Speedo And Tach Stop Working Why?

[Lexmanic]

Drove my 97 LS today & both the tach and the speedo didn't work when I started to move. The Tach after a few moments began to work BUT the speedo is still not working. Can anyone offer an explanation as to why this has happened.?

[marvs]

I can't be certain on the later cars (mine's a 93), but it sounds a lot like the 'sticky needles' issue that I had with my speedo and tacho.

It's probably due to the needle lubricant leaking onto the needle stopper behind the face, which causes part of the needle to stick to it.

See these couple of posts for more info (I've linked to the individual posts, but from there you can click the link in the top right to see the whole thread):

Sticky Needles 1

Sticky Needles 2

If you do try to fix this yourself, try a pipe cleaner rather than a cotton bud - I found a cotton bud too 'fat' and hard to get into the back of the mechanism. I soaked it in isopropyl alcohol. Then added a bit of WD40 for good measure!

Also, be VERY careful not to pull the needle around too much. I think I must have done something to the spring in the back of my speedo needle, which means that now when I am not moving my speedo sometimes reads ~30mph! It fixes itself as soon as the car moves though...

[Titch LS]

Could be the symptom of a failed or failing Speed Sensor. Speedo's pack up when the sensor fails. Seems strange to me that both needles have suddenly become sticky at the same time though. My money is on the sensor. Are your gears shifting as smoothly as usual? Poorer shifting is another sign, as the Ecu lacks imput from the speed sensor to time the gearchanges nicely. If it all checks out o.k. you better get the pipe cleaners out instead and clean those needles.

[steve2006]

Do the dash thump test 1st, does this bring them back to life?

[marvs]

^^ Good idea. Although having said that, whacking the dash never dislodged my needles.

Maybe I'm just too weedy! Or my sticky needles were just too sticky!

[Lexmanic]

The whack method seems to have worked

[marvs]

That's a very good sign that the problem is the leaky lubricant causing the needles to stick.