Any input would be greatly appreciated:

 

My mom's '98 Legacy wagon 5-speed with 135,000 miles SHUT OFF as she was downshifting/decelerating while coming up to a traffic light. She restarted it, and the Check Engine Light came on. She mentioned smelling a weird, burning type odor (sorry that's all the description I have at this point).

 

Here's the weirder part: Her speedometer no longer moves! Just sits at "0".

 

My dad drove it around the block once she got home, and as he slowed to enter the driveway, it shut off again. He said the engine runs and drives fine, and other than the Check Engine Light and non-functional speedometer.

 

We're taking it to our independent Subie mechanic first thing tomorrow morning, but we're wondering if anyone here has any ideas in the meantime.

 

Is the speedometer registered and controlled electronically? Blown fuse= burning odor? What would cause the car to suddenly shut off and could it be related?

 

Knock sensor was replaced about a month ago, but other than that we've not had any major issues with the car in quite some time.

 

Thanks,

Brian

I bet the CEL is being thrown for the VSS. The VSS is the speed sensor that tells the car how fast it's going. Hopefully, it's just that the sensor broke. However, some transmissions break the little plastic gear inside the tranny and that in turn throws off the VSS and makes your car throw a CEL. Replacing that gear is a very time involved job. The sensor isn't as bad.

 

The first thing I'd do is make sure the speedo cable is plugged into the cluster okay. After that though...

Alternator failure sometimes causes seemingly unrelated problems.

I bet the CEL is being thrown for the VSS. The VSS is the speed sensor that tells the car how fast it's going. Hopefully, it's just that the sensor broke. However, some transmissions break the little plastic gear inside the tranny and that in turn throws off the VSS and makes your car throw a CEL. Replacing that gear is a very time involved job. The sensor isn't as bad.

 

The first thing I'd do is make sure the speedo cable is plugged into the cluster okay. After that though...

 

X2, this is probably what happened. It is somewhat common.

1998 doesnt have a cable, its all electronic.

 

It sounds like you lost the Vehical Speed Sensor. Maybe you hit something and damaged the harness.

 

nipper

1998 doesnt have a cable, its all electronic.

 

It sounds like you lost the Vehical Speed Sensor. Maybe you hit something and damaged the harness.

 

nipper

I didn't know that. Good thing other people know more things than I do about these newer cars

Hopefully your mechanic will pull the vss out of the tranny and check to see if the gear in the tranny spins by hand first. It shouldn't. Many vss have been changed when the real problem was with the internal gear.

 

As far as the smell. My guess is the engine ran lean with no speed input, so the cat caused the exhaust to smell funny. Kinda hard to say over the internet though.

 

Alternator? Very plausable, but you should be having starting problems by now if that were the case.

 

Good luck! Let us know how it turned out.

Loss of one VSS can certainly cause the speedometer to stop reading, so I'm not dismissing the possibility. However, that doesn't typically cause the stalling that was reported by Bmm001. As to the burning smell, as McDave said, "Kinda hard to say over the internet".

 

Alternators can fail in various ways, and they don't always light the dash charge and brake warning lamps. The '98 Legacy had a recall for defective alternators -- see the second entry at http://www.automallusa.net/1998/subaru/legacy/recalls.html . Sometimes the problem is intermittent before complete failure, and depending on the exact failure mode can take out other circuits. It still might be worthwhile having the charging system looked at.

I'll keep everyone posted as soon as I hear something from my dad. I believe the alternator was replaced way back when it was new due to Subaru's alternator recall program.

 

Thanks for all the input so far! I'll be interested to hear if the CEL and the shutting off and the speedo not working are all completely related, but it sorta sounds like that's a good possibility.

 

Brian M.

I did some more checking on this problem. There are actually 2 speed sensors on the car. The one with the internal gear that operates the speedometer is in the transaxle, the other one in the tranny section sends the signal to the ecm and is triggered by magnets inside the tranny.

 

Have the mechanic scan the ecm. It's likely he will be getting a signal to the ecm, but not to the speedo, of course. Techs report the sensors 'never' fail and apparently the transaxle gear doesn't fail like the type that has the gear in the tranny. Still worth checking though. The most likely cause is the speedo head in the dash. Very common failure.

 

But then that doesn't explain the stalling either.

I did some more checking on this problem. There are actually 2 speed sensors on the car. The one with the internal gear that operates the speedometer is in the transaxle, the other one in the tranny section sends the signal to the ecm and is triggered by magnets inside the tranny.

 

Have the mechanic scan the ecm. It's likely he will be getting a signal to the ecm, but not to the speedo, of course. Techs report the sensors 'never' fail and apparently the transaxle gear doesn't fail like the type that has the gear in the tranny. Still worth checking though. The most likely cause is the speedo head in the dash. Very common failure.

 

But then that doesn't explain the stalling either.

 

Keep checking.

 

The AUTO has two sensors, and in a 1998 they are both in the transmission. The reason for two is for the the computer to properly operate the AWD clutch pack. In pre OBD2 the 2nd sensor is part of the spedo head.

 

This is a manual which uses a non-electronic Viscous coupling (in this year) to operate the awd.

 

Without the VSS operating, the car is in limp mode, so its really hard to diagnose anything properly untill its fixed.

 

nipper

Don't have much of an update, but a few questions/notes:

 

So they wouldn't be able to pull the check engine code if it's in limp mode?

 

Didn't get very far today. My mom had it up and they talked to her about a bunch of stuff but couldn't give a definitive answer, they needed to do some research... only one of them was there today so he was a bit swamped.

 

She had no idea what he was talking about so she couldn't really repeat it to me or my dad. He can go off on tangents, and I'm the only one that usually is interested/understands what he's talking about ha ha.

 

She said they plugged it into something (possibly trying to read the code), but that's about all she could say other than they said it should be OK to drive (even though we won't much until we get some answers). She remarked that it seems like the trip meter doesn't change (along with the speedo not moving) but the odometer does. It also shut off on her again on the way home from the garage.

 

One of us will call tomorrow to see what they're talking about and see how we need to proceed.

 

Brian

They should be pulling codes if the CEL is on no matter what condition the car is in.

 

Limp home mode is just that. It will get the car back "home" (repair shop) under its own power so you wont get stranded. Under limp mode the engine RPM be limited. If this was an automatic you would be limited to 50 mph max.

 

 

The stalling may or not be related, but its sort of like treating someone for a hang nail and chest pains at the same time, when you really need to worry about the chest pains first.

 

nipper

I agree, I want more of an explanation and maybe it's there and we're just not getting it if they were talking over my mom's head. We're going to call tomorrow, and if they don't know I'm calling the place where I bought my car from, who also specializes in Subarus.

Lets try this for a 3rd time (white screen of death)

 

Has anyone looked under the car just to see if there are any damaged wires ?

 

 

nipper

Like I said, I do not know what was and was not done/looked at until I call them tomorrow.

 

Brian

The CEL code was for the Vehicle Speed sensor. They're going to check it and swap out the sensor on the transmission on Thursday to see if that cures it. If not, they think it could have something to do with a second sensor (my dad couldn't remember what they called it) on/near the speedometer head.

 

The mechanic said they've noticed more issues with '99 and newer sensors malfunctioning, something about them being a different part or design. Said there's a slight possibility that our '98 may have this design depending on when it was built in '98. If it has something to do with the speedometer area sensor we'd need a new one.

 

Question:

 

Is the car shutting off when slowing down caused by the faulty VSS? I drove it tonight, and rolling up to a stop with the clutch depressed, the RPM's would drop below 500, and then suddenly the car is off. No shudder, stutter, no nothing, it's just off. I duplicated this event 3 times. But it doesn't do it EVERY stop. Also didn't seem to do it if the car was in neutral and I came to a stop.

 

It also did it once with the clutch depressed as I was slowing to round a corner.

 

Brian

How does it idle while it's sitting still? Will it idle back up when you put a load on it like turning the headlights and a/c on all at once?

 

If it does recover from the load quickly, I believe all is well and fixing the speedometer should fix it.

 

I believe while rolling along, a correct speed input would lead to the ecu increasing the rpms enough to compensate for sudden loads from the power steering, among others.

 

But I've been wrong before!

But I've been wrong before!

 

It seems to idle normally, around 750 RPM or so. Runs and drives fine. My dad will be driving it to work tomorrow morning very early so he'll have the headlights on. I'll have him test w/ the A/C as well.

 

By the way, the CEL turned off after one of the re-starts (didn't mention that before), but I bet it will be back on. They reset it at the shop, and after 10 minutes or so of driving home, it came back on for my dad.

 

Brian

Sorry Nipper. I didn't mean to leave you speechless.

Good news. It was just the speed sensor on the transmission. They popped a used one on and for a grand total of $50 and we're set!

 

Brian

Good news. It was just the speed sensor on the transmission. They popped a used one on and for a grand total of $50 and we're set!

 

Brian

Crap, nipper was right again!

 

PS Glad you got it fixed cheap!

That's the nice thing about having a shop that will try an easy, sensible fix before just throwing parts and $$ at a problem. Was there a friendly wager? Ha ha.

 

Brian