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Thread Tools Display Modes
  #61  
Old 05-28-2007, 09:02 AM
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Wink with apologies to the non-geeks...

Quote:
Originally Posted by svxistentialist
Your breaking down of the software inside the TCU may well lead to better or less complicated permanent switching, which would be great!
That's the plan.
Quote:
Originally Posted by svxistentialist
If you think the OZ WSM for the gearbox might be useful, I'd be happy to post it to you, and collect at JAE.
Thanks for the offer. I'll let you know if I need it.
Quote:
Originally Posted by svxistentialist
As regards your point above with the timer, the complication could be the speed signal, as Power mode shift map is put in place by two variables, throttle position and road speed. The following is how the WSM describes the drop back to Normal:

The power pattern is shifted to the normal pattern depending on car speed. Shifting to the normal pattern is determined by the throttle position as shown in the figure on the right. Time lag in shifting [from power tonormal] is also determined by car speed. The maximum time lag is 3 seconds.

The diagram is a simple Venn diagram. Judging by the relative areas shown it would be reasonable to presume that Power will drop off [on cutting back throttle opening] after 3 seconds at lower speeds, after 2 seconds at mid speeds, and after 1 second at high speeds. I expect low, mid and high speeds are preset atspecified ranges within the firmware.
That is exactly right. My US manual says the same word for word, and I found the code that implements it in the TCU firmware. I was planning not to post code here because it's a bit too nerdy for a car forum . But in this case I think it's relevant and it gives a taste of what I'm working with.
Code:
e796 ce c9 04   ldx 0xC904             // Vehicle speed table for power to normal switching
e799 96 18      ldaa (0x0018)          // Vehicle Speed (don't know how to convert to mph)
e79b 5f         clrb                   // b=0
e79c a1 00      cmpa (X+0x00)          // Compare speed to first entry in table (1E)
e79e 23 0b      bls [0xE7AB]           // if speed <= 1E goto  e7ab
e7a0 5c         incb                   // b=b+1
e7a1 a1 01      cmpa (X+0x01)          // Compare speed to 2nd entry in table (3C)
e7a3 23 06      bls [0xE7AB]           // if speed <= 3C goto e7ab
e7a5 5c         incb                   // b=b+1
e7a6 a1 02      cmpa (X+0x02)          // Compare speed to 3rd entry in table (5A)
e7a8 23 01      bls [0xE7AB]           // if speed <= 5A goto e7ab
e7aa 5c         incb                   // b=b+1
The section of code above compares the vehicle speed against a table of values in the firmware. It calculates an index "b" which relates to the X axis on your diagram. b=0 for the first section is 0, 1 for the second, 2 for the third, 3 for the last.
Code:
e7af 58         aslb                   // b=b*2 (each item in the table is two bytes)
e7b0 ce c9 17   ldx 0xC917             // Throttle opening table
e7b3 3a         abx                    // add b to x (ie. add index to start of table)
e7b4 96 4c      ldaa (0x004C)          // Throttle opening
e7b6 a1 00      cmpa (X+0x00)          // compare to threshold from table (02,02,03,04)
e7b8 25 05      bcs [0xE7BF]           // if throttle < threshold goto e7bf
e7ba a6 01      ldaa (X+0x01)          // get timeout from table (4B,4B,32,19)
e7bc 97 c1      staa (0x00C1)          // Set power mode timer to timeout from table
e7be 39         rts                    // exit
The code above uses the index "b" calculated earlier to lookup a threshold and a timeout from a table of values in the firmware. This is the Y axis on your diagram. If the throttle opening is greater than the threshold, the timer is reset to the timeout value. Remember, this code is running several times a second, so the timer is constantly being reset. The timeout values correspond to 3 seconds, 3 seconds, 2 seconds, 1 second.
Code:
e7bf 5f          clrb                  // b=0
e7c0 96 c1       ldaa (0x00C1)         // power mode timer
e7c2 26 17       bne [0xE7DB]          // if timer >0 goto e7db
e7c4 d7 5a       stab (0x005A)         // set current map=b
e7c6 39          rts                   // exit
<snip>
e7db 5c          incb                  // b=b+1
e7dc d7 5a       stab (0x005A)         // set current map=b
e7de 39          rts                   // exit
The code above gets executed if the throttle is less than the threshold. If the timer has reached 0 then it sets the current map to 0 (normal) otherwise it sets it to 1 (power).
Quote:
Originally Posted by svxistentialist
This in turn leads me to believe that you may have more success holding power mode in the software by "fooling" it into seeing an open throttle all the time in the TCU software, rather than changing the timed drop-off interval.
The problem is that the raw inputs from the sensors like the TPS can't be overwritten. The variables that the TCU calculates from those sensors, can be overwritten. But it must be remembered that the TCU is constantly reading its sensors, recalculating these variables and overwriting whatever dodgy value I put in there with the correct one. Thats why frigging the timer is appealing, because it isn't calculated from any external source. All the TCU does is subtract 1 from whatever value is in there until it reaches 0.
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Last edited by b3lha; 05-28-2007 at 09:25 AM.
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  #62  
Old 05-28-2007, 09:16 AM
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That sounds good Phil. Keep us posted.

Your subroutine may work if you get it to iterate at faster than the 1/25 secs the calculations are made from.

I hope you get it to work, so you can re-programme my UK TCU at the JAE.. I'll buy you a pint and a vegetarian burger.



Joe
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  #63  
Old 05-28-2007, 09:49 AM
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Quote:
Originally Posted by svxistentialist
That sounds good Phil. Keep us posted.

Your subroutine may work if you get it to iterate at faster than the 1/25 secs the calculations are made from.

I hope you get it to work, so you can re-programme my UK TCU at the JAE.. I'll buy you a pint and a vegetarian burger.



Joe
<geek>
That's not my subroutine. That's the code in the TCU. I was trying to illustrate how it works.

Actually, if you think about it. I can set the timer to the maximum possible value of 255. That should give me 10 seconds before I have to worry about resetting it again.

There is no chance of being able to reset a variable every iteration. The protocol can only manage about 4 or 5 commands a second and it takes two commands to write a byte of data to memory.

At the moment, reprogramming is not on the cards. The only way this is going to work is to have a laptop in the car constantly sending data to the TCU to reset the timer.

</geek>
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Last edited by b3lha; 05-28-2007 at 09:52 AM.
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  #64  
Old 05-28-2007, 12:18 PM
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IT WORKS!

I just did a little road test. I can't (yet) make the power mode come on with software. But I CAN stop it from turning off. I setup my laptop to continuously reset the timer to 10 seconds. Then I gave the throttle a little tap to turn the power mode on....and it stayed on!

I drove around for 15 minutes or so with the power mode on then I stopped the laptop from sending the reset sequence. 10 seconds later, exactly as predicted, the timer ran out and the power mode turned off.



Of course, this is pointless on my JDM car, which has a power button anyway. But it might be a useful trick on Euro and USA cars. I think it's a better way than messing with the TPS signal which might be used for other things elsewhere in the TCU. The disadvantage is that you need a laptop in your car.

It is actually quite simple to do, once you know how:

Step 1: Send the command to read the value of the power mode timer ("4500C100')
Step 2: Send the command to write 255 to the power mode timer ("AA00C1FF")
Step 3: Goto step 1
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Last edited by b3lha; 05-28-2007 at 12:21 PM.
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  #65  
Old 05-28-2007, 12:23 PM
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Super!!

Now, stage 2. How do we impose this programme on the TCU without having a laptop in the cabin all the time.

Answers on a postcard.......

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  #66  
Old 05-28-2007, 12:48 PM
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Quote:
Originally Posted by b3lha
Of course, this is pointless on my JDM car, which has a power button anyway.
When I first read about your stuff on the POWER mode, this was the first thing which came to mind. What signal is sent when that switch is in the on or off position? Does it have some sort of override to the code you've been messing with up 'til now? Or is it sent to a separate part of the TCU entirely?

I'm just curious... wondering if duplicating the signal of the power switch on a USDM car would even work. I know we don't have a switch, but maybe we'll get lucky and our TCU will still accept the signal...

Hmm. Excellent work, though. It's been very cool watching you figure these things out. Hopefully we'll get EDM and USDM applications once you're done fiddling with your Japanese car, hahaha.
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  #67  
Old 05-28-2007, 01:13 PM
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code apologies once more.

Quote:
Originally Posted by Nomake Wan
When I first read about your stuff on the POWER mode, this was the first thing which came to mind. What signal is sent when that switch is in the on or off position? Does it have some sort of override to the code you've been messing with up 'til now? Or is it sent to a separate part of the TCU entirely?

I'm just curious... wondering if duplicating the signal of the power switch on a USDM car would even work. I know we don't have a switch, but maybe we'll get lucky and our TCU will still accept the signal...

Hmm. Excellent work, though. It's been very cool watching you figure these things out. Hopefully we'll get EDM and USDM applications once you're done fiddling with your Japanese car, hahaha.
The power switch on JDM models connects pin a4 of the TCU to ground. That's pin 4 of the 20 pin connector known as B66 on the diagram. On UK cars, this pin is used for the Economy switch. The pin is present on USDM cars but there is no switch connected to it.

When you push the power button, bit 6 of memory location 0011 in the TCU changes from 0 to 1. That's all, everything else is done in software. The software handles it like this:
Code:
e77f 13 11 40 04 brclr (0x0011), 0x40, [0xE787] // if powerswitch=0 goto e787
e783 c6 02       ldab 0x02                      // set b=2
e785 20 55       bra [0xE7DC]                   // goto e7dc
<snip>
e7dc d7 5a       stab (0x005A)                  // set current map=b
e7de 39          rts                            // exit
The first line checks bit 6 of location 0011. Remember, this signifies whether the power button is on. If the bit is 0 then it goes to e787 and does the normal processing described earlier. Otherwise it sets the current map variable to 2 and exits from the subroutine.

This current map variable at location 005A governs which shift map is used. If it is greater than 0 then the TCU will use the power shift map instead of the normal shift map.

IF the USDM TCU contains the above lines of code (it might well do) then connecting a switch to pin a4 of the TCU will allow you to switch power mode on and off just like a JDM model. Otherwise, you're stuck with the timer frig method that I just invented or the TPS trick from Terry McLane's original SVX FAQ. The only way to know for sure is for somebody either to wire up a switch and try it, or download the code from a USDM TCU so I can have a look at it. Once I've progressed things a bit further, I'll try and get my hands on a USDM TCU.
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Last edited by b3lha; 05-28-2007 at 05:49 PM.
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  #68  
Old 05-28-2007, 01:23 PM
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It's hilarious; I can keep up with the code jargon but when it comes to the details on the car I totally falter. Which pin is A4? I'll be working on the car for a bit, and a switch isn't that hard to come by. May as well test out your theory.
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  #69  
Old 05-28-2007, 01:26 PM
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postcard

Quote:
Originally Posted by svxistentialist
Super!!

Now, stage 2. How do we impose this programme on the TCU without having a laptop in the cabin all the time.

Answers on a postcard.......

The answer is to burn a modified EPROM in the same way that LAN has done for the ECU. If we had a way to modify the ROM then lots of things become possible.

I wonder if LAN's ECU memory adapter would work in the TCU? It might just need to be loaded with a modified TCU software.

Or there is another way: If you can tap out RS232 protocol on a morse key at 1953 bits per second. While Driving.
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Last edited by b3lha; 05-28-2007 at 02:02 PM.
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  #70  
Old 05-28-2007, 01:32 PM
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Quote:
Originally Posted by Nomake Wan
It's hilarious; I can keep up with the code jargon but when it comes to the details on the car I totally falter. Which pin is A4? I'll be working on the car for a bit, and a switch isn't that hard to come by. May as well test out your theory.
Find the black 20 pin connector on the ECU - I think it's the bottom one. Then find pin 4 - It'll be the one with no wire attached. Good Luck.
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Last edited by b3lha; 05-28-2007 at 05:50 PM.
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  #71  
Old 05-28-2007, 04:30 PM
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Quote:
Originally Posted by Nomake Wan

I'm just curious... wondering if duplicating the signal of the power switch on a USDM car would even work. I know we don't have a switch, but maybe we'll get lucky and our TCU will still accept the signal...

Hmm. Excellent work, though. It's been very cool watching you figure these things out. Hopefully we'll get EDM and USDM applications once you're done fiddling with your Japanese car, hahaha.
Nomake

We know from how they behave that there are at least two types of TCU. For simplicity I will call them the Euro type and the Japanese type.

The Euro type covers those markets that get the full-time [as in not rear assist] 4wd gearbox, same as the Japanese get. What is common to these markets is the fact that the TCU software inside delivers power mode on demand only, and also both speed sensors are in the gearbox.

The Japanese type has a different type of speed sensor 1, which is driven by the differential on front. This is the same input method as on your US system also. The fact that your US gearbox uses the same speed sensor 1 circuitry as the Japanese box may indicate that your software inside your TCU is similar to that of the native Japanese box. There is no guarantee it is the same, just hard to figure why they would bother to make two types of software, when one would work just as well for both markets.


US TCU control wiring

Hold a minute; Phil, can you please recheck your notes of when you traced the JDM control wire for grounding Pin 4? The plugs into the TCU are black, not yellow. Yellow connectors go to the ECU

Pin 4 of B59, a 22 pin yellow connector plugs into the ECU. If this is the control pin, then it is controlling it [power mode] through the ECU.

I had thought you might be talking about pin 4 of B66, which is a 20 pin black connector plugging into the TCU. Pin 4 of this block is also not in use on the US control circuit, see the pdf above.

We need to know which one is earthed by your JDM console switch before we proceed with any experimentation.

Joe
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  #72  
Old 05-28-2007, 05:09 PM
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Quote:
Originally Posted by svxistentialist
Nomake

We know from how they behave that there are at least two types of TCU. For simplicity I will call them the Euro type and the Japanese type.

The Euro type covers those markets that get the full-time [as in not rear assist] 4wd gearbox, same as the Japanese get. What is common to these markets is the fact that the TCU software inside delivers power mode on demand only, and also both speed sensors are in the gearbox.

The Japanese type has a different type of speed sensor 1, which is driven by the differential on front. This is the same input method as on your US system also. The fact that your US gearbox uses the same speed sensor 1 circuitry as the Japanese box may indicate that your software inside your TCU is similar to that of the native Japanese box. There is no guarantee it is the same, just hard to figure why they would bother to make two types of software, when one would work just as well for both markets.


US TCU control wiring
I believe, from looking at photos, that all the TCUs are the same in terms of hardware. But I think that the Euro, JDM and USDM markets all got different software. The Euro box is a VTD unit with both speed sensors in the gearbox. The USDM box is a transfer-clutch unit with one speed sensor in the diff and one in the gearbox. The JDM box has the Euro-style VTD with the US-style speed sensors. There is probably another software for the USA FWD cars. That's four different versions of the software.

But they didn't write each version from scratch. I'll bet they started with a base software for a Legacy and tweaked it for the SVX and then tweaked it some more for each market. I would expect to see a lot of similarities between the different versions.

Quote:
Originally Posted by svxistentialist
Hold a minute; Phil, can you please recheck your notes of when you traced the JDM control wire for grounding Pin 4? The plugs into the TCU are black, not yellow. Yellow connectors go to the ECU

Pin 4 of B59, a 22 pin yellow connector plugs into the ECU. If this is the control pin, then it is controlling it [power mode] through the ECU.

I had thought you might be talking about pin 4 of B66, which is a 20 pin black connector plugging into the TCU. Pin 4 of this block is also not in use on the US control circuit, see the pdf above.
Sorry. You're right Joe. As you said, I meant Pin 4 of B66 of the TCU. Glad you're checking on me. I've been reading assembler code too long and my brain is fried.
It's wired like the Aussie/Euro version, except change the word "economy" to "power" and chop off the circle-A connection that triggers the Econ light. Sorry for leading you astray, Nomake.

http://www.subaru-svx.net/photos/files/oab_au/13732.jpg
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  #73  
Old 05-28-2007, 05:25 PM
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Joe,

You have suggested that the US and JDM utilises basically the same TCU. Whereas the JDM and the US are the same. Your reasoning being based on different locations for the speed sensors involved.

I had great difficulty putting to rights. incorrect information published by Harvey regarding the operation of solenoid valve C and the US clutch arrangement. In the process of this rather torrid exercise, it was established that the US system utilises a normally closed C to operate the centre clutch, whereas the JDM and Euro systems use a normally open solenoid.

As a result of this arrangement, the same TCU could be used for both systems. This would appear logical and confirmed by the different solenoid configurations, as is used to operate clutch, or alternatively centre differential as are involved.

On the basis of this, it would seem illogical to propose that there is a difference between the JDM and Euro systems, when the only requirement is the provision of a manual switch, for power mode in the JDM system. This surely would not involve extensive circuit or software changes.
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Old 05-28-2007, 05:32 PM
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FORGET ALL THAT!

I just ran an experiment on my car... and it was a SUCCESS!!!

I'll provide pics at the end, but for now I'll just explain what I did. I pulled the harness out of the bottom of the TCU, sure enough position 4 was missing a wire. So I took a piece of wire from my tranny resistor project, coiled it up, and put it in through the back of the harness, then put the harness back into the computer. As for ground, I rememebred that the ECU goes into diagnostic mode when you ground pin 2 on the harness... and to do that you put the end of that blue wire in it.

So I coiled up one of the blue wires with the end of my wire. Starting the car saw no change, backing out of the driveway was no different... but damn. I put it in Drive and the POWER light came on and just... it just WENT. Holy crap. I did a test drive around the block and it was just so solid. Having POWER mode on like that is just such a cool feeling.

So I have confirmed that grounding pin A4 on the TCU does in fact grant you unlimited POWER mode whether you have a JDM car or a USDM one. Can't comment on the UK ones, but my thought is this: if they just didn't put in the switch in the USDM TCU, then why would the TCU in the EDM models be different? It's so much easier to just reverse the switch function! If the "POWER" switch on JDM models grounds A4, then why can't the "ON" position for the Economy switch just be an open circuit for pin A4, and the "OFF" position be ground?

Dunno. Anyway, it felt awesome, that was a very cool experiment. I'll have to rig up something more permanent real soon.
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Old 05-28-2007, 05:41 PM
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Quote:
Originally Posted by Nomake Wan
FORGET ALL THAT!

I just ran an experiment on my car... and it was a SUCCESS!!!

I'll provide pics at the end, but for now I'll just explain what I did. I pulled the harness out of the bottom of the TCU, sure enough position 4 was missing a wire. So I took a piece of wire from my tranny resistor project, coiled it up, and put it in through the back of the harness, then put the harness back into the computer. As for ground, I rememebred that the ECU goes into diagnostic mode when you ground pin 2 on the harness... and to do that you put the end of that blue wire in it.

So I coiled up one of the blue wires with the end of my wire. Starting the car saw no change, backing out of the driveway was no different... but damn. I put it in Drive and the POWER light came on and just... it just WENT. Holy crap. I did a test drive around the block and it was just so solid. Having POWER mode on like that is just such a cool feeling.

So I have confirmed that grounding pin A4 on the TCU does in fact grant you unlimited POWER mode whether you have a JDM car or a USDM one.
WooHoo!
Quote:
Originally Posted by Nomake Wan
Can't comment on the UK ones, but my thought is this: if they just didn't put in the switch in the USDM TCU, then why would the TCU in the EDM models be different? It's so much easier to just reverse the switch function! If the "POWER" switch on JDM models grounds A4, then why can't the "ON" position for the Economy switch just be an open circuit for pin A4, and the "OFF" position be ground?
It has been suggested before, but that is not how it is shown on the wiring diagram. It was also suggested once that economy mode simply locks out the power mode from engaging. This would be a trivial change to the ECU software. (It could be done by changing a single bit from 1 to 0).

Thanks for helping out with the research. You've made an important discovery that needs to go in a howto or something.

Now you know why I keep the power button on ALL THE TIME!!!
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1994 Alcyone SVX S40-II
2004 Subaru Legacy 2.5 SE Sports Tourer
1996 Subaru Legacy 2.2 GX Wagon
1988 Subaru Justy J12 SL-II

Last edited by b3lha; 05-28-2007 at 05:57 PM.
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