MaxxECU PDM20: Replace Your Fuse Box and Relay Bank With Software

Quick answer: The MaxxECU PDM20 is a power distribution module that replaces traditional fuses and relays with 20 programmable outputs — 8 × 25 A, 8 × 15 A and 4 × 8 A — handling up to 230 A total throughput. Every output is PWM-capable up to 20 kHz, measures its own current and voltage, and is protected by an emulated fuse characteristic with hardware backup and automatic restart. It has 7 digital/analog 0–24 V inputs, 6 outputs with H-bridge drivers, a monitored +5 V sensor supply, CAN keypad support (4, 6, 8 or 12 keys), and an energy-saving mode drawing just 0.004 A. It is set up entirely from the MTune PC software over CAN — the same software you tune the engine in — and works with every MaxxECU device.

Rocket Speed Shop is the official MaxxECU distributor for the Baltics. This guide explains what a PDM actually buys you and which builds justify one.

Why replace fuses and relays at all?

A conventional loom carries a fuse box, a bank of relays, and a wire from each of them to each load. Every one of those is a physical failure point, and none of them tells you anything. A blown fuse in the middle of a race weekend is a diagnostic exercise with a torch.

A PDM changes the model. One heavy cable goes from the battery to the PDM. Each load gets one wire from the PDM. Everything else — which output turns on, when, under what conditions, at what current limit, at what duty cycle — is software. And every output reports its own current draw back to you, live and in the log.

Practical consequences:

• Far less wire. No relay panel, no fuse box, no duplicated feeds. On a stripped race car this is measurable weight and a genuinely simpler loom.
• Failures become visible. An output that has tripped tells you it tripped, with an error code, instead of silently going dead.
• Overcurrent protection you can tune. Levels are adjustable, with automatic restart and a soft-start option for inrush loads like fans and pumps. Warning levels can be set for both over- and under-current, so a pump that is drawing less than expected also raises a flag.
• PWM everything. Fan speed control, fuel pump duty control, dimmed lighting — all directly from an output, no external controller.
• A keypad instead of a switch panel. CAN keypads with 4, 6, 8 or 12 keys replace the toggle switches and their wiring entirely.
• Outputs can be paired to increase current capacity where one channel is not enough.

Who the MaxxECU PDM20 is for

• Any car being rewired from scratch. This is the moment a PDM pays for itself — you are already buying wire, fuses, relays and a switch panel.
• Race and rally cars where reliability, diagnosability and weight all matter and a pit-lane electrical fault costs a result.
• Engine swap projects that no longer have a coherent factory loom to work with.
• High-current builds — twin fuel pumps, electric water pumps, electric power steering, big cooling fans. 230 A of throughput with per-channel monitoring.
• Anyone already running MaxxECU — the PDM20 configures inside MTune over CAN, so there is no second piece of software to learn.

MaxxECU PDM20 full specifications

Which MaxxECU should you pair it with?

The PDM20 works with every MaxxECU, from the smallest to the flagship. What changes is the balance of the build.

With MINI or STREET

These ECUs have only 4 general-purpose outputs each. A PDM20 transforms them — suddenly the ECU is doing fuel and ignition while the PDM handles every switched load with proper current monitoring. If you are choosing between a STREET plus a PDM20 and a bigger ECU for output count alone, the PDM route is usually the better system.

With SPORT or RACE

The natural pairing for a track or drift car. SPORT has 7 GP outputs and RACE has 9 low-side plus 2 sourcing; the PDM20 adds 20 more with per-channel diagnostics and a keypad instead of a switch panel.

With GEN2 TRACK or GEN2 RACE

The PDM20 uses Superseal connectors, the same family GEN2 ECUs use, so the two build into one coherent loom. GEN2's dual CAN means the PDM can sit on its own bus, separate from gearbox and OEM traffic.

With PRO

PRO already has 30 general-purpose outputs, so the PDM20 is less about count and more about current capacity, per-channel monitoring and the keypad. On a serious drag or endurance car both still make sense together.

Related products worth considering

• MaxxECU Expansion Module — the PDM20 handles power. The Expansion Module handles signals: 12 analog inputs, 4 pulse inputs, 4 × 12 V outputs and 4 H-bridges over CAN. If you are short on inputs rather than short on switched power, this is the module you want.
• CAN keypad — 4, 6, 8 or 12 keys, replacing a switch panel and its loom.
• PDM20 terminated harnesses — harness 1 (34-pin) and harness 2 (26-pin) are available pre-terminated, which saves a substantial amount of crimping.
• Terminated engine harness — if you are rewiring the car anyway, doing the engine side with a pre-terminated harness at the same time is the sensible order of operations.

Frequently asked questions

What does a PDM actually do?

A power distribution module replaces the fuse box and relay bank. One heavy feed comes in from the battery; each load gets one wire out. Which outputs turn on, under what conditions, at what current limit and at what PWM duty is all defined in software, and each output measures and reports its own current.

Does the MaxxECU PDM20 work with any MaxxECU?

Yes — all MaxxECU devices, from MINI to GEN2 RACE. It communicates over CAN and is configured from the MTune PC software through any MaxxECU.

How much current can the PDM20 handle?

230 A total throughput, split across 8 outputs at 25 A, 8 at 15 A and 4 at 8 A. Outputs can be paired to increase capacity on a single load.

Can the PDM20 control fan speed?

Yes. Every one of the 20 outputs is PWM-capable up to 20 kHz, so variable-speed fans, dimmable lighting and duty-controlled fuel pumps are all handled natively.

What happens when an output overloads?

The output trips on an emulated fuse characteristic with hardware backup protection, raises an error code, and can automatically restart. Levels are adjustable and a soft-start option handles high inrush loads.

Does the PDM20 drain the battery when the car is parked?

Barely. The built-in energy-saving mode draws 0.004 A.

Can I use a keypad instead of switches?

Yes. The PDM20 supports CAN keypads with 4, 6, 8 or 12 keys, which removes a switch panel and its wiring from the car entirely.

Where can I buy a MaxxECU PDM20 in the Baltics?

Rocket Speed Shop is the official MaxxECU distributor for Estonia, Latvia and Lithuania.

Explore the rest of the MaxxECU range

MINI · STREET · SPORT · RACE · GEN2 TRACK · GEN2 RACE · PRO · Expansion Module.

Shop MaxxECU PDM20 at Rocket Speed Shop →