[PHATsuby]

Hopefully CambridgeRS can confirm this info and I will fully disclose that I have a 2009 STi swap for sale in case people think I'm biased but I too think it is doable and there is a lot of misunderstanding.

The CANbus system is simply how some things communicate. The engine and all the sensors are still fully wired in directly to the ECU. If you have the immobilizer stuff all wired up correctly so that the car will start you can run the car. If you are missing certain components you will put the car into limp mode.

The fact that the HVAC/radio system and cluster are on CANbus does not mean they are necessary to have the car to run.

If I understand this correctly and I'm fairly certain I do(cambridge can hopefully comment). The cluster uses the CANbus to get information on the sensors, so even though the fuel level sensor sends voltage to the ecu directly, the ecu will send that info out to the cluster via the body integrated unit(it MAY be directly from the ecu but either way still uses CANbus for this).

The ABS sensors send their signal to the ABS control module, which in turn sends the signal(I believe an average of the 4 wheel speeds) to the body integrated unit which then generates a VSS and sends it to the ECU and the gauge cluster.

My thoughts are that even though subaru changed the ABS trigger to a magnetic ring, they likely left the same amount of polar changes or "teeth" as the older mechanical ones so they didn't have to reprogram all their VDC info. That is speculation but potentially reasonable. If the teeth are the same, they are still hall effect sensors and the waveform would be the same meaning you could wire the old abs directly to the ABS control unit. Or if you are not using the VDC, you could just wire your mechanical VSS sensor into the appropriate wiring for your gauge to pick it up.

The things I am not clear on is exactly how the VDC works and if it is necessary to have the ecu not in limp mode. My plan was to only sell the engine with the wiring harness but keep the transmission and DCCD components if possible. From what I have read it says if there is an issue with ABS it will go to a default mode so ABS is retained. That makes me think the car will still function just fine with VDC components missing it will just be unable to use the VDC.

If any of that info is incorrect feel free to correct me. I have a nearly complete 2010 STi wiring diagram but am missing a couple sections I didn't realize till later that could answer some more questions. I seriously think this swap is doable especially if you have the harness and the components to keep the ecu out of limp mode.

Ben

 

[PHATsuby]

Not trying to sound cocky......but......Yes....yes I do......


When I did my '07 WRX engine in 2008 I was told it wouldn't work either....those people were wrong........

If you're good at wiring, this job isn't that difficult, just tedious.

Also, didn't CANbus start in 08+ on the wrx's and 2007+ on the legacies? This is what I was told but I thought CANbus was used in the 2005 legacy cars, but was told I was incorrect.

Just wondering if you are 100% certain your engine is CANbus.

Thanks

Ben

 

[Brydon]

The CANbus system is simply how some things communicate.

It is shared information between different parts of the car to eliminate seperate systems and save money

The engine and all the sensors are still fully wired in directly to the ECU.

The is completely false! Some are but a lot are eliminated and then transfered via CAN. That is the point of CAN.

If you have the immobilizer stuff all wired up correctly so that the car will start you can run the car.

This is also false! The immobilizer and security are one. So I assume you have to rewire all the security into the swapped car.

If you are missing certain components you will put the car into limp mode.

This is very true. That is the problem. Limp mode will not run correctly, will turn off parts of the internal ecu maps, and wont let you rev over 4k or boost. So it depends on how you feel about running. It will get you to the store but not to the track. Or get you on the freeway safely.

The fact that the HVAC/radio system and cluster are on CANbus does not mean they are necessary to have the car to run.

True and it will probably run ok. But how do you feel about overheating? I don't like it but you might be okay with it. The ecu operates the fans so if you can get the AC to turn on which it probably wont with out the CAN for the HVAC working correctly. Then the fans wont turn on. I consider this important but that is me. I like AC.

The ABS sensors send their signal to the ABS control module, which in turn sends the signal(I believe an average of the 4 wheel speeds) to the body integrated unit which then generates a VSS and sends it to the ECU and the gauge cluster.

True so you need the newer ABS or you get no VSS which means limp mode which means shitty car.

My thoughts are that even though subaru changed the ABS trigger to a magnetic ring, they likely left the same amount of polar changes or "teeth" as the older mechanical ones so they didn't have to reprogram all their VDC info. That is speculation but potentially reasonable. If the teeth are the same, they are still hall effect sensors and the waveform would be the same meaning you could wire the old abs directly to the ABS control unit. Or if you are not using the VDC, you could just wire your mechanical VSS sensor into the appropriate wiring for your gauge to pick it up.

I'm pretty sure you are right that the sensors are the same but that doesn't change the fact that you need the new ABS so you will have to splice.

I'm fairly sure I could make this swap work but it doesn't change that it will be a lot of work. I 07 STI swap takes one day for me to do the merge and the motor. A 08 I would not do for anyone short of myself. It would be a great swap when it was done but I would spend a lot of time making everything work correctly. You would for sure need the entire car at disposal to make sure this goes correctly. And no one does this because there are much cheaper options.

 

[CambridgeRS]

Also, didn't CANbus start in 08+ on the wrx's and 2007+ on the legacies? This is what I was told but I thought CANbus was used in the 2005 legacy cars, but was told I was incorrect.

Just wondering if you are 100% certain your engine is CANbus.

Thanks

Ben

Hey Ben

You are absolutely right my '07 WRX engine is NOT CANbus. I was kinda checking to see if anyone was paying attention. I guess anyone else who caught it just thought I was an idiot....:rolleyes4.....don't blame them I guess. I'd probably ignore me too!:blol:

When I started researching the '07 swap, several people on various forums swore this engine was CANbus and I would have the same issues we are talking about now!

This is just speculation, but I would think that if the cluster, HVAC, Audio, or NAV systems are disconnected that this would NOT put the car into 'limp mode'. Why would they? No part of the car would be at risk of damage (including the driver) if these did not operate properly or at all.

I think the idea behind 'limp mode' is to reduce the risk of damage to the engine, tranny, etc, due to faulty sensors or modules. I guess as a secondary, it keeps you from being stranded when something goes wrong.


Jeff

 

[CambridgeRS]

The is completely false! Some are but a lot are eliminated and then transfered via CAN. That is the point of CAN.

Agreed! Signals from each system (engine,DCCD, ABS/VDC,etc) are passed to all other systems over the CAN network. The other systems 'choose' whether to use that information or not.

This is also false! The immobilizer and security are one. So I assume you have to rewire all the security into the swapped car.

Agreed, but I think what PHATsuby was getting at is that the Immoblizer and ECU have to match(from the same car) to make the swap work cleanly. Otherwise, it's a trip to the dealer to have them reprogram the ECU to work with the installed Immobilizer if you can find one that will do this for you.

True and it will probably run ok. But how do you feel about overheating? I don't like it but you might be okay with it. The ecu operates the fans so if you can get the AC to turn on which it probably wont with out the CAN for the HVAC working correctly. Then the fans wont turn on. I consider this important but that is me. I like AC.

Wait a second....this will depend on what car this is being swapped into.
If it's a GC (or I think a GD) the A/C system is pretty much a stand alone system. This means that the original HVAC system should operate without problems. What might be missing is an 'idle up' signal to the ECU when the blower fan turns on. This signal will cause the ECU to increase idle speed when the electrical system is under greater load. This is not a major issue to me because you don't really sit around at idle for long periods of time though you might notice having to rev the car a wee bit earlier when taking off from the lights. I usually rev mine alot earlier....lol.....

I'm fairly sure I could make this swap work but it doesn't change that it will be a lot of work. I 07 STI swap takes one day for me to do the merge and the motor. A 08 I would not do for anyone short of myself. It would be a great swap when it was done but I would spend a lot of time making everything work correctly. You would for sure need the entire car at disposal to make sure this goes correctly. And no one does this because there are much cheaper options.

Amen to that! Definitely a big job, but the more I research the more I want to do it! I think the gratification of completion justifies the means!

Jeff

 

[BRP_GM6]

I am glad this thread is getting some attention, and is getting some good discussion. As for the amount of time it takes to rewire all of the systems, remember that even the guys that we consider guru's today, used to take a month on a WRX swap. Anything is posible, guys.
Something to think about:
It seems to me that the BIU is the most likely piece that is central to the CANbus system. What evidence is there that the ECU requires the BIU to run correctly?

 

[seraphinwolf187]

May I present another thing to think of?

On the LGT end of these the ECU can't be open sourced. While the 08' STi can it's just a point to bring up. For some models that is.

 

[Brydon]

Wait a second....this will depend on what car this is being swapped into.
If it's a GC (or I think a GD) the A/C system is pretty much a stand alone system. This means that the original HVAC system should operate without problems. What might be missing is an 'idle up' signal to the ECU when the blower fan turns on. This signal will cause the ECU to increase idle speed when the electrical system is under greater load. This is not a major issue to me because you don't really sit around at idle for long periods of time though you might notice having to rev the car a wee bit earlier when taking off from the lights. I usually rev mine alot earlier....lol.....

This is not true! Even on the GC the AC is operated by the ECU. You hit the button on your HVAC and that goes directly to the ECU which turns on the AC relay. The ECU actually controls it all. Including the Relay, both fans, and power to the thermoswitch. The only thing that is stand alone is the pressure switch that will cut power to the AC to turn it off if the system over pressurizes.

I haven't looked at all the CANBUS on newer vehicles but the LGT was twisted pair for all of the HVAC signal so the ECU. So the GC or GD would simply not have the ability to tell the ecu to turn on the AC. Although if you don't want AC then I suppose that is an option. Personally I AC. It also activates the blower switch which adds a little fuel to the map. It would likely run fine without all of this. And come to think of it I bet the small light and defrost are also on CAN.

For this area I would say the best option is straight swapping the entire HVAC system from the CAN car. The CAN cars all use climate control that have soleniods to operate vents, in/outside air and heating. The GC uses cables for all of these.

All of this is not really the biggest hurdle I see. The speed sensor and immobilizer security are much bigger. Both of which NEED to be swapped. The security involves door locks/immobilizer/key/antenna/keyless/and shock sensors(If the cars have them. Also haven't looked at that.) In the CAN cars this is all one unit instead of separate ones like the 05-07 STIs and 06-07 WRX. The ABS would need the newer ABS unit but I would guess the sensors are still the same. I'm almost positive of this because the LGTs are the same as older imprezas. At least for rings on the axles tooth pattern. If that makes sense.

On top of all the stuff that the ecu needs to operate correctly your car also needs some things to operate correctly. You need to add and wire the old speed sensor to the new tranny to make your speedo work. You need to add and wire the gauge sensor for the coolant temp. The CAN cars get this from the ECU and that sensor is not that same sensor as the gauge so you cannot just piggyback the gauge wire to it. The oil pressure dummy is still there so that is not a big deal. However the tach will be a giant problem. Aftermarket would probably be the best option because the tach signal comes from the old ecu on all older 93-07 imprezas. This is a 5v signal that can not be taken from the ignitor like most aftermarket tachs. Again CAN gives this information to the gauge cluster and the GC/GD does not have CAN.

 

[Brydon]

It seems to me that the BIU is the most likely piece that is central to the CANbus system. What evidence is there that the ECU requires the BIU to run correctly?

Without the body integrated unit the car will never start. Again on older cars this is seperate but on the CAN cars the immobilizer is all part of this system. No immobilizer No run.

 

[CambridgeRS]

This is not true! Even on the GC the AC is operated by the ECU. You hit the button on your HVAC and that goes directly to the ECU which turns on the AC relay. The ECU actually controls it all. Including the Relay, both fans, and power to the thermoswitch. The only thing that is stand alone is the pressure switch that will cut power to the AC to turn it off if the system over pressurizes.

Brydon

I apologize....I was wrong about the A/C. I must have been thinking about my old Corolla. Anyway, there may still be a way to bypass the ECU on the older systems and I have an idea about how to do this, but I'd have to try it. Unfortunately, the A/C wasn't charged when I got my car, and I never did bothered to get it done, so recently removed it. That makes testing this a bit difficult.

This is a 5v signal that can not be taken from the ignitor like most aftermarket tachs. Again CAN gives this information to the gauge cluster and the GC/GD does not have CAN.

I'd like to try merging GC cluster and a GR cluster. I know this sounds dumb, but if it works, it would be a pretty awesome mod!

Like I said before.....if anyone has a GR cluster, working or not, I'd buy it just to tear it apart to see if it is possible.

 

[CambridgeRS]

Without the body integrated unit the car will never start. Again on older cars this is seperate but on the CAN cars the immobilizer is all part of this system. No immobilizer No run.

Reading in the manual, it looks like the BIU is registered to all CAN units. If it is changed or replaced, the BIU defaults to a a factory setting and operating the vehicle is impossible. A Subaru Select Monitor is required to re-register the BIU to the system.


Also, another point to mention is that the ECU and the ABS(or VDC) must be connected to the CAN network or operating the vehicle will be impossible. Each of these units have terminating resistors built in to stabilize communication across the CAN_Hi and CAN_Low lines.

A full description of the CANbus can be found in theTechnical Services Bulletins manual. If anyone would like a copy of this manual, PM me and I'll email it to you!

Jeff

 

[PHATsuby]

The is completely false! Some are but a lot are eliminated and then transfered via CAN. That is the point of CAN.

My statement is not "completely false" it is actually completely true. It may have been misread.
Re-read what I wrote. I said all the engine and all the sensors are directly wired to the ecu. This should be read as the engine's sensors are all directly wired. If you can tell me a sensor that is on the engine that does not go directly into the ecu harness then I will consider my statement inaccurate. I was not stating that ALL sensors on the entire car are directly wired to the ECU.

In regards to the Fans not turning on, you do realize there are direct radiator fan relay wires off the ecu right? and if it gets too hot it will turn these on. It would be a matter of wiring these up directly if you think that goes through the CAN HVAC system. There is no need for sarcastic remarks I'm simply trying to solve the issues.

This is also false! The immobilizer and security are one. So I assume you have to rewire all the security into the swapped car.

Cambridge is correct I was saying if you have matching immobilizer components to avoid the engine not starting for security reasons you should be able to start it.

True so you need the newer ABS or you get no VSS which means limp mode which means shitty car.



I'm pretty sure you are right that the sensors are the same but that doesn't change the fact that you need the new ABS so you will have to splice.

I'm not sure if you are agreeing or disagreeing with me, I know no VSS means limp mode, hence why I speculated about using an actual mechanical speedo sensor and wiring that up to the ECU to avoid limp mode if you have the older ABS and tranny with a speedo sensor.

If you are trying to do this swap without having to splice any wires, good luck. That is not what I am saying is possible, I am saying there are potential solutions to give the ECU what it is looking for without using every single component on the car in the new car.

Ben

 

[PHATsuby]

Reading in the manual, it looks like the BIU is registered to all CAN units. If it is changed or replaced, the BIU defaults to a a factory setting and operating the vehicle is impossible. A Subaru Select Monitor is required to re-register the BIU to the system.


Also, another point to mention is that the ECU and the ABS(or VDC) must be connected to the CAN network or operating the vehicle will be impossible. Each of these units have terminating resistors built in to stabilize communication across the CAN_Hi and CAN_Low lines.

A full description of the CANbus can be found in theTechnical Services Bulletins manual. If anyone would like a copy of this manual, PM me and I'll email it to you!

Jeff

Do you have the name of the file? I may have it already and I would like to read what it says. Is it the mechanism and function section PDF?

Thanks

Ben

 

[CambridgeRS]

Do you have the name of the file? I may have it already and I would like to read what it says. Is it the mechanism and function section PDF?

ThanksBen

I have a downloaded version from a friend, so I'm not sure if this is the correct name, but you can find it in the 'Technical Service Bulletins' folder.

Mine is called 'Technical Service Bulletins.pdf'. I know this doesn't follow Subaru's earlier naming convetion(eg MSA5T0614A151939.pdf).

In the PDF, you need to look at....

Section C Mechanism and Function(All 2008 models)

Sub section...

05. Electrical

Sub section.....

E. LAN System



Jeff

 

[PHATsuby]

Thanks Cambridge, it looks like I had it.

In reading that PDF again, I think if you read it again it says that if one of the components is missing it can no longer communicate on that system but the communication between other units remains in tact. It is definitely confusing on how it is worded.

Maybe I am thinking of it optimistically but I am fairly certain that is what it says. The lines are run in parallel so it would make sense that if one unit is missing, all the others would still be able to communicate. The resistors built in stabilize the communication on each unit, if one is removed it doesn't make all the communication impossible.

In my situation I have the ECU, the full body harness and engine harness, the BIU and all the immobilizer components and the cluster. The ABS unit I think is damaged(outside of it was cracked). I have the whole car and all the DCCD components but obviously I want the tranny and DCCD parts for myself since no one will want to spend 10k on the full drivetrain.

If the ABS unit was replaced that would solve that issue but I want to determine if the older ABS sensors can be used in its place so its not a matter of needing the new hubs and suspension.

Ben

 

[CambridgeRS]

Thanks Cambridge, it looks like I had it.

In reading that PDF again, I think if you read it again it says that if one of the components is missing it can no longer communicate on that system but the communication between other units remains in tact.

The lines are run in parallel so it would make sense that if one unit is missing, all the others would still be able to communicate. The resistors built in stabilize the communication on each unit, if one is removed it doesn't make all the communication impossible.

This is true and not all at the same time...lol!

The ECU and the ABS/VDC are the only units with terminating resistors which make them required in the system. Take a closer look at the pic below. #1 and 3 are the ECU and ABS respectively. #10 is the terminating resistor. There is one in the ECU, and one in the ABS.

#5 also shows a terminating resistor but that's the VDC. If you have VDC, you don't have ABS. In other words the ABS and VDC replace each other depending on what your vehicle is equipped with.

Having said that, all other modules that are shown on the network can be removed and still maintain communication on the main(trunk) line.

Think of this network like a tree. The ECU and ABS/VDC make up the trunk and all other modules are branches. If you remove a branch, life goes on with minor effect. If you sever the trunk, the tree dies.

I have the whole car and all the DCCD components but obviously I want the tranny and DCCD parts for myself since no one will want to spend 10k on the full drivetrain.

Ben

I think you'll have problems with the DCCD as well! It too is on CANbus. If you don't have the CANbus, the DCCD won't get information from the YAW sensor and Steering Angle sensor which are also on the CANbus.

If you're just looking to to the transmission you may be better off to find a pre 2008 that doesn't have CAN and go with an aftermarket DCCD controller. For that matter, you could probably use and aftermarket controller on the 2008 tranny also. We'd have to compare the '08 tranny wiring to the pre '08 stuff.

I'm currently looking for a whole 2008 STi for a swap, so if you're interested in selling your's, send me what you'd like to get for it(maybe a couple of pics too)!


Jeff

 

[PHATsuby]

Yea, you are right, looking at it that makes sense.

My original plan was to make a 2011 STi Legacy GT so the 2009 Tranny was going to be fine to use. Depending on what I had to sell for the engine to work I was potentially going to try and make a fully functional DCCD setup with Si Drive but that was only if I was selling the motor without all the wiring and ECU.

I'll PM you as well.

Thanks.

Ben

 

[Brydon]

I'm glad this thread went in a positive direction. I still really think that the 08 STI is still priced outside of what I would spend on a GC and with the amount of work to make this happen correctly you almost have to do it yourself or you could own a 08 STI outright.

 

[PHATsuby]

I'm glad this thread went in a positive direction. I still really think that the 08 STI is still priced outside of what I would spend on a GC and with the amount of work to make this happen correctly you almost have to do it yourself or you could own a 08 STI outright.

While you are entitled to your opinion and this may be true to most people I think we should keep this about CANbus technical information and not what people think is a viable swap option. Many people out there do their own work, myself included. Plus I'd like to learn as much as possible as it is always a challenge.

The more info we can figure out and the more problems we can solve the easier this swap will be/become in the future.

Ben

 

[PHATsuby]

I think we should potentially re-cap what we have concluded and then try and move on to solve issues we don't have answers to.

IMO I think there are a lot of potential options that could make this easier if we can figure them out.

One thing we know is the ECU and ABS Module have to be connected and that the ECU needs the VSS to stay out of limp mode. This says nothing of the possibility that the GC(or older mechanical teeth) ABS sensors can be used, other than the fact we know it needs ABS input. One potential solution to this would be to count how many teeth are on the current GC and then count the polar changes on the new hub(I will volunteer to do this if I can decide on a reliable way to measure). IF the teeth/changes are equal it is likely that the waveform output is the same and would be useable for the input into the ABS Module.

Another way to simplify this if someone just wanted to run an older 6MT with a DCCD controller, would be the possibility of using an ABS control module without VDC so that it does not need the yaw sensor and other VDC components.

Additionally, there may be an option to simply just have a 6mt with a speedo sensor feed the ecu the signal it needs but we would have to verify the waveform is the same. The ecu just wants to see a correct speed signal, it does not care where it comes from in theory. This would be unnecessary if we can in fact wire in the older ABS sensors but if we can't we may be able to just get the ABS module and have it hooked up so CANbus HI will work and feed the VSS signal directly.

I will try and check the hub ring in a couple weeks when I can get to the car again unless someone has access in the mean time.

there is an ABS diagnostic pdf that may tell us the answer if we compare the new to the old, but that would not be direct verification.

Ben