Hi Folks, 99 outback , 2.5 doc, 93000 miles. Just had new head gaskets installed, engine was pulled, now mechanic reports tranny problems. Automatic transmission high temperature warning . Code says circuit fault for high pressure solenoid. It's not shifting right, I think he said it's going from 1st to third. He looked pretty thoroughly for any loose or broken connections, binds etc. but he really doesn't know where to go from here. Any help would be appreciated. Thanks, Bob

Hi Folks, 99 outback , 2.5 doc, 93000 miles. Just had new head gaskets installed, engine was pulled, now mechanic reports tranny problems. Automatic transmission high temperature warning . Code says circuit fault for high pressure solenoid. It's not shifting right, I think he said it's going from 1st to third. He looked pretty thoroughly for any loose or broken connections, binds etc. but he really doesn't know where to go from here. Any help would be appreciated. Thanks, Bob

Sorry for bumping my own post but due to the server being down after my post I hoped for some help, thanks, Bob

SOUnds like the solenoid failed. DId he check it for opens ?

 

 

nipper

Hi Bob, fellow PAian.

 

Since the engine was recently removed a pulled connector

still comes to mind.

 

Forgive me I do not know the 4EAT you have very well,

but

 

The older 4EAT units had a resistor in the engine compartment

by the pass. side strut tower.

 

This resistor was in series with one of the line pressure

solenoids and

was brought into play by the TCU to prevent hash shifts.

 

Maybe this resistor became unplugged (damaged) during the

removal/instal.

 

I may be all wet on this one, but if it is "open" it could trigger the fault code.

Hi Bob, fellow PAian.

 

Since the engine was recently removed a pulled connector

still comes to mind.

 

Forgive me I do not know the 4EAT you have very well,

but

 

The older 4EAT units had a resistor in the engine compartment

by the pass. side strut tower.

 

This resistor was in series with one of the line pressure

solenoids and

was brought into play by the TCU to prevent hash shifts.

 

Maybe this resistor became unplugged (damaged) during the

removal/instal.

 

I may be all wet on this one, but if it is "open" it could trigger the fault code.

Thanks to both you and Nipper, I'll be following up on both options, as always I appreciate the input. (Too bad we lost the Rolling Rock brewerey)

Thanks and good luck Bob, please keep us updated.

 

 

Yea, RR is no mo a Latrobe Legacy they brew Sam Adams now.

Hi Folks, 99 outback , 2.5 doc, 93000 miles. Just had new head gaskets installed, engine was pulled, now mechanic reports tranny problems. Automatic transmission high temperature warning . Code says circuit fault for high pressure solenoid. It's not shifting right, I think he said it's going from 1st to third. He looked pretty thoroughly for any loose or broken connections, binds etc. but he really doesn't know where to go from here. Any help would be appreciated. Thanks, Bob

Hi folks, two months after my post about tranny problems, two lyings mechanics and untold agrievation I find that the original mechanic did indeed crush the tranny pan and crack a solenoid. The problem now is that after replacing said solenoid and checking all other electrical possible problems, my car still shifts immediatly from 1st to third. The high at temp light still flashes and the computer code still says hi pressure solenoid but now the trany guy is stumpted. He's leaning towards it being a bad tcu but I don't think he really has a clue. Any help will as always be appreciated. Bob

Was it the hi pressure solenoid that was replaced? I am also thinking that when he pulled the engine he may have cocked the torque converter amd now its not sitting right.

Was it the hi pressure solenoid that was replaced? I am also thinking that when he pulled the engine he may have cocked the torque converter amd now its not sitting right.

Yes it was the high pressure solenoid. I'll mention the torque converter possibilitie. Thanks, Bob P.S. The tranny guy thinks it's an electrical issue rather than a mechanical or flud pressure problem. don't know if that helps on any direction to go on resolving it

Yours transmission was working before the swap, correct? Now its not. I don't think its electrical. There are lots of threads on this forum warning not to touch the torque converter during the swap.

You stated that the error code is still showing a circuit fault to the solenoid. I assume the tech has made sure that the voltage from the ECU is getting to the solenoid. If not, then that needs to be confirmed. If the voltage is ok then it seems there is a problem in the ECU for that circuit.

Do you mean *line* pressure solenoid? There is no such thing as the "high pressure" solenoid.

 

 

 

Check the connector at the top/front of the trans. There may have been a wire damaged in the swap

I just swaped to another trans and have the same issue with the line pressure solenoid(which I also swapped from a good working trans.) Code PO778(line pressure "B" solenoid electrical).

 

Mine has only 1st, 3rd gear,reverse ... I'm suspecting the harness as a possiblility...

 

So did you find out what cured your problem...?

I just swaped to another trans and have the same issue with the line pressure solenoid(which I also swapped from a good working trans.) Code PO778(line pressure "B" solenoid electrical).

 

Mine has only 1st, 3rd gear,reverse ... I'm suspecting the harness as a possiblility...

 

So did you find out what cured your problem...?

Interesting that you posted today, I was looking through old posts to find the code that my car was giving since I stll haven't gotten my problem resolved. The transmission guy who is working on my car is stumped. I've had the entire valve body with all solenoinds attached replaced, the ecu swapped out, the internal wiring harness pulled and checked, 3 tranny guys and an auto electric guy check it out and still no resolution. the reansmission is currently out of the car and disassembled. No problems internaly to cause the diagnostic code or drivability issues. I thought prior that it was starting and staying in limp mode but apparently the codes can be cleared, no dash lights and can run in 1st gear but when it tries to shift into 2nd. it goes into limp mode. The original problem that came after the pan had been damaged led us to think that after exhaustivly checking out possible electrical problems that when the pan had been crushed the tranny got starved for fluid due to the filter being damaged. Appaerntly thats not the issue so we are at a stand still going back to trying to figure out if there is a damaged solenoid or what. For anybody that might be able to help, the original valve body and tcu are back in the car. Sorry for the lenth of this post but it's been a long process trying to get this car fixed. Thanks, Bob

I will do pinout tests on the line pressure solenoid to chk if proper voltages are present at the harness.

 

connector B54 terminal 9 throttle fully closed(engine off)after warm up

voltage should read 1.5-4.0 volts

 

with throttle fully open(with engine off)after warm up should be less than 0.5 volts

 

resistance to body (ohms) 9-15~

 

It's also a possibilty that the internals of the trans could be blocking flow no allowing the solenoid to operate properly..

 

These specs are on an '03 outback 4eat phaseII w/o sportshift

[...]connector B54 terminal 9 throttle fully closed(engine off)after warm up

voltage should read 1.5-4.0 volts

 

with throttle fully open(with engine off)after warm up should be less than 0.5 volts [...]

You may already know this, but since you didn't say so... the "warm up" isn't just of the engine, it's the ATF that has to be at full operating temperature. In other words, idling the engine isn't sufficient -- the car has to be driven.

 

 

It's also a possibilty that the internals of the trans could be blocking flow no allowing the solenoid to operate properly.. [...]

Code P0778 is for an electrical problem, so if that's what you're referring to, flow shouldn't be an issue.

fixed it...after checking the line pressure pinouts.

I found the 2-4 brake duty solenoid not working...I then pulled the trans pan and looked it over and the connector was broken when I went to disconnect it. So I swapped another one from my good vavle body and and no codes ... and shifted flawlessly.......

 

In my effort to troubleshoot this problem I see that the code PO778 line pressure solenoid"B" electrical is very generic....I could be a number of issues...

fixed it...[...]

Congratulations.

 

 

In my effort to troubleshoot this problem I see that the code PO778 line pressure solenoid"B" electrical is very generic....I could be a number of issues...

P0778 issues are open or short circuits in the wiring/connectors/solenoid, or (rarely) a TCU-related failure. The cause can usually be located by visual inspection and/or use of a volt-ohmmeter.