# 21778587 Wiring Harness | Genuine Volvo Penta Part

## 🔧 Product Description

Factory wiring harness for the D13B-E MG relay, cable and fuse installation. Connector housings, terminal positions and circuit lengths are configuration controlled and must match the engine electrical specification.

## 🚤 Compatibility

Typically suits:

-   Volvo Penta D13B-L MP
-   Volvo Penta D13B-M MP

-   **Engine Family:** D

## ⚙️ Key Features

-   OEM connector keying and pinout
-   Correct conductor size and insulation
-   Factory branch lengths and routing
-   Sealed connectors where required
-   EVC / voltage configuration controlled

## 🔌 Function

Distributes power, ground and control signals between the assigned electrical components.

## ⚠️ Common Signs of Failure

-   Intermittent faults when the harness is moved
-   Corroded, bent or backed-out terminals
-   Damaged insulation or chafed conductors
-   Water entry at connector seals

## 🛠️ Service Notes

-   Compare the new harness with the old one before fitting — check the connector types, the number of pins and the branch lengths, and lay it out alongside the old loom to confirm every branch reaches its component
-   Disconnect the batteries before unplugging or fitting a harness, and support the loom as you work so its weight never hangs on a connector or a bulkhead grommet
-   Route it along the original path and secure it with the original clips and ties, clear of hot exhaust surfaces, sharp edges and anything that moves; leave a service loop at each connector rather than pulling a branch tight
-   Push every connector home until the lock latches and protect the joints with a marine dielectric grease — an intermittent electrical fault is far more often a partly seated or salt-corroded pin than a broken wire
-   Renewing the harness is the right repair where insulation is chafed, brittle or oil-soaked, or where corrosion has tracked inside the connector bodies; patch repairs in a damp engine bay tend to fail again, and any single conductor that is repaired should be joined with tinned marine cable of the same gauge, a proper crimp and adhesive-lined heat-shrink

## 🔄 Supersession & Cross Reference

### OEM / Related Numbers

-   3587173 - relay box
-   3587172 - relay socket
-   3171420 - relay
-   874432 - related connector housings
-   20429844 - related connector housings
-   20429843 - related connector housings
-   20429842 - related connector housings

## 📦 Condition

-   Genuine Volvo Penta part
-   Brand new
-   Supplied in original or equivalent packaging

## Details

- **Price:** 5943.3 AUD
- **Vendor:** Volvo Penta
- **Type:** Electrical & Wiring
- **Tags:** Volvo Penta

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 5943.30 AUD | In stock |

## Images

- 21778587 Wiring Harness | Genuine Volvo Penta Part
- 21778587 Wiring Harness | Genuine Volvo Penta Part - photo 2 of 2

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/21778587-wiring-harness-genuine-volvo-penta)
> Updated: 2026-09-06