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  #16  
Old 11-05-2017, 11:49 AM
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Re: electrical problem

if a fuse is blowing as soon as you install it you have a direct short. you need to find out where that short is. look at a wiring diagram and disconnect all associated components related to that circuit. put the fuse in, if it blows you have a wiring issue, if it does not, start reconnecting the components till the fuse blows again and you have found your problem.
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Rebuilt P/S pump info... http://www.subaru-svx.net/forum/showthread.php?t=50918

If your car wont start info... http://www.subaru-svx.net/forum/show...ighlight=click
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  #17  
Old 03-05-2018, 07:49 AM
ian2120 ian2120 is offline
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Re: electrical problem

*buuuump*

So just got the car back from my shop; it was in primarily for non-electrical power steering issues and valve cover gaskets, but I also grabbed a TCU off of ebay and had them swap it in. I now have inverted shifting issues; with my original TCU, which was in the car when the "Christmas lights" voltage regulator failure occurred, I had the Power Mode light throwing codes for solenoids I have already replaced since the failure.

With the new TCU, I am stuck in what seems to be some kind of limp mode: I only have reverse and 3rd gear. Rowing through the gears manually provides no change. I also have no Power mode, nor is the dash indicating any present codes, although I haven't tried to pull them.

Any ideas as to what could be keeping me in limp mode? At this point I'm thinking ECU, and if I can pull it out and have a look at it, it might be easy to tell. Have a look at the pictures from the board of my old TCU:

IMGUR
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  #18  
Old 03-05-2018, 02:19 PM
oab_au oab_au is offline
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Re: electrical problem

There is no electrical connection to the gearbox, it is operating only on the manual shift lever.
Either the TCU is a dud or the plugs to the box are not connected properly.
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  #19  
Old 03-05-2018, 02:54 PM
ian2120 ian2120 is offline
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Re: electrical problem

Quote:
Originally Posted by oab_au View Post
There is no electrical connection to the gearbox, it is operating only on the manual shift lever.
Either the TCU is a dud or the plugs to the box are not connected properly.
Aside from swapping it, any way to do a quick test (aside from pulling the codes) without pulling it out? Should I try and put in the FWD fuse, and if so to what end?

Thanks for the input, I didn't realize that there is no electrical connection to the gear box!

**EDIT**

Reading more into it, it's likely that the TCU I got is running different firmware, per alcyone.org

Last edited by ian2120; 03-05-2018 at 04:33 PM.
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  #20  
Old 03-05-2018, 11:25 PM
oab_au oab_au is offline
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Re: electrical problem

I would still say its the TCU< or the plugs to the box.

Now it will only have R and 3 if there is no power to the solenoid pack in the box, the shift lever will select both R and the forward clutch, and as there is no solenoid action, they are all off so 3 gear.

So if you didn’t pull any of the plugs off, and only changed the TCU, I would say its a dud.

I can’t see the site that you linked to, but I can say that there were no firmware changes, other than the change to cover the different C solenoid that concerned the VTD cars, nothing that would cause your trouble.
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  #21  
Old 03-12-2018, 11:27 AM
ian2120 ian2120 is offline
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Re: electrical problem

Quote:
Originally Posted by oab_au View Post
I would still say its the TCU< or the plugs to the box.

Now it will only have R and 3 if there is no power to the solenoid pack in the box, the shift lever will select both R and the forward clutch, and as there is no solenoid action, they are all off so 3 gear.

So if you didn’t pull any of the plugs off, and only changed the TCU, I would say its a dud.

I can’t see the site that you linked to, but I can say that there were no firmware changes, other than the change to cover the different C solenoid that concerned the VTD cars, nothing that would cause your trouble.
Dud confirmed! Corrosion along the edges of the board and a pair of leaky capacitors

It has been replaced with a functional box, and I'm no longer in limp mode! But now my FWD light is on (fuse is not in). Any thoughts as to what my next troubleshooting steps are? I haven't seen anything on a quick search through the forums and . Again, all of my duty solenoids were replaced after my voltage regulator failure so I don't think it's any issue with that. Is it possible I just need to drive the car for a while now that the transmission won't be choking itself? Hoping that its not any issue with the diffs...

Thanks for all the help thus far!
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  #22  
Old 03-12-2018, 05:25 PM
oab_au oab_au is offline
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Re: electrical problem

Hi the first question is, did this only happen when you put the “ functional box” in?

The fuse is just a switch to turn the TCU on, turn the light on, and turn the center clutch off.
So to check I would put the car on some grass, select low gear and see if only the front wheels spin.
If it does, and you have not done any other work on it, you may have another faulty TCU. I don't think it is going t fix itself by driving it.

You can drive it in fwd, but be aware that if you allow the front wheels to spin too much it can break the front diff.
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  #23  
Old 03-14-2018, 08:10 AM
ian2120 ian2120 is offline
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Re: electrical problem

Quote:
Originally Posted by oab_au View Post
Hi the first question is, did this only happen when you put the “ functional box” in?

The fuse is just a switch to turn the TCU on, turn the light on, and turn the center clutch off.
So to check I would put the car on some grass, select low gear and see if only the front wheels spin.
If it does, and you have not done any other work on it, you may have another faulty TCU. I don't think it is going t fix itself by driving it.

You can drive it in fwd, but be aware that if you allow the front wheels to spin too much it can break the front diff.
Correct: the two prior "bad" TCUs did not trigger the FWD light, but this third "functional box" has, but this third box is the only one that seems to actually shift properly.

I'll find my way to some grass to do that low gear test ASAP!
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