Kevin said:
Hmmm - my manual in the "Engine Section Transmission Module I/O Signal" around Pg 432 lists "Transfer Duty Solenoid" as B54 pin 15. See if you can find a similar reference in your manual.
OK, now we're definitely getting somewhere. I found the same section of the manual for my turbo Forester and it has uncovered some interesting facts. First of all, I do indeed have the correct pin. The "Transfer duty solenoid" (also referred to as the "AWD Duty Solenoid" in other sections of the manual) is on pin 4 of connector B56. So the wire location is definitely different (same color though!) from the non-turbo. Oddly, but importantly, the voltage expected on this pin is VERY different from the voltage expected on the non-turbo! It is almost backwards for some reason. When voltage goes UP on the TURBO version, the system apparently gets "closer" to 4WD. When voltage goes UP on the NON-TURBO version the system gets closer to FRONT wheel drive. Why would Subaru have changed it on the Turbo version? Seems odd.
According to the manual I'm supposed to see "more than 10.5 volts" in first gear, throttle fully open on the turbo version. (A more "4WD" situation) The NON-TURBO expects to see < .5 volts under the same test conditions. Another interesting fact is that the TURBO version has only 2.5-4 ohms of resistance vs. the 10-17 for the NON-TURBO.
These facts do help to explain the odd (or so it seemed at the time) results I obtained when trying the mod. When I cut voltage to the Transfer solenoid, I was essentially experiencing FWD instead of 4WD and the above implies that is what one would expect to see on the TURBO car. The fact that I gave 15-16 ohms of resistance to that wire, explains why I got a check engine light even though the car was running when I flipped the switch.
OK, that's all well and good, but what does this mean exactly? Does it mean that in order to force 4WD on the turbo model that I need to send a power signal to the solenoid while putting a 2 - 4.5 ohm resistor on the other side of that wire? That's what it looks like to me, but I'm not an electrician, I'm a programmer. And I discovered a long time ago that programming logic doesn't always work for electricity.
And I'm not going to try it unless someone who knows more than I do thinks that I won't blow anything up by trying.
Which leads me to another question. Is it possible I've already messed up something? Could putting those 15-16 ohm resistors on that wire from the tranny computer cause permanent damage? Sure hope not, but my Check Engine light is still on... [EDIT: As of this morning (6 July 2006), my Check Engine light is OUT, so it appears that I did NOT do any permanent damage]
So am I the ONLY turbo owner trying to perform this mod? Perhaps the "mod it" types who bought the turbo also bought the 5 speed and aren't interested? Oh well.
Thanks for your continued help in trying to figure out how to get this working on the XT! I think we're getting close. Sure hope this helps someone else out in the future.
Jack
Relevant section of the manual is attached (See Page 2)