Module (ECM) - Battery |
| F12 | 20A | Yellow | Fuel Pump, Fuel Heater |
| F13 | 15A | Blue | Ignition Coils / System |
| F14 | 10A | Red | Airbag / Safety Restraint System (SRS) |
| F15 | 20A | Yellow | ABS Control Module |
| F16 | 10A | Red | Transmission Control Module (TCM) |
| F17 | 25A | Natural | Trailer Brake Controller |
| F18 | 15A | Blue | Radio, Infotainment System |
| F19 | 20A | Yellow | Cigar Lighter / 12V Power Outlet 1 |
| F20 | 20A | Yellow | 12V Power Outlet 2 |
| F21 | 10A | Red | Instrument Cluster |
| F22 | 15A | Blue | Stop Lights / Brake Switch |
| F23 | 30A | Green | Sleeper Power |
| F38 | 15A | Blue | Headlights, High Beam (Left) |
| F39 | 15A | Blue | Headlights, High Beam (Right) |
Relay Locations (Common)
Relays are typically located in the same panel, often grouped together. Refer to the diagram on your fuse panel cover to identify the exact relay.
- R1: Starter Relay
- R2: Ignition Main Relay
- R3: HVAC Blower Motor Relay
- R4: A/C Clutch Relay
- R5: Headlight Relay
- R6: Fuel Pump Relay
- R7: Park/Neutral Relay
How to test a fuse
Testing a fuse is a quick and simple way to diagnose an electrical problem. You'll need a fuse puller (often included in the fuse box) and either a multimeter or a test light.
- Safety First: Turn the truck's ignition completely off.
- Locate & Remove: Find the fuse box on the passenger-side kick panel. Identify the suspect fuse using the diagram on the cover. Use the fuse puller to gently remove it.
- Visual Inspection: Hold the fuse up to the light. Inside the plastic body, you'll see a small metal strip. If this strip is broken or burned, the fuse is blown and needs to be replaced.
- Multimeter Test (Recommended): For a more definitive test, set your multimeter to the continuity setting (it often looks like a sound wave symbol). Touch one probe to each metal blade on the top of the fuse. If the multimeter beeps or shows a reading of near-zero ohms, the fuse is good. If it remains silent or reads 'OL' (Open Loop), the fuse is blown.
- Replacement: If the fuse is blown, replace it with a new fuse of the exact same amperage rating. Using a higher-amperage fuse can cause a fire hazard by allowing too much current through the circuit.
Common blown fuses on this vehicle
-
Fuse F19/F20 (Cigar Lighter / 12V Power Outlet): This is one of the most frequently blown fuses, usually caused by plugging in a faulty phone charger, a high-draw device like a coffee maker, or a foreign object (like a coin) falling into the outlet socket. What to check first: Inspect the outlet for any foreign objects. Unplug all devices and try a new fuse. If it blows immediately, the outlet itself may have a short.
-
Fuse F5 (Trailer Marker Lights): Trailer wiring is a common source of electrical issues. A short in the trailer's wiring harness or a corroded connector can easily blow this fuse. What to check first: Disconnect the trailer. Replace the fuse and see if the truck's own marker lights work. If they do, the problem is almost certainly in the trailer's wiring.
-
Fuse F8 (Blower Motor): If your HVAC fan stops working on all speeds, this fuse is the first place to look. This fuse can blow if the blower motor is old and beginning to fail, causing it to draw too much current. What to check first: Listen for any grinding or squealing noises from the fan before it failed. If the fuse blows again after replacement, the blower motor or the blower motor resistor likely needs to be inspected or replaced.
-
Fuse F2/F3 (Headlights): While less common, a headlight fuse can blow when a bulb burns out and creates a momentary short. What to check first: Check if the corresponding headlight bulb has burned out. Replace the bulb, then replace the fuse.
If you've checked these common issues and are still struggling to diagnose an electrical problem, it may be time to consult a professional. Electrical systems in modern trucks are complex, and an expert can save you time and prevent further damage.
Find a trusted shop on Repairius.
Before you pull a fuse on the 2019 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 2019 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
2019 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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