Converting automatic donor to standard transmission

[65 Cobra Dude]

Hello All,

Many remember I bought an automatic 04 WRX for my donor and was planning on figuring out how to get the auto to work in the 818. Others are getting that to work but I abandoned it because of the length of the tranny and issues getting it to work. Because of this, I decided to convert my auto to a standard. Automatic donors are much more plentiful and cheaper to buy and the conversion is not as bad as I thought. Parts you will need:

tranny/diff
full clutch (including fork)
flywheel and bolts
starter
slave cylinder and bracket/spring
pedal box
clutch master cylinder
tranny mount (auto is different than standard)
inner CV joints
all bolts, nuts and washers

I bought all this from a salvage yard for $800 complete. It came with clutch assembly but I decided to buy a new clutch, throw out, pressure plate and pilot bearing before assembling.

The wiring is what made me most nervous. There is plenty of information on the web but you need to weed through it to get accurate information. There are 3 circuits that need to be changed - vehicle speed sensor (VSS), neutral safety switch (NSS) and reverse lights.

For the VSS, the tranny has a 3 wire VSS (signal, gnd and power) whereas the auto had 2 wires. I am in the process of running 3 new wires to the VSS and the signal one connects to either the computer or speedo but must be connected to both. I am just tapping into the wire at the computer (I'll document pin number/wire color in next post).

For the NSS, I want to use that as a clutch safety switch where the clutch must be depressed before car will start. Pretty sure this should be fairly easy as well by fooling the auto computer that the car is in park or neutral when the clutch is depressed. Also need to take into account the 2 wires at the auto shifter. They need to be connected together so key will come out of ignition and fuel pump has power.

Reverse lights should be the simplest. More on that once I have them wired.

More to come,

Henry

[Erik W. Treves]

Henry, you need to fool the computer into think it's in D for it to go into closed loop...so N when the clutch is in and D when it's out. I too went through this exercise and did a ton of research...there is a lot of confusing data out there and hopefully this is not adding to it...lol...

here was mine..before I dumped it go stand alone from Wayne

CLutch in for start:



OUt to go for a drive: --- this was to D not N.

[ssssly]

Why not just get a harness and ECU?

[Jaime]

I have an auto-converted-to-manual that I already go karted. All I had to do was ground one pin on the ECU to put it in manual mode and re-wired the three circuits mentioned above.

[ssssly]

Depends on the ecu. That will work for the newer ones but not the older ones. Not sure which ECU the op has.

[Louisromersh]

I have an auto-converted-to-manual that I already go karted. All I had to do was ground one pin on the ECU to put it in manual mode and re-wired the three circuits mentioned above.

Hi Jaime,

How did you add the clutch pedal to your build?

[Jaime]

I bought a clutch-brake assembly from eBay. The wiring harness doesn't have the connectors for it, so I had to improvise a bit. The clutch sensor goes to the starter interlock, I wired the it in place of the park switch that the automatics have.

[Louisromersh]

OK I'm not going to lie this topic is very intriguing because there is a donor cars out there that are much cheaper because of there automatic transmission and it seams 4EAT 818 sounds very confusing.

So please keep this thread updated so I have a better idea of the steps need to be done to make this conversion.

Thanks

[Bob_n_Cincy]

Louisromersh
My donor was a 04 forester xt (turbo) with an automatic ($2800)
I had a second donor 06 impreza NA bad engine ($400)

I used engine, wiring harness and ecu out of the forester.
I used the transmission and pedal box out of the impreza.

I removed the TCU and a few other manual specific wiring changes.

The car ran and drove like this with some CEL codes related to the missing TCM. My tuner loaded software for 04 manual forester and all is perfect now.

Hope this helps
Bob

[Jaime]

I bought an '05 automatic WRX sedan for $1000 - but it needed a radiator and lower control arms due to a front end accident. I picked up a 5-speed, clutch, flywheel, throwout, clutch slave, sensors, transmission wiring harness, and axles for $700. So that comes out to about $2300. No way I could have picked up an equivalent 5 speed for that little.

I removed the TCU and grounded pin C1 on the ECU and got no CELs.

In an auto, the starter interlock is part of the shifter mechanism, so it won't start without it. Run ignition power through a relay to the starter - power the relay coil via the clutch switch to create a new safety interlock circuit and it will start again.

The wires for the speedo sensor come from the TCU on the automatic. Make sure you don't cut them when removing the TCU and tie the speedo sensor from the 5 speed to the Green/Yellow wire.

Run the neutral switch to pin A8 on the ECU (ground on the other pin of the neutral switch).

I looked at the 2004 wiring diagram and it looks like the exact same strategy will work. 2001/2002 use pin E1 to switch to MT mode, but everything else looks the same.

[Louisromersh]

OK Gents,

I understand the mechanical aspect of the conversion. Now for the electrical I'm a little lost is it possible to for you guys to share the wiring diagrams for a automatic & manual transmission so I can see what you guy's are referencing.

Also Bob_n_Cincy I like your methodology of mix and match but all the WRX and Foresters are expensive here in CO the cheapest WRX with automatic is the one I'm looking to buy is $4000 and it has a spun bearing and/or rod knock so the
engine needs to be rebuilt.

2004 WRX with Rod Knock.JPG

Thanks
Gents

[Jaime]

Here's the easy one:



Tie C1 in to the same ground that A7 and A15 are tied to. C1 won't have a pin, but after you remove the TCU, you'll have a bunch of unused pins you can move to C1.

[Jaime]

The speedo sensor wiring looks like this:



Just tie pin 1 of the MT speedo sensor into the GY wire that was connected to the TCU.

[Jaime]

The starter interlock takes more work:



You'll need a relay. The coil of the relay is activated by the clutch switch and the load side of the relay wires in where the AT shift mechanism was.

[Jaime]

The neutral switch will have to be wired like this:



Notice that's the same A8 that was marked "AT" in the starter interlock circuit - so it will already have a wire to the ECU connector, but it will need to be re-routed.

[Bob_n_Cincy]

Also Bob_n_Cincy I like your methodology of mix and match but all the WRX and Foresters are expensive here in CO the cheapest WRX with automatic is the one I'm looking to buy is $4000 and it has a spun bearing and/or rod knock so the
engine needs to be rebuilt.

Louis
Have you looked at salvage cars for coparts or other auctions?
I got both my cars that way.
Just to clear something up, I needed 2 sets of suspension, brakes, steering as I have 2 818s.

Jamie did a good job covering the electrical difference above.
Bob

[Louisromersh]

Louis
Have you looked at salvage cars for coparts or other auctions?
I got both my cars that way.
Just to clear something up, I needed 2 sets of suspension, brakes, steering as I have 2 818s.

Jamie did a good job covering the electrical difference above.
Bob

Hi Bob,

Yes I have look and I do keep a eye out threw Autobidmaster, but since I have never tore down a car or rebuilt a car before in my life I would like to stick with the idea if I pulled it out and it was in a
running conduction it should go back in and run. So with the car that I last posted my idea would to try rebuilding the motor and put back in the car get it running then either sell the car for a car with a manual trans or
use it as my donor and convert it.

Also I have been watching the auto auctions web site and on average once i win a auction plus fees and shipping I'm in range of buying a car off of Craigslist in my option.

Thanks

[Louisromersh]

The neutral switch will have to be wired like this:



Notice that's the same A8 that was marked "AT" in the starter interlock circuit - so it will already have a wire to the ECU connector, but it will need to be re-routed.

Jaime,

This one I'm little lost on do I wire this inline or in series with the starter interlock?

Thanks
Louis

[Bob_n_Cincy]

Jaime,

This one I'm little lost on do I wire this inline or in series with the starter interlock?

Thanks
Louis

I'll get this question for Jaime,
The neutral switch only goes to the ECU. The car will start both in and out of gear.
The clutch switch (and starter interlock relay) go into the start circuit. It must be depressed for the starter to run.
Bob

[Louisromersh]

I'll get this question for Jaime,
The neutral switch only goes to the ECU. The car will start both in and out of gear.
The clutch switch (and starter interlock relay) go into the start circuit. It must be depressed for the starter to run.
Bob

Bob,

What's got me confused then is both schematics have them going to pin A8 on the ECM so then do they get wired in parrallel, series, and/or are there to A8 Pins?

Louis

[Bob_n_Cincy]

Bob,

What's got me confused then is both schematics have them going to pin A8 on the ECM so then do they get wired in parrallel, series, and/or are there to A8 Pins?

Louis

I marked up a schematic. You have to remove any wires with "AT" arrow and add any wires with "MT" arrow.
Does this clear it up for you?
Bob

[Louisromersh]

I marked up a schematic. You have to remove any wires with "AT" arrow and add any wires with "MT" arrow.
Does this clear it up for you?
Bob

Yes Bob,

That does clear it up! Now that you did that I feel like Gibbs just head slapped me on the back of the head.

Louis

[Louisromersh]

OK Gents,

Just for other and my knowledge would all these changes be the same if I were to convert to 6MT?

Thanks