[ntippet]

Yeah shouldn't be too difficult to trace the solenoid pin from the connector back to the output of the transistor.
Take some photos, would like to see the inside of the TCU, don't feel like taking mine out.

Have fun with the lockup, it does make a difference, I find it much more fun in the snow.
Automatic control of the transfer clutch makes the car much too boring and stable/predictable.
But that's why it works so well.

 

[plain OM]

I have the older style, and have confirmed I have the older valve body.

I presume you're referring to the replacement transmission.

Looking at the photo, I'm wondering: Where's the spin-on filter mount? It looks as if there's a plug over it. Or is it plugged temporarily in the picture?

 

[CNY_Dave]

H6 vehicles have the filter remoted to the front fender, under where the battery fits.

 

[plain OM]

Ah yes, I didn't remember it's with the H6.

 

[ntippet]

Mine is also remotely mounted there.

 

[plain OM]

Yes, now that you mention it, I also recall there were some 2.5s in 2004/5 with the filter in the LF fender. It had me way off in a thread some time back. Sorry for the diversion.

 

[CNY_Dave]

This weekend I will probably get as far as adding leads for a meter and measuring my TCUs signals, and if they (voltage) are similar to the 04 voltages posted by ntippet, I'll presume inverting the existing signal is reasonable.

Maybe I'll get as far as pulling the TCU again (easy) and IDing the actual solenoid driver chip.

 

[CNY_Dave]

OK, some progress.

Have my TCU out, have traced the circuits for the Duty C output.

Device is a Sanken Electric SI 5151s.

Similar to the hitachi device above, but opinout is:

1- GND
2- SIGNAL IN
3- Vo (output)
4- Diag (what the TCU uses to tell if the solenoid circuit is shorted or open)
5- Vs (presumably +12V)

SIGNAL IN can be a TTL or CMOS input, I'm thinking of snagging an inverter (will have to measure if these are +5V or 3.3V circuits) and just invert the signal to the driver.

This driver can source 1.8A, 1.5W as installed without a heatsink (18W with).

I wonder if I can find an inverting driver I can use instead?

Other driver devices on the board are 5155s (2.5A) and 5153s (2A but built-in zener).

Links I found that led to the info-

PGMFI.ORG - Grassroots ECU Development - Library . OBD1CivicIntegraECUs

http://wikitest.pgmfi.org/twiki/pub/Library/OBD1CivicIntegraECUs/SI-5151S.pdf

http://www.littlediode.com/datasheets/pdf/Datasheets-SI5/SI5155S.PDF

SI-5153S datasheet, Pinout ,application circuits High-side Power Switch ICs [With Diagnostic Function, Built-in Zener Diode] SI-5153S

 

[CNY_Dave]

Finding pwr and gnd would be a lot easier if I could ID any of these ICs:

Mitsubishi M59550 FP, and M59350

No logo, marked 5223, I don't think it's a MAX5223.

The 59350 might be a watchdog timer/power IC.
The connections make sense.
M59350FP pdf, M59350FP description, M59350FP datasheets, M59350FP view ::: ALLDATASHEET :::

 

[CNY_Dave]

A thought occurs to me- if I invert the signal going to the solenoid driver, I may also have to invert the monitoring signal from the driver to the microprocessor.

I just noticed something else- the FWD fuse does NOT connect the TCU pin to +12V, it connects it to ground.

 

[CNY_Dave]

Also, to avoid activating a code/flashing AT Temp light, a resistance of something less than 30k ohms needs to be between the solenoid output and ground, the open circuit sensor has a max trip resistance detected of 30k ohms.

No power resistor required, and need never be switched out of the circuit.

 

[plain OM]

I just noticed something else- the FWD fuse does NOT connect the TCU pin to +12V, it connects it to ground.

That's correct. It connects the pin to ground. The fuse is described in the FSM as the 'FWD [or AWD] switch' and is shown connecting to ground in the wiring diagrams.

 

[CNY_Dave]

Well, my temp mod is done.
Wired up a DPDT center-off switch so I have:
- normal connection
- transfer solenoid disconnected to give me front-wheel-drive
- FWD switch active, which gives me 'locked' AWD.

I went by the specs on the driver chip, which said a 30k resistance would keep the open-circuit alert from tripping, wired in a 10k, apparently iot does need to be less than that.

I have GND and the sig from the TCU coming up to where I can get to them, so I can add a resistor and see where the cutoff is.

I also have a set of voltage measurements to compare against (at some point) for all gears, at idle, mid-throttle, and full-throttle, measured AC and DC.

Looking at the valve bodies, 2003 vs 2004, no visible differences.

There are a few external differences on the bellhousing, though.

 

[ntippet]

Getting closer to something custom.
Does your resistor keep the AT Oil light from tripping?

 

[plain OM]

I also have a set of voltage measurements to compare against (at some point) for all gears, at idle, mid-throttle, and full-throttle, measured AC and DC.

This is weird. Both transmissions appear to be the same, i.e, earlier Phase II, yet they respond in reverse to the duty cycle signal from the TCM. Something just doesn't ring right.

In 2003 and 2004, two 4-speed transmissions were used; one was the 4EAT with the multi-plate clutch transfer system, and the other was the 4EAT with the VTD transfer differential, which was used with "VDC" cars. This has me wondering if it's possible that the VTD version might have used a reversed duty cycle signal-to-clutch pressure relationship all along, and could the replacement tranny actually be different at the back end while still appearing the same in terms of the valve body? Not likely, but what else could explain the reversed response?

Be interested in the comparison between the Voltages measured on your car compared to others.

 

[ntippet]

Are you pouring through the service info on the 03' and 04' looking for the difference?

 

[CNY_Dave]

I am fairly certain it's not a VDC transmission, I think there were several pins I have checked that are in different places on a VDC trans.

The 10K resistor is I guess too large to prevent the tripping of the AT light and flash.
Gives me an indicator I have it in 'Front' WD mode. The FWD light comes on to tell me I'm in 'Four' WD mode too.

I probably won't go through the '04 manual, I need to figure out either a transistor inverter circuit or mod the TCU itself with an inverter gate. I'll have to desolder the entire 5-pin driver to lift just the one (input) pin, and might have to invert the monitoring output as well.

The subaru dealer confirmed that '04 is different, as have the measurements and mods by ntippet.

 

[CNY_Dave]

Wonder if anyone else will be able to read this, heh.

 

[ntippet]

CNY if you have a multimeter capable of reading % you should add that to your chart.
Will give you the actual duty cycle the TCU commanding, otherwise you would have to infer that from the voltage readings.
Since the DC voltage readings are just taking an average of the highs and lows from the digital PWM square waveform.

plain OM I looked up the part #'s for the transfer solenoid, 03' and 04' are definitely different.

03' - 31942AA103 (spec'ed for 99-03')
04' - 31942AA130 (a bulletin 16-67-04 was released to replace 31942AA120 with 31942AA130, you should know though you have posted on this subject in the past)

New style solenoid started production in October of 2003 with transmission number 012485.

Edit:
Have been trying to find some good photos of these solenoids & differences.
Not much luck but came across an interesting thread & it looks like the Russians have also been mixed up on the 03' - 04' change as well.
Best viewed through Google translator.
http://forums.drom.ru/subaru/t1151877849.html

 

[ntippet]

CNY I am starting to think if you take the valve assembly and solenoid off your bad 03' tranny and swap it into the new one it may work correctly.

As plan OM noted the transmissions themselves haven't really changed at all.

I would bet the differences are not only in how the solenoid is controlled but also the internal valving control & fluid control between duty solenoid/control valve/feed to the clutches.

Since the parts are small valve assemblies, including the solenoid, they may be swappable.

Unfortunately I do not have the 2 different parts sitting on a bench so I can confirm these suspicions.