Removing sub-systems from Gen4 ECU

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Removing sub-systems from Gen4 ECU

Postby dan_ashcroft » Sun Apr 15, 2018 8:07 pm

Asking the tuner gurus as I think you will probably have best knowledge of how the ECU works.

Want to swap a different (lighter) shell around my 3RB drivetrain. Since I have a complete running car, I am thinking of smoothing it out by dropping the sub-systems I don't plan on running before I do the swap. Does this sound feasible? FYI, current plan is into LX Gen2 (wind up windows, no central locking) and plan on swapping the loom and instrument cluster over into it. Things I won't need and plan on removing behind is ABS, airbags, aircon (will use Gen2 non-smart aircon - can't wait), central locking etc.

Does the ECU look for sub-systems, IE if stuff isn't there will it throw errors, or will it not notice? I imagine that the immobilizer module might be the biggest problem, ie if it can't contact it, then something bad must be happening, therefore don't start engine? (Although if physically possible I'm not against swapping the immobilizer RFID ring over if it simplifies things.)

Not done this before so there may be something glaringly obvious that I have missed, or will it be as simple as just identifying and then unplugging sub-systems?
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Re: Removing sub-systems from Gen4 ECU

Postby lib2004RB » Thu Apr 19, 2018 10:40 am

Immobiliser system(or BIU(body Integrated System)) needs to talk to Dash Cluster, ECU and Key(RFID).
At factory these are all synced together with SSM (Subaru Select monitor) before it will start.
So you will need all from the same matching car.

All these systems talk on the CAN BUS.
So all are integrated, including lighting, air con, central locking, cruise control etc.

The speedometer wont work as you need the matching ABS system.
As the speed reference is taken from the ABS system.
Rev gauge, temp, Engine light all run over can bus.


You could try the subatronics can bus emulator to get it running.
http://www.subarugears.com/subatronics/About.html

Or aftermarket ECU.
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Re: Removing sub-systems from Gen4 ECU

Postby Liam » Sun Aug 14, 2022 1:05 pm

Just for reference, techo(rev guage) has a pink wire fromt the ecu to the cluster. Engine light isn’t canbus either it uses a orange and white wire as an output from the ecu.
Cruise control isn’t canbus it’s via 3 wires 2 for resistances and ones a signal ground.
Lighting is via the bcm and works weather these is an ecu cluster etc or not.
Coolant temp and I think wheel speed is canbus however.
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