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
 

Photo
- - - - -

trouble code 31 on EA82 SPFI


  • Please log in to reply
7 replies to this topic

#1 aiiadict

aiiadict

    USMB Regular

  • Members
  • PipPipPip
  • 52 posts
  • sacramento

Posted 02 April 2011 - 07:43 PM

Says throttle position sensor is acting up.

I checked the sensor without connector plugged in. Everything with sensor is OK.

I do troubleshoot on page 62 in FSM. resistance between terminal 26 and 35 is supposed to be 3.5k to 6.5kohms. I get 4.25k.. so thats OK

I check resistance between terminal 25 and 35. Manual says its supposed to be less than 1k when throttle closed. I get 220ohms. so that's OK

Manual says it should be greater than 2.4kohms when throttle is fully open. I get 3k ohms. so that's ok too...

Next step says:

"check if terminals 25,26, and 35 are open or disconnected"

NO--->replace ECU

YES--->repair terminal or harness

-----------------------------------

I don't understand this step. How do I check if they are open or disconnected? IE, one lead of multimeter on the pins one by one, but what does other lead of meter go to? Am I checking the entire harness, IE from the throttle position sensor to the ECU connector???


Rich From Sac

#2 GeneralDisorder

GeneralDisorder

    Elite Master of the Subaru

  • Members
  • 20,280 posts
  • Portland

Posted 02 April 2011 - 07:50 PM

Well - since you get good ohm readings for the prior steps you can safely assume they are not open or disconnected - otherwise your meter would read infinity. Thus you answer "NO" to that step.

GD

#3 aiiadict

aiiadict

    USMB Regular

  • Members
  • PipPipPip
  • 52 posts
  • sacramento

Posted 02 April 2011 - 08:09 PM

in the manual, NO leads to "REPLACE ECU"... I am doubting that the ECU is bad. When electronics fail, they usually fail to the point of not working...

Update: I was watching the ECU light flash. I pulled the throttle all the way open. the light starts flashing specification code (meaning computer and sensors OK). I release throttle. Error code 31.

I pull throttle all the way. Specification code, no errors. Slowly close throttle. It flashes spec code until the idle switch gets pressed within the sensor... then back to code 31

Any ideas besides replacing computer? I guess I'll grab one at the junkyard next time I'm there... The engine runs great. Starts right up. Cimbs hills, Idles fine.

Rich

#4 GeneralDisorder

GeneralDisorder

    Elite Master of the Subaru

  • Members
  • 20,280 posts
  • Portland

Posted 02 April 2011 - 08:16 PM

ECU's and TCU's for Subaru's both have a tendancy to fail in specific and usually not fatal ways. Specific driver transistors or capcitors will die leading to a failure in a sensor or solenoid circuit but not a failure in the overall function of the computer. Thus you get a code for the bad circuit or something doesn't work right but it still runs. This has happened with a lot of the older TCU's - the transistors will die leading to duty solenoid codes and failure of specific functions but will still otherwise work. Recently I saw a '93 with a TCU that had a duty-A solenoid code. The solenoid was fine - the driver circuit transistor in the TCU had failed. It drove find but the TC wouldn't go into lockup.

GD

#5 naru

naru

    1000+ Super USER!

  • Members
  • 1,745 posts
  • under the bridge

Posted 03 April 2011 - 02:11 AM


Next step says:

"check if terminals 25,26, and 35 are open or disconnected"

NO--->replace ECU

YES--->repair terminal or harness

-----------------------------------

I don't understand this step. How do I check if they are open or disconnected? IE, one lead of multimeter on the pins one by one, but what does other lead of meter go to? Am I checking the entire harness, IE from the throttle position sensor to the ECU connector???


Rich From Sac


I think they are referring to checking the integrity of the connection between the ECU and the wiring harness as per page 44.

It would have been better(but harder) to measure resistances at the ECU plug like the manual suggests.That way harness gets checked at the same time.

IMO,your code may be caused by high resistance on the throttle sensor ground(35).I think the idle switch pulls the throttle sensor voltage high because of the poor ground.

Or,the potentiometer has a dead spot at idle.

#6 aiiadict

aiiadict

    USMB Regular

  • Members
  • PipPipPip
  • 52 posts
  • sacramento

Posted 06 April 2011 - 11:48 AM

RE: Naru (and everyone else who is kind enough to reply)

Thanks for the info. I will do some more tests on the harness.

The injector + and - were throwing a code, abnormal output. I soldered in 2 new wires between ECU and injector, made the code go away...

Seems strange that the wires could go bad like this. Maybe they got water underneith the insulation and corroded? I've had year 1950 vehicles whose wiring was fine... I guess none of them were that sensitive to faults though.


I'll report what I find later today... Have fun!

Rich

#7 MilesFox

MilesFox

    Catch this Fox!

  • Members
  • 10,299 posts
  • Madison/Milwaukee, WI

Posted 06 April 2011 - 08:48 PM

I would say check for corrosion and clean the contacts in the connector.

second, there is a variable resistor inside the throttle pos sensor, with copper brushes that ride against them. I would suggest disassembling the TPS and cleaning the contacts and the resisotor strips(like a printed circuit)

I have had these troubles and cleaned them with better results. I have seen corrosion inside these units as well. use an electrical contact cleaner and some dielectric grease, or swap out the whole TPS from a less mile/newer/less corroded donor car.

#8 aiiadict

aiiadict

    USMB Regular

  • Members
  • PipPipPip
  • 52 posts
  • sacramento

Posted 11 April 2011 - 02:11 PM

I tested from ECU to TPS, everything was at about 4ohms... I adjusted the TPS again, and trouble code went away! The idle switch wasn't coming on at the correct time.

The ECU is happily flashing 5. Thanks for the help guys!

Now to get a speed sensor hooked up.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users