# 98 Jetta Speedometer & Tachometer not working - already replaced cluster



## timeOday (Sep 28, 2012)

My speedo and tach were cutting out intermittently on my 98 Jetta GLX for a while, and now work never or almost never. So I bought a new cluster, but it acts exactly the same. The "new" cluster is used, but the seller assures me it was working. (But said I might need to 'reprogram' it.) Both clusters are at least getting power (they show mileage etc) but the tach needle is dead still while the speedo just tremors a tiny bit. I don't think it's the VSS since the tach is affected, not just the speedo.

What else could it be? How would I go about testing the harness (shudder).

Possibly related, some little electric motor is sometimes not shutting off even when the key is out of the ignition, and ran the battery dead - but it only happened once. Thinking it was the smog pump I removed the relay but still heard the sound - but perhaps I am confused because what the Bentley manual shows as the secondary air injector relay is sold as a radiator fan relay.

Other longer-standing issues that probably aren't related - the cruise control and power locks don't work (I assumed this was the vacuum system), one power window doesn't work (have replaced multiple window regulators in the car and just haven't bothered), the ABS light is stuck on.


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## lucatso (Jul 20, 2008)

*so weird..*

my speedo/tach have quit working also! around the same time as yours and after reading it looks like our VWs must have been built one after another at the same factory(mine is a GL)! i am having some of the same problems as you! my speedo/tach started working intermittently and has now completely stopped working. the speedo just violently twitches at 0mph while the tach is still. the odometer, clock, engine temp and fuel gauge still work properly. have no idea why. 

my cruise control doesn't work either. apparently there are no relays or fuses but a cruise control module that is ridiculously expensive from VW. junkyard would probably do but i just haven't gotten around to it yet. i did replace the turn/cruise lever/switch and that didn't fix the problem. i replaced that when i was trying to chase a weird electrical issue with my turn/tail/brake lights. that ended up being a burnt out electrical connector on the pass. side tail that i over looked. my power windows work only because I've replaced all four window motors/regs in the five years I've owned the vehicle. my door locks still work, lucky me. 

1999 Jetta GL MKIII
2.0L manual trans
130,000


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## lucatso (Jul 20, 2008)

*ANSWER(hopefully)*

picked this from adrian in the topix.com vw auto forum: 

GOT IT!!!!!

Steeper motor (the one that moves the needle). One of the gear was broken and would slip when the needle got to zero, puzzling the cluster electronics and disabling the other gauge. 

Thats why one of the needles would keed trying to reach zero and the other would be quiet. 

When the car is cold, the gear have just enough grip to hold the steeper motor shaft during the zeroing.

thank you adrian! hope this works!


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## prasina2 (Apr 10, 2003)

might want to look through this too :thumbup:

http://forums.vwvortex.com/showthread.php?4805351-Why-our-clusters-go-bad-Microscope-photos-inside


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## timeOday (Sep 28, 2012)

That is really interesting that a broken speedo might confuse the electronics into disabling the tach (or vice versa). 

I don't think a stripped gear in the speedo needle server, or bad solder joints in the cluster is my problem, since, as I mentioned, I already replaced the cluster and it didn't help.

I had thought it was probably not the vehicle speed sensor (VSS) because, I figured, that would affect the speedo but not the tach. But since they are apparently linked through the computer chip, I am going to go at the VSS again.


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## timeOday (Sep 28, 2012)

Oh yeah, I just remembered how I convinced myself why it "could't" be the VSS. Since the tachometer works even with the car sitting still, when the VSS isn't sending any signal, shouldn't the tach still work even if the VSS is broken?


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## timeOday (Sep 28, 2012)

timeOday said:


> ...since the tachometer works even with the car sitting still...


I should have said, "normal works..." Mine currently doesn't work at all.


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## snowmanii (Mar 4, 2011)

*speedo*

timeoday

The motor you said ran your battery dead may be the vacuum motor. It used to happen to me at the same time my locks quit working. I repaired a cracked tube going from the middle pillar to the rear left door and locks work again.

My issue with speedo is different than yours. Mine will work for a while, but then quit to zero but tach works all the time without fail. I can make speedo needle come up momentarily by smacking dash and sometimes it even comes on by itself when i'm in a turn.


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## hintzy64 (Jan 23, 2009)

My '97 Jetta started doing the same thing today but backwards, my tach tremors and the speedo sits at zero. The issue started last week with the tach twitching violently for a few seconds every time the car was turned on or off, but it would work normally after a few seconds (and the car was always stopped, so I couldn't tell if the speedo was affected). Then a few days ago it magically went away and everything was fine, but today both gauges are dead. All other instruments and dash lights are working. (well...the airbag light flickers sometimes, but it's done that for years)

I pulled out my wiring diagrams and it looks like the connections go alternator > fuse/relay box > tach > fuse/relay box > VSS > ground. (Speedo is not on the diagram.) So my thoughts were to check the alternator and VSS. I'm already suspicious of my alternator since the car randomly stalled while sitting at a light a few weeks ago, but it tested out fine at the time. Could a problem with the alternator (or it's grounding strap) create a voltage at the tach sense cable and knock out both gauges? Or similarly with the VSS? I might also try hooking up my code reader while driving to see if good RPM and speed readings are getting to the computer. I'd be fine if one gauge or the other died, but losing both sucks...

Add this to my long list of electrical woes! My cruise control has never worked, my alarm went berserk a few years ago and ended up getting bypassed, my airbag light flickers, my temp gauge sometimes jumps erratically, I've replaced window regulators/motors several times (and another is dead now), I've had door switches and power locks short out in the rain, a solenoid in the SAI system died last year, and I've had my reverse lights get stuck on. Also, the paint on my hood is shot and body trim is starting to fall apart. But otherwise, it's tip top!


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## hintzy64 (Jan 23, 2009)

Wait...the odometer/trip is counting, so that suggests the VSS is fine. Hmm.


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## hintzy64 (Jan 23, 2009)

Aaaaand today it works fine. :screwy:

EDIT: Just kidding. Dead again. :banghead:


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## rockystar (Jul 23, 2011)

The motors that run the speedo and the tachometer are wired in series. If one is malfunctioning neither will work. The vibrating needle is common problem and usually indicates the motor has gone bad as mentioned earlier, which means the other needle does nothing. I understand you tried a replacement but even if they assured u it works u should try both of them in a different mk3 to verify. The stepper motors going bad is really common and their really easy to damage. Like if your taking the needles off and u pull too hard they can be broken.


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## hintzy64 (Jan 23, 2009)

rockystar said:


> The motors that run the speedo and the tachometer are wired in series.


 Good job, VW. :thumbup:

:facepalm:


EDIT: Actually, you've given me an idea. From everything I've read/heard so far, it looked like my problem was probably failing solder joints or printed paths on the circuit board, which would be highly annoying to try to fix. My dad suggested I hit up the junkyard for a new instrument cluster, but I could easily run into the same problem with any used part. But my gauges don't start and stop working randomly while driving; if they come on when I start the car, they work, and if they don't, they don't. That seems more consistent with a bad stepper motor. And it'll be the one on the tach, since that's the twitchy one in my case. Still a delicate operation, but at least it narrows down the fix to one component instead of searching the board for bad solder joints.


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## Toaster Oven (Jan 1, 2017)

*No tach no speedo 2000 cabrio step motor*

2000 Cabrio OK LOST TACH AND SPEEDO. every other key cycle... WAS TACH STEPER MOTOR. That dude nailed it,, he is right about the tachometer, it takes out speedo. Same thing I was thinking this summer I did OHM out the two motors on the circuit card/cluster.. could not get a reading. I de soldered the tach motor. reinstalled cluster but did not replace the motor. my Speedo works 100% time since July. Does anybody know where to locate a new step motor oscillator motor or what ever I might buy one.


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