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Webasto Thermo Top Evo 5 Diesel wiring diagram

Review how the Webasto Thermo Top Evo 5 Diesel connects, how it operates and which installation requirements apply to this model.

Open this example as a new project. Use your own parts and cable lengths to make the plan yours.

Connection and installation overview

The 31 W rating excludes coolant pump and vehicle blower; standard W-bus/RV-HD/Cronus harnesses have distinct control and separately fused branches. A generic two-wire example is not a complete system.

The 31 W rating excludes coolant pump and vehicle blower; standard W-bus/RV-HD/Cronus harnesses have distinct control and separately fused branches. A generic two-wire example is not a complete system.

Show sizes in AWG

Wiring diagram

How the Thermo Top Evo 5 D is wired.

Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.

Webasto Thermo Top Evo 5 Diesel wiring example with 1 components: Thermo Top Evo 5 D. 0 cable connections. Crossings are not junctions.Webasto Thermo Top Evo 5 Diesel. The 31 W rating excludes coolant pump and vehicle blower; standard W-bus/RV-HD/Cronus harnesses have distinct control and separately fused branches. A generic two-wire example is not a complete system. Connection overview only. Cable lengths are placeholders; use the complete manufacturer diagram to select conductors and protection. No automatic fuse or cable-size recommendation is supplied by this example.Thermo Top Evo 5 D
Webasto Thermo Top Evo 5 Diesel wiring example with 1 components: Thermo Top Evo 5 D. 0 cable connections. Crossings are not junctions.The 31 W rating excludes coolant pump and vehicle blower; standard W-bus/RV-HD/Cronus harnesses have distinct control and separately fused branches. A generic two-wire example is not a complete system. Connection overview only. Cable lengths are placeholders; use the complete manufacturer diagram to select conductors and protection. No automatic fuse or cable-size recommendation is supplied by this example.Scroll sideways to inspect all components and connections.
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Installation notes

Connections and installation requirements.

Guidance for this model, with sources linked beside the relevant advice.

Verified against the manufacturer's documentation (rev. Thermo Top Evo installation instructions 9041701A, manufacturer document hosted by Fomco), checked 2026-10-01. Manufacturer documentation →

Which heater and electrical load are represented?

This entry is the 12 V diesel Thermo Top Evo 5 kW, not the petrol model or a complete vehicle heating system. The technical tables, pages 29 and 31, give 31 W at maximum heating for the heater and 14 W for the U4847econ coolant pump. The heater figure explicitly excludes both that pump and the vehicle blower. The catalog's 31 W / 12 V calculation therefore represents only the heater's nominal running load, not startup demand or total system current.

How do the connectors differ?

The W-bus car diagram, page 20, shows the X2 power pair and the separate X1 control connector. X1 pin 2 is W-bus, pin 5 controls the vehicle blower and pin 6 serves the fuel pump. These are dedicated harness functions, not interchangeable battery terminals. Signal markers on the component preserve those distinctions without pretending to reproduce the entire loom.

The pin table, page 23, distinguishes standard car and RV/HD versions: pins 1, 3 and 4 have additional functions only in the applicable RV/HD arrangement. Do not apply an analogue on/off feed to a standard W-bus heater based on another variant's diagram.

How is the loom protected?

The car diagram includes separate F1 20 A heater and F2 30 A blower branches, with further low-current control protection. This is not one 20 A two-wire appliance. Webasto states on page 19 that the diagram's cable cross-sections apply to lengths below 4.5 m. Use the vehicle-specific installation and supplied harness to establish the actual branch layout, wire lengths and blower control.

What commissioning is required?

Route coolant, combustion air, fuel and exhaust according to the installation manual before connecting power. The first-start procedure, page 28, requires the appropriate Webasto diagnostic process, a cold enough coolant circuit to permit firing, and checks for fuel and coolant leaks. Maintain supply through the controlled shutdown sequence. The page is an overview because an isolated pair of supply wires cannot demonstrate that this heating system is complete.

Build it out

Connect it to the rest of your system.

Add Thermo Top Evo 5 D to your diagram, then connect your batteries, chargers and loads. Crimp calculates cable sizes and checks the connections as you draw.

Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.

Technical reference

Specifications, terminals and supporting parts.

Check the model, ratings and connection points against your own unit before choosing installation hardware.

Catalog specification

Compatible systems
12 V
Rated power
31 W
Continuous draw
2.6 A

Supporting parts

  1. A lug or terminal to match each post on the part
  2. Strain relief and boots so nothing chafes or shorts
  3. Cable and fuses sized once the whole system is drawn

Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.

Terminal map

Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.

X2/1 +

pos

positive · input

—

X2/2 −

neg

negative · input

—

X1/2 W-bus

wbus

signal · bidi

—

X1/5 blower control

blower

signal · bidi

—

X1/6 fuel pump

fuel

signal · bidi

—

A dash means a current rating is not specified here.

Method & provenance

Where the specifications and sizing come from.

Manufacturer specifications describe the equipment. Crimp calculates cable results from the circuit and assumptions you enter.

From the maker

What the catalog says

Manufacturer, model, ratings and which terminal does what come from the catalog. A newer revision, or the nameplate on the unit in your hand, can say something different — when it does, the nameplate wins.

ABYC E-11

What Crimp worked out

Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. The run length and the current above are what drive the result. Crimp doesn't know how warm your space gets; draw the cable inside an engine-bay zone on the canvas and it sizes for the heat.

Read how the sizing works

Next step

Plan your installation with Thermo Top Evo 5 D.

Open this example as a new project. Add your equipment and cable lengths, then review the sizing and checks for your setup.