Ive been having a problem with the tachometer it doesn't take any reading it just goes up. When I turn the car off it goes back to zero and then Jumps up and down. I'm thinking it wiring or a ground but I'm lost. I washed out the engine bay I know don't tell at me and it started the next day. Any help would be great thank you!!

http://www.youtube.com/watch?v=WW4dAgGHGWc&feature=youtube_gdata_player


I did find out that when I open the door to the car it jumps also here's a video of it


http://www.youtube.com/watch?v=yOcKypiUNmU&feature=youtube_gdata_player

 

I also found that it jumps when I open the door... Odd

Tachometer prob cont. - YouTube

 

Def looks like an internal problem with the cluster to me. You could VAGCOM the engine to make sure you are getting good RPM readings, but it looks like you need a new cluster.

 

If it was internal why would it respond to the door opening and closing? I've hooked it up already and I do have good rpm readings

 

Because the cluster has a signal that says whether the doors are open or not.. If a cluster has failed internally, pretty much anything can happen, anything. Here's a couple of things you can try but it probably won't help: VAG COM the instrument cluster and see if there are codes, also check the measuring blocks and see if there is one for RPM (I cant remember if there is one for RPM or not). You can also do an output test and do a needle sweep of the needles. If the RPM needle doesnt sweep correctly then its positively the cluster, if it does sweep correctly it could still be the cluster (and it probably is based on how it acts), or an improper connection of the RPM signal to the cluster, and maybe shorted to the door open wire (but I really doubt it, when the cluster is off I dont think the RPM needle should move at all no matter what the status of the door, or the status of the RPM's, i.e. turn your car off in a safe place while it is moving, all of the needles will die).

 

Ya it moves while the car is off it like ticks up and down I'll try the vag com stuff too

 

Hmm.... Just started magically working again today! Well I left my interior dash and those lights on for an hour last night came back out the tach was working and still is now!