Jump to content

Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse

- - - - -

4EAT speed sensor failure?

  • Please log in to reply
1 reply to this topic

#1 dashton


    USMB Regular

  • Members
  • PipPipPip
  • 43 posts
  • Springville, Utah

Posted 03 November 2003 - 12:52 PM

The AWD on my auto trans 1990 Legacy has never worked since I purchased it two years ago. I’ve been though the whole system – removed the extension housing and checked the clutches, seals, etc. and still nothing. This summer I finally wired in a switch that cuts out the duty C solenoid to try and force it into four wheel drive. I finally had a chance to test it this weekend with the first snow and it works great! But, my AWD is still dead. Initially I thought it was because of a stuck or bad duty C solenoid, and that the switch just forced it loose, but I’m getting nothing from the “computer controlled system” even when it’s stuck in the snow – just one front wheel sits and spins. This leads me to believe that there’s something else wrong, because as soon as I hit the 4WD switch it digs itself out and goes like crazy. (very fun, by the way)

Now here’s a little blurb I found on the endwrench.com:

"4EAT Speed Sensors
If you are in the process of diagnosing delayed or erratic shifting on a 4EAT transmission, pay close attention to the comparison of readings between speed sensor 1 and speed sensor 2 as displayed on the Select Monitor. If these sensors are working properly, the two readings should be close, but are rarely absolutely identical. If, however, in the vehicle that you are driving, you notice that the speed sensor 1 signal and the speed sensor 2 signal are always precisely identical, there may be a malfunction in the signal or circuit from one of the sensors. When the transmission computer senses a failure in one of the speed sensor circuits, it may substitute the other sensor’s reading in the display of the Select Monitor. This is why the two readings would be identical.”

Could I have a bad speed sensor that is causing me to lose the AWD? It would seem to me that if the computer substitutes the signal if the sensor isn’t working then I would lose the AWD (since it’s supposed to engage when there’s a difference in the two signals). I’ve never had a trouble code for the AT (except when I put it in 4WD, because I cut out the solenoid) I would assume if the computer thinks the VSS is bad that it should set a code.

Has anyone else had a problem with a speed sensor? Does anyone know how to check it other than take it to the dealer and have it scanned? Any help would be greatly appreciated. Thanks. Dave

#2 Legacy777



  • Moderator
  • 12,810 posts
  • Houston, Tx

Posted 03 November 2003 - 09:29 PM

It's possible, I would think it would throw a code or something. You can check the TCU codes yourself. Instructions are on my site.

Without a select monitor it would be difficult to tell for sure.

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users