Subaru Outback Forums banner

1 - 6 of 6 Posts

·
Registered
2002 Outback; 2003 Outback; 2004 Outback;
Joined
·
2 Posts
Discussion Starter #1
I know this topic has been discussed before (because I have already searched and read all the threads I could find on it), but here is a situation with my transfer clutch and duty solenoid that has me scratching my head...

My situation: 2004 Subaru Outback, Automatic, 2.5L, ~180K miles.
Symptoms/History:
Bought this car a few months ago, noticed after a few weeks that it was doing the familiar chugging with a quiet rubbing sound during tight, slow turns. Then this week the AT Temp light started flashing, so I found out how to read the TCM codes, and got a 79 - "Transfer duty solenoid open or shorted" code. Did a bunch of web and forum surfing, and decided to try inserting the FWD fuse to see what the symptoms were. AMAZINGLY (to me anyway), there was absolutely NO chugging or rubbing sound, no matter how slow I went in a tight turn. In fact, I found a cul-de-sac and did circles with the wheel all the way left, and then all the way right, and NOTHING - not any binding, chugging, rubbing, grinding... nothing.

So, this is why I am confused. With the FWD fuse OUT, I get slight binding and chugging in tight slow turns, which would seem to indicate that either the solenoid isn't working, OR the clutch plates are sticking. BUT, with the FWD fuse IN, it's smooth as a baby's bottom, which would seem to indicate that BOTH the transfer duty solenoid AND the clutch are working.

From what I'v read, I assume the TCM is applying a full ON (or full OFF) signal to the solenoid with the FWD fuse is IN, so the clutch would be FULLY DISENGAGED, whereas, with the FWD fuse OUT, the TCM is applying a pulse train to the solenoid, keeping the clutch SLIGHTLY ENGAGED during tight, slow turns. So, if the clutch plates are worn such that they are "stickier" (??) than they should be, that MIGHT explain why I get slight chugging with a rubbing sound during the slow, tight turns. BUT, that DOES NOT explain why the TCM is throwing a "Transfer Duty Solenoid" error code.

What do the experts say? Does this ring any bells, or give you any ideas? Thanks in advance for any help.

JimmyBoy
 

·
Registered
06 OBW 2.5, 05 Forester, had 03 H6 OBW
Joined
·
5,936 Posts
The connection to the solenoid is duplicated to a port internal to the TCU that looks at the voltage on the wire.

If it sees a voltage too high (presumably) it decides the wire is broken, too low and it thinks the wire is grounded.

Probably what is happening is that the solenoid is failing or the wiring is partially broken or partially shorted, the voltage is in a range that sets the error, but enough current is making it thru the wire/solenoid to do something.

On an 04 with an H6 I am sure, on a 4cyl I am less sure, that the solenoid with no voltage to it applies no power to the rear wheels.

If yours is like an '03 (+12V unlocks) the binding would make sense as a failing solenoid/bad wires.

If yours is like an '04 (0V, no voltage / grounded to unlock) the binding would likely be caused by something other than the solenoid.
 

·
Registered
03 H6 OBW & 06 WRX Sportwagon
Joined
·
17,711 Posts
well, have to ask, are all 4 tires the same size? brand? model?

any chance the rear diff or the transmission have been replaced?

how does the trans fluid look?
 

·
Registered
2002 Outback; 2003 Outback; 2004 Outback;
Joined
·
2 Posts
Discussion Starter #4
1 Lucky Texan - Yes, just verified - tires are all same brand/model/size; don't know about rear diff or trans - bought car used, with no maintenance records, but there is nothing obvious that would indicate either has been changed; trans fluid looked and smelled GOOD when I bought the car, but did a couple of drain-the-oil-pan ~4Qt changes anyway, just for good measure.

CNY_Dave - I think my next step is to find the right connector and pin, and back-probe the signal from the TCM to the solenoid. Are you saying that there is a separate wire coming BACK from the solenoid to the TCM that allows the TCM to monitor the voltage AT the solenoid? Or are you saying that the signal going from the TCM to the solenoid is fed to a monitoring circuit inside the TCM itself, before the wire exits the TCM, so the TCM "sees" the voltage (and possibly the current also) on the wire going TO the solenoid? If it's the former case, I could find that wire and look at it too. P.S.: What part of CNY are you in? I am 15 miles SE of Rochester, in what some people call "Western" NY.

Thanks guys!

Jim
 
1 - 6 of 6 Posts
Top