I'm looking at the FSM at wires 1a, 1b, and 1c on the S5 turbo ecu

1a "battery" costant 12v
1b "main relay" key on 12v. key off 0v
1c "ign switch" key start 12v. key on ov. key off ov.

does anyone know how much current these draw? does 1a take all the power. and 1b and 1c are just low curent "remote turn on wires" like a car amp? or do 1b and 1c carry current as well?

by looking at his. I'm assuming that 1b turns on the ecu when the key is on (or running). and 1c turns on the ecu while cranking?

would 1b drop to 0v while cranking?

 

Everything to do with the ECU is low current, but most of it probably comes from the main relay since it's purpose is to provide power to the whole EFI system. The battery connection is just to keep the ECU's memory. I'm not sure about the ignition one, since it's the ignition key that activates the main relay. I've only got an S4 wiring diagram, and that shows only the main relay and the battery powering the ECU.

 

3I would be a good place to look for a place to tie in a theft protection device. On a series four anyway. It gets its power from the EGI COMP fuse. That's a 30a fuse....but that's because it feeds all those solenoids on the rack and acv. It's feed to pin 3I on the ECU isn't pulling anything close to 30a. If I ever receive the current clamp I ordered two weeks ago, I'll be able to tell you how much current it draws. This answer is addressed to a pm I received a while back about theft protection. ICEMARK would be a good contact for theft devices and where to tap.

EDIT: I just looked at page50-25 of the 88 online wiring diagram and it also shows pin 3I. No power to 3I.....no starty car. Its the same as having pulled the EGI COMP fuse. This should answer your pm.

 

ya the S5 is a bit different.

your 31 is my 1B. but I also have the addition of 1C







my concern is with 1b cut. would the ecu still power while cranking through 1c? and they suddenly shut off when it stoped cranking and went back to "ON"? or would b make the ecu still never turn on.

cutting b seems it wouldn't allow it to run. but I just don't want it doing harm etc if the ecu can try to start and then sudden power on / off.

I just wana make sure I'm not gona damage the ecu while either 1: cutting 1b while the engine is running (just incase). or 2: trying to start car with 1b cut

I'm gona asume the current is probbaly pretty low.

PS hailers I was hoping to keep some of that convo private