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Speedometer sensor location


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43 replies to this topic

#1 rumlow

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Posted 21 November 2003 - 09:20 AM

The speedometer on my 99 Legacy Wagon 5-speed has
been intermittently failing. No warning lights come on. I mostly drive in city so I have not tried the cruise control to see if it works when this happens. I want to check the wiring but can't
locate the sensor. I have posted a picture at
http://www.kscon.com/subypass.jpg of the passenger side of the engine. The differential dipstick is in about the center of the picture. If somebody could point out the sensor I would greatlt appreciate it.

#2 99obw

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Posted 21 November 2003 - 12:53 PM

I have had an intermittent speedometer on our 99 outback with auto tranny for quite a while. I have been too lazy to fix it.

Our cruise works regardless of whether the speedometer is working.

Please try something for me...When the speedometer quits working hit the front windshield wiper button several times very quickly. Does it come back on? Works almost every time on ours, which makes me think it is the speedometer head or a bad ground.

I think the sensor(s) are further back on the top of the tranny. I can look in the FSM and let you know if nobody else chimes in.

#3 slideways

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Posted 21 November 2003 - 01:56 PM

My 93 legacy is cable operated, and I do not know if they have changed it on the newer models. Anyways, if it is cable operated, it comes out of the transmission on that side, just furthur back.

#4 Legacy777

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Posted 21 November 2003 - 02:13 PM

The newer models the sensor is on the transmission.

The older ones....the sensor is actually in the combination meter and there is a cable that comes up from the tranny to it.

#5 mtsmiths

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Posted 21 November 2003 - 02:54 PM

The speedo on my '87 waps all the way over the 130 now and then. Doesn't affect the odometer count. It always stayes there until the car comes to a stop. Next time it moves it may settle down to normal, or go back up to hyperspeed again.

My indy mechanic says it's a bad seal on the tranny letting gear lube up the shaft, and is too much trouble to fix. If so, I don't know why it comes and goes, it's not a function of temperature or miles driven.

Mysterious.

#6 Hondasucks

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Posted 21 November 2003 - 04:51 PM

If I had to guess, I'd say look on the transaxle where the speedometer cable would be if it had one, that is usually where the speed sensor is located. I'd check the wiring and whatnot before I replaced the sensor though, those can be expensive!

Also, is it still under warranty?

#7 alias20035

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Posted 22 November 2003 - 07:06 AM

On the cable (mechanical) speedometer, there are two vehicle speed sensors (VSS), one for the cruise control, and one for the ECU (and maybe the ECU will use the cruise one as backup). These VSS sensors are built into the speedometer gauge (dash).

The cable directly turns the odometer gears, and also a magnetic wheel which will pull the speedometer needle to the correct speed (hopefully). If the spring which resists the pull of the magnetic wheel is defective, or there is a problem with the speedomoter needle spindle, the speed reading will be erratic.

This magnetic wheel also trips two sensors which generate one electical pulse for each speedometer cable rotation, these are the two vehicle speed sensors.

The VSS system works in an identical fashion to the bicycle computer with a magnet on the front wheel spokes and a sensor on the frame.

The newer Subaru's are electronic and have no speedometer cable and I think your 99 Impreza falls into this category. A sensor within the transmission generates a pulse which is sent to the speedometer/odometer head, ECU and cruise control. I don't know if the pulses go to the cluster firstand then to the ECU (which would allow for a similar wiring structure as the speedometer cable setup), it doesn't matter though.

As far as I can tell the speedometer needle is still an analog system which just moves to the correct speed based on the frequency of the electrical pulses from the VSS. The odometer simply counts the pulses, as each pulse equals a set distance.

If you have a LCD digital odometer, you should have the VSS built into the transmission, otherwise you should have a cable to the cluster which contains the two VSS's. It might still be possible to have an LCD odometer driven off the VSS within the speedometer cluster which uses to old style cable.

In any case if your ECU is not complaining about a dead VSS (check engine light) and your cruise control is working, the problem lies with the mechanical components of the speedometer. You will need to find one at a scrapyard. If you know what you are doing it is possible to transplant your original mechanical odometer (if working) to the replacement speedometer gauge, so your indicated mileage will not be affected. If you have the digital LCD odometer, these units can not be disassembled (they break), so it will have to be programed with your mileage, or you will have to register the mileage change with your state licensing agency (if required by law). There are shops with odometer programmers, just take the replacement odomter to one of these shops while your original odometer is still in place and working and they will set it to match, they may insist that they install the odometer though but it is less than an hours labour (25-40 minutes).

You should be able to tell whether you have a speedometer cable quite easily. Behind the dipstick (between 12-18 inchs if I recall) a cable will come straight up out of the upper passenger's side of the transmission. If this is a thick (pencil size) cable which is quite stiff which makes its way to the firewall heading straight at the speedometer it is the older cable based unit. If there are flexible wires and an electric harness on passanger's side of the transmission behind the dipstick, it is the newer model with transmission integrated VSS and electronic speedometer. The wiring harness on the other side (driver's) is the reverse light activation switch.

The warranty on this item is 3yr/36000 (bumper to bumper) so it would not be covered... I think a VSS failure is covered to 5yr/60000 though, but not the speedometer.

#8 Syd

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Posted 23 November 2003 - 10:15 AM

If eventually you need a new speedometer, I have a whole cluster from a '95 legacy. bought it from ebay for the tach, which I installed in my '97 legacy.

Syd

#9 rumlow

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Posted 02 December 2003 - 09:22 AM

I am still having this problem, but believe it or not the first reply was the most helpful. Whenever the speedo fails, a light tap on the right stalk (windshield spritzer, etc.) solves the problem. Sometimes its one tap, sometimes quite a few, but it has worked to far. A buddy who is a car repair enthusiast but no a Suby owner thinks that there is a switch module under the dash that might need some contact cleaned. maybe we'll work on it come spring -- right now a long way away.

Again, thanks for your help.

#10 PAezb

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Posted 02 December 2003 - 10:55 AM

rumlow,

I'm sorry this won't help you directly but it is topic thread related. To help anyone with a newer Sube with an auto, I've attached a pic showing it's VSS (vehicle speed sensor) location, passenger side just forward of the diff dip stick (somewhat hidden under the white connector in the pic). It has a 2-wire connector. I've placed the old VSS in front of the new installed one to show what it looks like. Not sure if all model years later than mine will be the same - 96 OBW/auto 2.5

In my case, the bad VSS was causing the speedo needle to jump wildly when below 30mph, then would act normal above 30mph. Also affected the tranny's shifts. Other speedometer problems could be caused by another VSS that's located in the speedometer head itself - a buffer circuit that the ECU uses. Fortunately, my problem was the cheaper and easier fix of the 2 VSS's.

Hope this helps someone else.

#11 PAezb

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Posted 02 December 2003 - 11:18 AM

A closer view....

#12 99obw

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Posted 02 December 2003 - 12:15 PM

Originally posted by rumlow
I am still having this problem, but believe it or not the first reply was the most helpful. Whenever the speedo fails, a light tap on the right stalk (windshield spritzer, etc.) solves the problem. Sometimes its one tap, sometimes quite a few, but it has worked to far. A buddy who is a car repair enthusiast but no a Suby owner thinks that there is a switch module under the dash that might need some contact cleaned. maybe we'll work on it come spring -- right now a long way away.

Again, thanks for your help.



It's amazing to me that someone else is having the speedometer behave in exactly the same way.

I have a speedometer head for the car. I have no idea if it will actually fix the problem. I can put it in ASAP and let you know.

Can your friend elaborate on what he thinks the problem is? All help is welcome.

#13 99obw

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Posted 30 December 2003 - 10:11 PM

Well, ASAP was a couple of days ago. Went in fairly easily. Works great so far.

Hey!! We have a brand new car with 9 miles on it!! :D

I will try and report back as the miles accumulate and let everyone know if the intermittent failures are gone.

(Fingers crossed)

#14 corsair

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Posted 31 December 2003 - 03:15 PM

I have a 1999 Subary Legacy 4dr. sedan 2.2 with the intermittent speedo problem. It seems to work more frequently than not, but I have seen that when I reset the trip odometer to zero and hold the button down, that the speedo will STOP, and then later at some random time start working.

As for the pictures that have been posted here, I can see exactly on my car (passenger side) where the speed sensor would appear above the right side CV boot, BUT the sensor is not located there on my 2.2 lit. engine. Can someone tell me whether these pictures are from a 2.5 lit. Outback? The speedo speed sensor location might different on the 2.2 engine. I have seen previous posts on this same issue in alt.autos.subaru, but I have not yet seen a solution. There are no NHTSA Recalls either (yet):

http://www.nhtsa.dot.../cars/problems/

#15 Tooth

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Posted 13 February 2004 - 12:55 PM

I've had the exact same speedo problem for a few months now.

Just like the others, the speedo works intermittently, but if its not functioning -- turning on the windshield wipers and/or tapping the windshield wiper button seems to make the speedo start working again.

Any new ideas on this subject or permanent corrective measures?

#16 99obw

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Posted 13 February 2004 - 01:22 PM

I have been meaning to report back on this topic.

Just about 3200 miles on the new speedo and NEVER a failure!!!

Replacing the speedo head seems to have fixed it. YMMV

#17 corsair

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Posted 14 February 2004 - 11:40 AM

Yeah I called Subaru on this issue and they say that there is no recall, in spite of the fact that many people seem to have this problem. How much were you charged to have the speedo head replaced (probably not under factory warranty). Doesn't the whole instrument cluster have to be removed? How long did the job actually take (if you know) ?

#18 Tooth

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Posted 27 May 2004 - 09:05 AM

In any case if your ECU is not complaining about a dead VSS (check engine light) and your cruise control is working, the problem lies with the mechanical components of the speedometer. You will need to find one at a scrapyard. If you know what you are doing it is possible to transplant your original mechanical odometer (if working) to the replacement speedometer gauge, so your indicated mileage will not be affected.


I've finally decided to do something about my speedometer that has been working intermittently for the last several months.

Recently had a Subaru shop check out the electronic components and they indicated that a speed signal is being sent to the speedometer, but is not registering on the instument panel. They recommended replacing the cluster.

I got an instrument cluster from the junkyard, but now I need some pointers on how to transplant the original odometer to the replacement instument cluster (so that I don't have to flag the the odometer reading).

I've already disassembled the original instrument cluster and removed the speedometer gauge, but there doesn't seem to be an easy way to separate the odometer from the speedometer needle and faceplate.

Any help?

#19 corsair

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Posted 27 May 2004 - 08:46 PM

I've finally decided to do something about my speedometer that has been working intermittently for the last several months.

Recently had a Subaru shop check out the electronic components and they indicated that a speed signal is being sent to the speedometer, but is not registering on the instument panel. They recommended replacing the cluster.

I got an instrument cluster from the junkyard, but now I need some pointers on how to transplant the original odometer to the replacement instument cluster (so that I don't have to flag the the odometer reading).

I've already disassembled the original instrument cluster and removed the speedometer gauge, but there doesn't seem to be an easy way to separate the odometer from the speedometer needle and faceplate.

Any help?

========================================================
I checked with a Subaru stealership who says that there is a sensor INSIDE the speedo head which receives impulses from the VSS (I have a 1999). This (the speedo head) is likely the problem rather than the cluster itself. Putting the OLD speedo head into another cluster will likely not solve the problem. What needs to be replaced is the speedo head. I have an ODBII scanner and can tell you that this speedo problem does NOT set an error code into memory (since I have read no error codes on my car). If you go to a stealership, they will charge you an arm & leg to replace the speedo head and will recalibrate the speedo accordingly.

I don't have an exploded diagram of the speedo cluster & head. Can you post a picture (JPG) of the back of your junkyard cluster with the head separated from the cluster?? Does the speedo head have any electronics or any electronic connections to the cluster??? If someone has a PDF with an exploded view of the cluster, can you post it for the rest of us ??? I have looked high and low for a paper manual for my 99 Legacy, but have only been able to get an update manual (about 2.5'' thick of looseleaf pages) but which has no diagrams of the instrument cluster.

#20 homeden

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Posted 30 June 2004 - 10:04 PM

========================================================
I checked with a Subaru stealership who says that there is a sensor INSIDE the speedo head which receives impulses from the VSS (I have a 1999).

I don't have an exploded diagram of the speedo cluster & head. Can you post a picture (JPG) of the back of your junkyard cluster with the head separated from the cluster?? Does the speedo head have any electronics or any electronic connections to the cluster??? If someone has a PDF with an exploded view of the cluster, can you post it for the rest of us ??? I have looked high and low for a paper manual for my 99 Legacy, but have only been able to get an update manual (about 2.5'' thick of looseleaf pages) but which has no diagrams of the instrument cluster.


Any luck with getting a pdf?

I've got a 99 OBW as well and the speedo has been working on and off over the past couple of months. It usually stops working when I backup and then comes back to life 10 - 20 minutes later in forward. Weird.

Looking at all the other similar complaints about their speedos failing however doesn't seem to point to any one particular solution. But I was hoping to see if anyone followed up with your asking for a exploded view of the cluster.

#21 corsair

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Posted 04 July 2004 - 10:25 PM

Any luck with getting a pdf?

I've got a 99 OBW as well and the speedo has been working on and off over the past couple of months. It usually stops working when I backup and then comes back to life 10 - 20 minutes later in forward. Weird.

Looking at all the other similar complaints about their speedos failing however doesn't seem to point to any one particular solution. But I was hoping to see if anyone followed up with your asking for a exploded view of the cluster.

Nope, I didn't get any PDF or other diagrams, so I'm still in the dark about this. There are really only two possibilities though, the VSS sensor which sends the impulses, or the speedo element in the instrument cluster which receives the impulses. The only way to know, is the check if the impulses are being reliably transmitted, and if so, the only thing left is the speedo component in the cluster which receives the impulses. This is probably the same troubleshooting logic that the stealership will use if you are willling to pay to have the dealer do it. I'm not motivated to find out which one it is before I reach 100k since I have an extended warranty. I'll post the answer here in the next year (or so) when my warranty is ready to run out.

#22 homeden

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Posted 05 July 2004 - 06:14 PM

Nope, I didn't get any PDF or other diagrams, so I'm still in the dark about this...The only way to know, is the check if the impulses are being reliably transmitted, and if so, the only thing left is the speedo component in the cluster which receives the impulses. This is probably the same troubleshooting logic that the stealership will use if you are willling to pay to have the dealer do it. I'll post the answer here in the next year (or so) when my warranty is ready to run out.


Thanks for the info. I tried the other suggestion of hitting the windshield wipper spray button 1 - 2 times and that worked! So I suspect its the speedo coupling that needs replacing.

#23 99obw

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Posted 05 July 2004 - 06:22 PM

I see some activity in this thread so I will post an update. About 15k miles on the new speedo head and never a failure. Sure worked for me!

BTW the speedo head part number for a 99obw with 2.5 and auto tranny is 85020AC330.

#24 corsair

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Posted 12 July 2004 - 11:15 PM

I see some activity in this thread so I will post an update. About 15k miles on the new speedo head and never a failure. Sure worked for me!

BTW the speedo head part number for a 99obw with 2.5 and auto tranny is 85020AC330.


Thank you very much !

#25 Rockman

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Posted 27 September 2004 - 04:19 PM

I see some activity in this thread so I will post an update. About 15k miles on the new speedo head and never a failure. Sure worked for me!

BTW the speedo head part number for a 99obw with 2.5 and auto tranny is 85020AC330.


Looks like I've got the same problem on my 99 Outback. No error code is sent to memory on a diagnostic check. If the intermittent failure is a result of a bad VSS would that send a code? I'll have to try the windshield wiper technique-that seems to point to the speedo head. Great info!

How hard was it to get at the instrument cluster to replace the speedo head?




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