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1996 Subaru Legacy Outback wagon, 05/96, 2.5L
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Discussion Starter #1
My 96 Outback 2.5L automatic just gave me some trouble on a 2 hour highway drive. I was driving with cruise control on and sped up at one point to get ahead of a car. I think the car dropped down into 3rd to get the needed acceleration but then never went back into 4th. I drove it the rest of the way back (1.5 hours) after checking the trany fluid level. At 70 mph it's running at 4200 rpm and drinking lots of gas. Car didn't overheat, no trany heat warning, just high rpms.

I've checked the code that popped up, P0740 and found it might be the solenoid B (yes?). Using this great post,

http://www.subaruoutback.org/forums/99-do-yourself-illustrated-guides/50808-duty-b-solenoid-replacement.html

I was able to measure the resistances from the solenoid B and they check out at 16ohms. Is it possible that it is still bad? Could it be the TCM? The wires to the TCM also measured 0 ohms, so a wire short doesn't seem likely. I also disconnected the battery for 20 minutes and then tested it on the highway for a mile, codes didn't pop up but it still wouldn't shift into 4th.

I changed the trany fluid and filter around 1500 miles ago, everything looked fine inside, no build up of shavings, or anything. Since then, I've driven the car on a long round trip (5 hours one way) and all over town. Before this, there was no slipping and only a very minor noticable shift between 1st and 2nd. Any suggestions?
 

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2014 OBW 3.6R Limited, 1997 OBW 2.5L Auto (sold, but not forgotten), and 1991 Ford F150
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1,525 Posts
I was able to measure the resistances from the solenoid B and they check out at 16ohms. Is it possible that it is still bad?
Yes, it could still be bad. The electrical function of the solenoid can be good but there can be a mechanical failure. When I was diagnosing mine, one poster suggested that when a duty B solenoid fails, it is often because of debris lodged inside it. Assuming that is correct, I believe he was implying that a mechanical failure is more common than an electrical one. This may be what happened to yours ... can't say for sure and I doubt if anyone can.

If it was me, I'd probably go ahead and replace the solenoid and hope for the best.

Good luck.

P.S. I'm leaving for a two week vacation, so won't be able to respond to any questions after tomorrow afternoon. Please follow up with what you end up doing and whether or not it is successful. I'll check in after I'm home from the trip to hear (hopefully) the good news.
 

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1996 Subaru Legacy Outback wagon, 05/96, 2.5L
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5 Posts
Discussion Starter #3
Thanks, RobLog. I'll have to drop the pan (again) and replace the part. Does anyone else have any suggestions? What's the possibility that it could be a speed sensor? I don't yet know enough about the function of the speed sensors so I'm not sure how to rule them out. Related?
 

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1996 Subaru Legacy Outback wagon, 05/96, 2.5L
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5 Posts
Discussion Starter #4
Fixed!

I dropped the pan after receiving the new part. Much to my surprise, I found one of the bolts that held the solenoid in had rattled its way out and was sitting in the bottom of the pan. That may have been the source of my problems as this missing bolt would have kept the solenoid from having the proper seal. However, I didn't want to mess around so I put in the new part and took the car for a test drive and it worked perfectly, dropping into high gear with low RPMs. Kind of annoying and expensive that this malfunction happened, but I'm pleased to have solved it easily. Thanks again, RobLog.
 

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2014 OBW 3.6R Limited, 1997 OBW 2.5L Auto (sold, but not forgotten), and 1991 Ford F150
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1,525 Posts
Great news that it's fixed. I agree that the missing bolt would prevent the solenoid from sealing and doing it's job. Assuming nobody had ever touched it, maybe it was mis-torqued at the the factory ... or maybe it just happened for no good reason.

It's unlikely you could have returned the new solenoid as most places have a no-return policy on electrical parts, so it's just as well you used it.

Congrats.
 
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