# Tach Problem



## BSD (Jul 8, 2008)

Alright, I know this doesn't necessarily fall into the "CIS" category, but you guys have always been helpful and I never got a response anywhere else.








Okay, so.
To start off, my car is a CE1 car. I picked up a cluster from a 98 Jetta. ( Which is CE2 ) Its the silver backed gauge with the orange needles.
I spliced the wiring and got everything to work except my Tach and turn signals. ( Not that worried about signal display )
I understand that B19 ( Red/black ) is the tach wire in CE1.. But when I wire it into T28/10 ( White connector plug on back of cluster) the tach needle will sit at 3k, then jump to like 5k.. then back down to 3k.. etc.
Is there something I am missing here? I'm tired of not having a tach...
Thanks in advance.
Steve-


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## BSD (Jul 8, 2008)

Bumpity bump bump?
Steve-


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## wclark (Mar 28, 2001)

*Re: (BSD)*

I havent actually LOOKed at the tach signal on my B4 Audi but I it runs from the ECM to the tach input on the instrument cluster which I think is similar to your Jetta cluster. As it is from the ECM and to what may be a digital cluster control, it may not be as simple as a varying frequency string of pulses. It may be a data stream.


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## BSD (Jul 8, 2008)

That would make sense since it is a digital cluster, opposed to my analog one stock. But!The only thing I don't understand, is from what I can see in the diagrams at A2resource, the tach signal input on Mk3's come from negative side ignition coil, fusebox, cluster.
Maybe I am just reading it wrong..








Steve-


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## wclark (Mar 28, 2001)

*Re: (BSD)*

The diagram I found online at http://www.vaglinks.com/Docs/V...m.pdf shows a VR6 setup with the Coil connected only to the ECM and plugs...(page 57 of the pdf) It is not clear on this set where the instrument cluster lines come from (on page 6 and 9). The page from where the tach signal is sourced (comes in T28/10 on page 6) is not present.


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## BSD (Jul 8, 2008)

*Re: (wclark)*

Looks like you are correct clark.








Alright, so I found this on A2resource.
http://a2resource.com/electric....html
Pin 11 on the controller is a tach signal. As far as I can see, my ecu and other models, besides motronic, are not digital. SO, maybe only motronic models or later ecms can use later style clusters?
Thanks again clark, you rule. http://****************.com/smile/emthup.gif 
Steve-



_Modified by BSD at 12:01 PM 8-13-2009_


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