99 wagon speedometer works when it wants to, HELP

[thecougfan]

I have a 1999 subaru legacy wagon brighton edition. The probelm is the speedometer only works when it wants to, going on and off at will with no real pattern to its madness. The only thing that seems to work occasionally is to press the trip odometer reset a few times and sometimes the speedometer will start working again.
In attempting to fix the problem we have replaced the sending unit (attached to the transmission and sends the signal to the dash unit), that did not work. We then replaced the entire gauge cluster including the speedometer, this did not work. We checked the continuity of the wire running from the sending unit to the speedometer and it was fine, obviously the speedometer still didnt work...
Has anyone else had this problem or maybe just have any idea as to what the problem could be?

[SUBARU_TECH]

first if you can tell me which speed sensor you you replaced.is it the single unit that is on the passenger side of trans bell housing.or did you replace the speed sensor harness that has 2 sensors.how did you check the wire to the speedo head.the must be 2 volts or more with all wheels of the ground and speed over 25 mph.

[tanwagonman]

I have a 99 legacy wagon with exactly the same issue. Tac works fine, but speedo is intermitant. Sometimes it works, sometimes it doesn't. Have you solved the problem yet? Have you done the attempted repairs yourself, or did the dealer try to fix the problem. I'm trying to wait until it completely stops working before I take it in to get fixed, that way I'll know that the problem it solved.

[SUBARU_TECH]

there is no one fix.you must test each componet to find the cause.the best way to check this is to pull the meter assembly out.on the back center of the meter assembly is a 5 pin connector.the center black wire is the signal wire.attach a dvom,digital volt ohm meter , back probe that wire with a striaght pin and attach the red lead from meter to it.black lead of meter to good ground.just lay the meter back and in test drive.when the fault happens see if you have 4volts or more when the car is traveling 12mph or better.

[tanwagonman]

Thanks, sounds like a fairly simple test. Can you give me a couple of pointers at removing the meter assembly? I took a look, and there are 4 philips screws that hold the assembly cowling in place. Is it as simple as taking them out to access the assembly, or do I have to do a major disassembly of the dash?

I don't have a service manual for the car. I've seen a few places on ebay and the web as well as the standard Haynes. Any reccomendations?

http://www.datamanuals.net/subaru_comp.htm

[SUBARU_TECH]

yes just the 4 screws for the bezel.then you must pull the bezel out abit then disconnect each harness switch for that bezel.there is then 4 more screws for the meter assembly.

[tanwagonman]

Finally took the speedo head out, added a wire to the back of the connector, put the speedo head back in and did the tests. AC voltage measured was over 4.5 Volts when driving, but speedo didn't work. When the speedo was working the voltage was the same. Tried re-soldering all the connections on the back of the speedo head, but did not resolve the issue.

I had a fight with Subaru Canada trying to get them to either give me the head for free, or give me a break on the price, but they were unwilling to recognize this as a manufacturing defect despite the numerous examples of this failure on a componenet that I expected to last the life of the car.

I've ordered a replacement speedo from the U.S. for $112.00 as the Canadian dealer wanted $250+tax for the unit.

Was able to download the entire service manual for the car from the subaru tech web site.

Shoud have the new head next week, so I'll repost after I've installed the unit.

[thecougfan]

So i finally broke down and took the subaru to a subaru repair shop. He said it needed a new speedometer head. Having replaced the cluster 3 times (which includes the speedometer head) I told him thanks but no thanks and payed him his money for doing very little. Alas I decided it couldnt hurt to try this crazy idea so we purchased a brand new speedometer head, and what do you know it works and has for a month straight.

[bozeorbust]

I also have a 99 Legacy Brighton Wagon that has the same intermittent speedo problem. It started as an infrequent occurence but now has become more and more the case. Early on playing with the wiper controls seemed to start up the speedometer again. Now this does not seem to work very often. I took the instrument cluster out and made sure the speedometer head screws were tight and that all the connectors were seated. I also pulled the vehicle speed sensor (VSS 2) connector and visually checked the wires for problems. Seemed to be OK. This seemed to help temporarily but the problem came back quickly. I'm not sure what to replace first the speedometer head or the speed sensor. Any suggestions?

[SUBARU_TECH]

i have replaced just as many speed sensors as speedo heads.without testing its a gamble to guess.

[bozeorbust]

Thanks for your reply Subaru Tech! I thought the speed sensor also gave input to the ECM to adjust timing and fuel mix. If the defective part was the sensor would I notice a difference in engine performance when the speedo wasn't working? Also, what's the chance the problem is in the wiring harness?

[SUBARU_TECH]

no you wont see a difference in performance.

[mrhildeb]

I own a 99 Legacy Outback Limited Edition and have begun experiencing the exact same problem as you al have described. Have any of you come to any conclusions? The one thing that I find interesting with my case is that the cruise still contiues to work, which means that speed is being sensed somewhere. Have any of you had these same symptoms?

Also, why are there two different speed sensors

[lophius]

I've had the same problem for about 2 years now. The speedo works intermittently. The cruise control always works - even when the speedo does not. My wife discovered that toggling the door locks (electric) will cause the speedo to start working about half the cases. I've also tried the window and sun roof, but that approach is nowhere near as dependable as the door locks.

Does the speedo and cruise control use different speed sensors, or does the fact that the cruise always works rules out the speed sensor as a possible culprit?

Thanks.

[jarbadgolfer]

1999 Legacy Outback. Same problem.

Thanks to SUBARU TECH for the diagnostic tip. It's easy to do.

When the speedo is working, the DVM measures only 2.4 V DC and 2.7 V AC at speed, not the 4 V that SUBARU TECH says should be there. Is that already an indication that one of the sensors, not the head, is faulty? I will post again when I can get measurements when the speedo is not working.

Also, should I be measuring AC or DC? tanwagonman says AC, I'm just double-checking.