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Loren

ECU power steering switch purpose?

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I am running a bit low on inputs to my ecu and want to re-purpose the power steering switch input... I am assuming it's just to let the ecu increase the idle speed

slightly when the steering wheel is moved... and probably don't need it with my already very high idle. But does anyone know if it servers a more important function

than that and should be left connected? WRX GC8 btw.

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My understanding is the same as yours, that it's an idle-up to prevent the engine stalling under PS load, say if you're turning the wheels with the car stationary (which results in a lot of PS load as well).

 

Try disconnecting it at the pump end and see what happens?

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How about the ignition switch input? Seems a bit weird to have an input telling the ecu that the ignition switch is on, when it would not even have power otherwise.

 

edit...  its not an input.

Edited by Loren

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Doesn’t it turn on the fuel pump and charge the coils etc once powered up. 

Less wear to the components of it’s not always on. 

Just a guess. Depends on how much the ecu controls in that generation. 

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I was confused and thought that one of the inputs was the ignition switch... but it's not.

Used all the inputs now... if I want to add more sensors I will have to figure out the CAN comms

stuff which looks scary. Though O2 sensors have their own inputs, but have to $1000 for upgrade code

to use those... gps and accelerometers will need CAN I think.

Edited by Loren

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Can isn’t that scary from the little I’ve used it. 

 

Each thing has a unique address and broadcasts that followed by its data to everything else on the bus. 

 

Somethings like the main ecu are set to capture a set of addresses and read the data.

 

few wires and a few resistors. Mostly it’s friendly and companies make expensive connectors that make it plug and play. 

 

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You might already know but CANs a great design because the noise on each line induces an inverted signal in the other line effectively cancelling all noise. Inbetween the two ends you can splice on whatever is necessary. 

As long as you have the terminating resister between the lines at the end of each bus, 120ohms from memory, and match all the signal rates, endianness, and ids it should all go smoothly...

What ecu are you running? Sorry if it's obvious on mobile atm and haven't read much. With a good ecu you shouldnt even have to worry about any of the low level stuff anyway, just type in the correct frame ID for the sensor on the line, set the correct transmission rate and go. 

 

A CAN sniffer off ebay/aliexpress wouldn't go amiss for troubleshooting at hardware level. You can make sure you're sending out the right frames this way.

I've done a bit of work with can buses on arduinos, stm boards, and motec ecus so can field some basic questions if you have any particular ones but by no means an expert. 

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