legacycentral bbs

Ok guys, need some help. I have a complete harness that I have stripped down to the essentials for the engine. I am putting the engine into a Brat. I have a painless fuse box that I will use for supplemental power but I need direction. Here is a list of the wires I have questions about what to do.

Plug B48, pin 15: Back up power supply
Is this basically power all the time? Fused of course right?

Plug B58, pin 9: AT Control unit, parking switch
I am using a 5 speed, what do I do with this???

Plug B58, pin 11, VSS
this goes to the dash, but I am going to use a GPS speedo to make sure speed is correct. What do I do with it??? if not using it???

Plug B56, pin 9, I have mixed info on this. Some say no connection, but I have a wire from the ECU. What is it and where or what do I do with it?????

Plug B56, pin 10, starter switch right???? What do I do here? Fused right????

Plug F47, pin 17, 22, this is AC stuff that I don't have. Do I just safe them off????

I have auto CC unit, can I use with a 5 speed? How to do that??? Thanks guys

Yes, backup power supply is fused power all the time.

You can leave the parking switch pin disconnected. Just make sure that you wire the transmission ID pin correctly (I can't remember for sure, but I think you just have to leave that pin disconnected too).

The ECU will not function well without a vehicle speed sensor signal. On the Legacy, the VSS is built into the speedometer (a cable drives the speedometer, and the speedometer outputs the electrical signal). I don't know what you should do about this with your BRAT. Later-model Subarus use electronic VSSes that screw into the transmission exactly the same way as the speedometer cable does; it's possible one of those would screw into your BRAT's stock transmission too. Then you could just connect that directly to the ECU.

Otherwise, you'll need to rig something up. Here's what VW guys have come up with.

B56 pin 9 is the A/C switch. On the Legacy, the air conditioning switch is connected to the ECU, and the ECU is in charge of engaging the compressor clutch by activating the relay connected to F47 pin 22. Since you have no A/C, just don't wire either of those pins to anything.

F47 pin 17 is for the radiator fan. You need some way to control the electric radiator fan. One way is to use this pin -- connect it to the ground side of a relay that is used to power the fan. Then the ECU will turn the fan on whenever coolant temperature is high and vehicle speed is low. Your alternatives include an independent thermostat or even just wiring the fan to run all the time.

The starter switch wire should be wired to the starter circuit of the ignition switch. You can fuse it if you like; it's not fused in stock form. This just tells the ECU that you're trying to start the engine so it knows to use base timing and dwell and such; the engine will usually start fine without this wire but it's helpful to make sure.

I believe some board members have used their stock AT cruise control computers after 5MT swaps with a little bit of rewiring. I'm sure you can find the details with some searching. You will, of course, need a VSS for this.