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The mkiv Supra Owners Club

5v power feed??


Jim_1979

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Didn't think there was one?? I thought everything was 12v - just different wattage?

 

Not that i know of.

Wattage is the measure of the power that the different electrical components consume.

Everythings 12v, or 14.4v when the car is running :)

The ecu looks for 0-5v inputs off stuff (like boost input etc) but you could never tap in to any of this as it would affect the input the ecu see's.

you could get a variable power supply from maplin or something which uses a 12-15v dc input, just make sure that the power supply can give out the amps that you 5v device needs.

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as mad as it may sounds... that's what it does. Taps into an ECU connection to get the 5volts!

 

 

It is a wrong type of Fcd then as jake says?

 

You didnt say what it was on your original post:p

 

I dont think the ecu does have any 5v outs, only 0-5v in's.

Its probably not worth the hassle mate, sell the fcd, and buy the right type :)

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why don't you just fit a line regulator in the 12 volt feed to cap the voltage at 5 volts. i'll try and get you a RS part number for one:)

 

 

here you go

 

 

FARNELL part number for 5v regulator LM7805 412-776 (price 37p

 

you also will require two capacitors to stabilize the voltage one on each end of the LM7805 regulator part number

FARNELL 123-6657 (10uF)

 

this setup will be fine for up to 1amp which i think is more than you require.

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Yeah mate.. thanks.

 

I think that's actually where it's supposed to be wired into for the 5v. It's supposed to be wired into the Vc pin on the mr2 (5v) (this is originally a Mr2 fcd).

 

On the mr2 it's supposed to be connected to the TPS (Turbo pressure sensor) and the Vc pin (+5v) and an earth.

 

I'll get a multimeter out tomorrow/thursday and see what's what. I'll also let you know if it works or if fuel cut still kicks in.

 

I'll test it first without fitting it to make sure the Fuel Cut does kick in (just fitted double decat/exhaust and restrictor ring), then once it's fitted.

 

If it doesn't work it'll get binned and buy another one. If it works on the mr2 wired up like this, then tbh I don't see why it wouldn't on the supra.

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The ECU does have 5v outputs and one the MAP sensor does use 5v.

I would try to find out what current this device is likely to draw, as I doubt the 5v output from the ECU will ba able to sink very much.

It may be better to use absxxx suggestion. At least that way you won't damage the ECU.

 

Or just get a decent FCD. ;)

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this setup will be fine for up to 1amp which i think is more than you require.

 

Probably not 1A without a heatsink on the 7805, though? I havnt read the specs for that particular part, but since you will be dumping 7W into it at 1A I would have thought it would start to get a tad hot.

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The ECU does have 5v outputs and one the MAP sensor does use 5v.

I would try to find out what current this device is likely to draw, as I doubt the 5v output from the ECU will ba able to sink very much.

It may be better to use absxxx suggestion. At least that way you won't damage the ECU.

 

Or just get a decent FCD. ;)

 

from the seller....

 

"the fcd doesnt draw any current. Basically what it does is it leaks an adjustable amount of voltage away from the boost sensor signal to ecu wire stopping the ecu seeing 5volts which is what trips the fuel cut. I hope this helps.

Regards Kelly"

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