Subaru Transfer Duty Solenoid CODE

[Colec533]

My subaru has been acting up lately with the green power light flashing. I have had trouble with rough shifting (automatic trans) and the steering wheel being tough to turn usually when the car is warmed up. On a cold start when i first start it up and go for a drive the steering wheel is fairly loose and feels better but not like it used to when i first purchased the car. After the end of a hour drive it becomes very stiff and hard to turn. and for the first time today coming into a parking lot i think i experienced some torqe bind. After the light went out randomly when driving seemed to go away pulling into another parking spot. Manually scanned the codes with the black connectors under the dash and got a code 79 for “Transfer duty solenoid” could this cause some rough shifting? I also have to change my transmission fluid as it is a light brown i also noticed sometimes when going into park i hear a loud clunking noise. Symptoms only happen occasionally maybe 60/70% of the time. I put the FWD fuse in today to prevent any further damage and the steering wheel seemed to loosen up and so far drives better in FWD. i also read onlinenit could Be the wiring going to the solenoid how would i go about checking this to narrow it down to the solenoid?  

[idosubaru]

Solenoid is most likely failing, it happens sometimes.  That your FWD fuse works suggests the wiring is almost certainly fine, which is the suspected diagnosis anyway. 

Easy fix:  install a rock switch to switch between FWD and "locked" 4WD which is what you're experiencing with the torque bind.  Switch it there in snow or offroad, then drive in FWD nominally.  It's a great fix for some situations since it's essentially free and works every time. 

Or replace the Duty C solenoid.  Ideally you replace or address the clutches while it's apart for the job as well.  In the states here it's roughly $200 - $400 in parts if you're DIY or $700 - $1,000 to pay a shop to do it, largely depending on local prices and if you replace just the solenoid or solenoid and clutches. 

[CNY_Dave]

The computer can only detect if the circuit has too much resistance, or too little.

So either there's a bad connection, a developing short to ground, the solenoid is going 'open', or is shorting out.

Clunk while going into park is a sign the AWD is engaged more fully than it should not be, the 'wind-up' in the system is released when in N or P.

I'd at least check the connectors for tightness and pull them apart and check for corrosion.

 

What year is it? Older cars, +12V to the solenoid signals no lockup so loss of connection causes 100% lock and bind.

Newer cars, 0V causes no lockup, so a failure results in front wheel drive.

[idosubaru]

1 hour ago, CNY_Dave said:

The computer can only detect if the circuit has too much resistance, or too little.

So either there's a bad connection, a developing short to ground, the solenoid is going 'open', or is shorting out..

Testing is best in case odd things are present, but if the FWD fuse is working does that suggest the circuit is likely good?

[Colec533]

5 hours ago, CNY_Dave said:

The computer can only detect if the circuit has too much resistance, or too little.

So either there's a bad connection, a developing short to ground, the solenoid is going 'open', or is shorting out.

Clunk while going into park is a sign the AWD is engaged more fully than it should not be, the 'wind-up' in the system is released when in N or P.

I'd at least check the connectors for tightness and pull them apart and check for corrosion.

 

What year is it? Older cars, +12V to the solenoid signals no lockup so loss of connection causes 100% lock and bind.

Newer cars, 0V causes no lockup, so a failure results in front wheel drive.

It is a 2002 outback. 

[Colec533]

5 hours ago, CNY_Dave said:

The computer can only detect if the circuit has too much resistance, or too little.

So either there's a bad connection, a developing short to ground, the solenoid is going 'open', or is shorting out.

Clunk while going into park is a sign the AWD is engaged more fully than it should not be, the 'wind-up' in the system is released when in N or P.

I'd at least check the connectors for tightness and pull them apart and check for corrosion.

 

What year is it? Older cars, +12V to the solenoid signals no lockup so loss of connection causes 100% lock and bind.

Newer cars, 0V causes no lockup, so a failure results in front wheel drive.

Where would i find the connectors are they easy to access? 

[CNY_Dave]

22 hours ago, idosubaru said:

Testing is best in case odd things are present, but if the FWD fuse is working does that suggest the circuit is likely good?

Only good enough and at that moment.

Measuring the resistance cold then hot can be informative.

[CNY_Dave]

18 hours ago, Colec533 said:

Where would i find the connectors are they easy to access? 

At the TCU is one place, another is at the firewall right behind the throttle body.

There are pinout diagrams somewhere.

Oh, it could also be the TCU itself, the drive transistor for that circuit could be failing.

[Colec533]

On 6/27/2018 at 2:57 AM, CNY_Dave said:

Only good enough and at that moment.

Measuring the resistance cold then hot can be informative.

The FWD fuse worked for maybe a 5-minute drive and drove better but then all the sudden the light went out and it switched back into AWD and the green power light came back on flashing. It seems the car drove better when the light isn't on but I can still tell something is not right. But when it comes on I start to get worse symptoms clunking becomes worse and starts to happen when coming to a stop sometimes. Switching gears is a lot rougher when hitting the gas. Could this maybe be something to do with the back wheels engaging at the wrong time or do you think it's something worse? 

I've heard it's okay to drive with a bad solenoid short term could drive 1500/1600kms with a bad solenoid c likely damaged something else? or is that not considered a long time to be driving. 

 

[CNY_Dave]

If it is engaging too well it becomes harsher whenever anything changes in the drivetrain because it allows any 'windup' to suddenly dissipate.

If it's really harsh you may have tires too far out of matching diameter/circumference spec.

The solenoid itself won't damage anything else, but the binding can damage the CV joints and such. It puts a lot of strain on everything.

[idosubaru]

you checked fluid level and condition right?

how long you can drive depends on too many variables to say, more turns are bad, less forgiving surfaces are bad, straight driving is fine, mismatched tires may exaccerbate things, how long was it previously driven, was it towed improperly in a past life (common)....hard to say, but generally you can driven them a little while.

they do fail from binding - usually the ujoints in the rear driveshaft fail, or the internal drum shears off, i imagine a weak rear CV joint could also let loose since those fail on the offroad guys, but i haven't seen it happen strictly due to torque bind.

if you can't fix it soon, ideally you force it to "locked" and disconnect the rear driveshaft so you can just run it in FWD until you figure it out proper. 

[idosubaru]

4 cylinder or 6 cylinder? 
VDC or non-VDC trans?

i think for that year all JDM trans are VDC...or all JDM H6's anyway are VDC, but that is not the case in the US, so what do you have?

[Colec533]

5 hours ago, idosubaru said:

you checked fluid level and condition right?

how long you can drive depends on too many variables to say, more turns are bad, less forgiving surfaces are bad, straight driving is fine, mismatched tires may exaccerbate things, how long was it previously driven, was it towed improperly in a past life (common)....hard to say, but generally you can driven them a little while.

they do fail from binding - usually the ujoints in the rear driveshaft fail, or the internal drum shears off, i imagine a weak rear CV joint could also let loose since those fail on the offroad guys, but i haven't seen it happen strictly due to torque bind.

if you can't fix it soon, ideally you force it to "locked" and disconnect the rear driveshaft so you can just run it in FWD until you figure it out proper. 

I checked the fluid and it is fairly brown not red at all and a little cloudy, could bad fluid itself cause a solenoid c code to come up? if the code is present does that mean there is for sure something wrong with the solenoid ifself or the wiring? or could bad fluid throw the code and cause bad preformance when driving especially up hill a lot of clunking on the gas peddle and rough shifting when it shifts into gears while driving the car kind of jerks forward and switches into gear sometimes clunking. I plan to have the solenoid and a transmission drain and fill/flush done. 

I didnt have any binding symptoms until the green power light started to come on a lot more often when it first came on it came on flashing and went out when car was turned off and didnt come on for a week or two then it started to come on a lot more frequently usually at the end of a a hour - 2 hour drive. And the transmission starts to feel a lot worse and not preform properly.

Because the FWD fuse worked for a short period of time does that mean that my wiring is most likely fine?

Now it does not work at all when inserting the fuse. 

 

[Colec533]

5 hours ago, idosubaru said:

4 cylinder or 6 cylinder? 
VDC or non-VDC trans?

i think for that year all JDM trans are VDC...or all JDM H6's anyway are VDC, but that is not the case in the US, so what do you have?

Its a 4cyl 2.5 2002 outback, car is located in Australia. Not sure about the VDC how woulD i check this?