erecker

Update: Bought identical replacement from car-part.com, removed all 'extra' wiring and switch and ohmed out the harness, all good. Installed new TCU and AWD is now working beautifully! Shifting still sucks but at least now I know that's not the TCU's fault. [lazy off the line unless preloaded, feels like too low line pressure at idle. shift 2-3 actually shifts 2-4-3. shifts around 6000rpm at full throttle and in 'power'. already changed fluid, added treatment, changed transfilter] PM to Presslab if he still wants the old TCU, everything works except no output to duty-c ever, so no AWD. I don't need the rom dump as I got an identical TCU - but I could provide the dump to you and save shipping if that's all you need?

Oh fun. Unplugging the harness to 'limp/3rd gear/4wd' mode worked, locked the system in 4wd. I ohmed out the harness and the duty-c, all's well there. Pin3 the sending wire on the TCU for duty-c showed B+ 14v at all times, and duty-c flash code persisted. I traced the wires out of the TCU, and found the previous owner had spliced the wire to B+. After removing this splice and restoring the harness to spec, 4wd is locked and voltage is 0v to duty-c. The power transistor inside the TCU that drives that pin3 was totally fried, scorched the circuit board, blew out a 391ohm 1watt resistor, and a diode. I cleaned up the circuit board and replaced the burnt out components, everything now ohms out good on the circuit board, but still no voltage on pin3. So the TCU is toast It is the HU model for 3.90 ratio turbo 4eat's, everything else works good as far as shifting so if anyone has a use for this TCU let me know I'll pass it on to you. For now I have installed a switch B+ to Duty-C to allow fwd and 4wd switching, this is inconvenient but I'd rather deal with fwd than with torque bind tearing up my clutch pack and tires. On the plus side this says the duty-c in the tranny is good, right? So this leads me to needing a new TCU with 'HU' on it for a 1994 Subaru Legacy Turbo Wagon AWD, 3.90 ratio (I believe..). Can anyone advise what part#'s to be looking for for the replacement? As I understand it I cannot put an NA TCU in due to gear ratio differences... Does this limit me to 1990-1994 Turbo AWD sedans&wagons for an acceptable donor? Thanks in advance! Eric

Thanks for the quick reply and great info John! Yes the speedo and odometer work correctly all the time. Yes the TCU 'power' codes flashed are definitely 24 and 32. I can add the following: I didn't know there was an EXISTING and a PREVIOUS codes registry... EXISTING codes read D-3-2-1: code 24, Duty C PREVIOUS codes read 1-2-3-D Code 24, Duty C Code 32, VSS1, Code 24, 32, 24, repeats. I'll visually check the VSS1 now, and its wire, that sounds simple. Is there an electrical test I can perform here to verify function? If I unplug the large transmission harness to enter 'limp' mode, verify if it 'should' still split 50/50 torque even with this VSS1 is failed?

Hello, I'm the proud owner of a new '94 awd turbo wagon. The thing is, I believe the AWD is not working at all. I punch it on snow from a stop, the front wheels spin and spin forever. It does not feel like my previous subies and I don't feel the rear end at all. The front wheels will burn all the way thru 1st gear on dry pavement. I've verified the proper hardware is installed underneath - tail end of tranny, drive shaft, diff, rear axles. I've verified the FWD fuse is not installed. I've verified installing the fuse will light the FWD indicator on the dash, and I pulled the fuse back out. The transmission code procedure is giving codes 24 and 32: Duty C solenoid Speed sensor 1 (VSS1) Additionally the Power light blinks 11 times when turning on the car. CEL light is off, ABS light is off, and ABS functions properly. I'm preparing to take the following action and would appreciate input from more experienced members of this community... 1) pull the main harness from the tranny to enter 'limp' mode forcing 50/50. Drive and see if rear wheels provide power now. -If so, look for TCU/harness issues and VSS1 issues. -If still no power, install an oil gauge at the test port on the tranny tail, expecting 0psi indicating solenoid stuck Closed(bypass/fwd). Replace solenoid, flush tranny, test again. -If PSI is present, flush tranny. If still no power, tear down tail inspecting for missing gaskets, torn basket, missing plates, check plate thickness, grooving thickness, oil feed line, etc. Does this sound sensible? Is there anythign else I should check before tearing the tranny down, laying in the snow? Finally anyone in Denver area with a garage I can use? haha Thanks in advance Eric