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97 Legacy Outback - Check engine light, speedometer, mileage and trip don't work


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I was stopped at a stop light and noticed my car had stalled.  I started it back up and noticed it was running on 2 cylinders.  Not being able to get up enough speed on the highway, I pulled over, turned the car off and back on again and the engine power returned to normal.  But I still have a non-functioning speedometer, mileage counter and trip mileage.  The check engine light is still on and the RPMs stop at 4.5k.  If I try to rev the engine above 4500 it oscillates and doesn't go any more.

 

We have had some very cold weather here in CO and also I was rear ended and pushed into a car in front of me.  It pushed my radiator back an inch and a half or so.  Not sure if that would have anything to do with it.

 

Just wondering if anyone knows what the problem might be.

 

Thanks

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I have seen a similar condition one other time. Unfortunatly it was not on a Subaru. Like yours, it had been in an accident and repaired. It would have irratic changes in fuel pressure, random cylinder misfires, lights turning on and off, and the real laughable one was when we hit the key to start it and where the digital speedometer display is read "error" and the car would do nothing. To top it off, sometimes you would hit the key and it would run like new. During one of its episodes, my friend accidentally bumped into the front right fender while looking under the hood and immediately the problem went away. Looked and saw a wiring harness that I guess sustained some damage going to either the ECM or body control module can't remember which now it's been a few years. One of the wires was exposed and grounding itself out on the body creating a short. Fixed the wire and it never happened again. Hope this helps.

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The speedometer has a direct electrical connection to the VSS on the transmission, so if it isn't working there's either an issue with the vss or with the speedo head. I would suspect the vss first, it's threaded into the passenger side of the transmission. It's pretty easy to replace but it's often hard to get a wrench on if it's a manual trans. A failed vss would cause the stalling at stops because the computer uses it to control engine braking fuel cut. It shouldn't cause running on 2 cylinders and a 4500rpm rev limit though.

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  • 2 weeks later...

The above video was not the cause of my issue.  Does anyone know were the cable going to the transmission is located?  Also, there are other threads on this issue but nothing I found to be particularly helpful.  It was mentioned that something called the iacv might need to be cleaned, but I had trouble locating it on my 2.2l engine.  I did reset the ECU and the check engine light temporarily cleared and the rev limit problem went away for a while, but quickly returned after some driving.  Speedometer and mileage still haven't worked since I initially noticed the problem.

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I already told you the speedo is an isolated system. Fix the VSS, which I told you is threaded into the passenger side of the transmission, there is no cable, or fix the speedometer head, or fix the wires that connect the two. When the speedo is back working, then go after the check engine light and stalling issues.

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The vss did the trick and fixed all the problems.  They're over 100 bucks new so I got one at the junk yard.  However, the speedometer didn't come on after I replaced it until I got the car up to about 25 mph.  I then stopped and got goign again.  Then it was about 10, stopped again 5, etc.  I hope this doesn't keep happening.  Eventually it freed up but I suspect it might happen again if I let the car sit overnight.

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An unfortunate possibility is that the nylon speedometer gears are worn and slipping. These are considered by all but a few to be accessible only by pulling the transmission. Our Postal Legacys seem to eat them every 150,000 miles or so. The speedometers work intermittently for a while and then quit entirely. Hope this isn't what is going on for you.

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A failed vss would cause the stalling at stops because the computer uses it to control engine braking fuel cut. It shouldn't cause running on 2 cylinders and a 4500rpm rev limit though.

 

It absolutely will cause the Revs to be limited to about 4200 RPMs.

 

Also CAN cause running on 3cyls......#1 injector is cut out when ECU senses it can't properly control idle.....which if it thinks you are stopped when you are moving and RPMs are much higher than expected (cause your rollling when it thiks you are sitting still) it will do this to prevent runaway revving like from a major intake leak or other issue.

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An unfortunate possibility is that the nylon speedometer gears are worn and slipping. These are considered by all but a few to be accessible only by pulling the transmission. Our Postal Legacys seem to eat them every 150,000 miles or so. The speedometers work intermittently for a while and then quit entirely. Hope this isn't what is going on for you.

If that's the case, I'm perfectly capable of driving without a speedometer.  I disconnected the negative battery cable to reset the check engine code.  Once I drive it again I'll post back.

Edited by DavieGravy
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I just replaced the VSS2 speed sensor on my 1998 legacy for the "no speedo, no cruise control, check engine light, & flashing ATF temp on start up". The old sensor was flagged by the OBD2 scanner. The old VSS2 speed sensor was obiously bad when removed, & I'm glad I replaced the sensor when I did. The VSS2 sensor was almost froze up & I can see how that could cause more wear problems in the tranny with the VSS2 drive gears.

 

Proir to changing the sensor I did check the VSS2 sensor connector. Because the sensors run about $100 new.

 

Everything is working again with the new sensor.

 

In 1999 Subaru made changes to the tranny & the VSS2 is now of a more dependable style sensor.

Edited by prugs
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  • 3 weeks later...

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