ECU Master system wiring with MSEL Isolator

I'm installing an ECU Master PDM16, EMU Black and ADU5 along with an MSEL Isolator. I'm just trying to clarify one wiring issue. Both the ECU and ADU have a 12v+ battery and 12v+ switched. What is the best way to wire this. I believe this is so the ECU and ADU can shut down and start up properly and hold memory.

If i wire these both to the PDM they will fully cut power on Isolator shutdown switch. Is there a preferred way to do this?

Many Thanks Graeme

Hey Graeme,

The isolator will have a PDM/ECU control output (often called an “engine run” or “shutdown” signal). The purpose of this is to tell the ECU and/or PDM that the battery is about to be isolated, giving them time to shut down properly before power is physically cut.

In your setup, the PDM will typically be supplying both constant 12V (battery) and switched/ignition 12V to the ECU and ADU. The best approach is to wire the isolator’s control output into the PDM as an input, and configure that as an isolator/kill switch trigger. When activated, the PDM can then shut down its switched (ignition) outputs in a controlled way before the battery is disconnected.

It’s also good practice to feed that signal into the ECU as well. One of the key reasons for this is to allow the ECU to shut the engine down cleanly before the alternator is disconnected from the battery while still generating current. That situation can cause voltage spikes, which is what you’re trying to avoid.

If the PDM removes switched (ignition) power to the ECU and ADU in response to the isolator signal, you effectively achieve the same safe shutdown outcome, everything powers down cleanly before the hard isolation happens.

So in short:

Isolator PDM/ECU output → PDM input (primary control)Optional but recommended → also feed ECU input directlyPDM cuts switched (ignition) 12V and handles controlled shutdown of ECU/ADU before full isolation

That way you retain proper memory, clean shutdown, and protect the electronics from voltage spikes.

Thats great Caleb. Makes sense.

Just need to reconfigure a few outputs to make that work.

Cheers

Graeme