[V8] tach jumping
jward at mti-interactive.com
Thu Mar 4 10:32:04 EST 2004
The archives are unfortunately limited these days, so here is a post I
did last June.
Just tackled this one myself. Does the speedometer come back to life by
gently tapping on the top of the instrument cluster? How about when you
beat on it? :-)
Remove the instrument cluster, dissect it, de-oxidize and clean all
metal contact pins / sockets, reassemble. Ask the guys down at the
electronic parts store what their favorite contact enhancer is, and
follow the directions on the product.
Don't put the rest of the dash back together for 1 week; make sure you
got it on the first attempt. The first time I did it, it lasted 4
months. My problem was that I didn't use a contact enhancer to help
out, just scraped the contacts clean with a knife. I tried it a second
time with the enhancer and it still was jumpy. Second try with the
enhancer (third time total) was the ticket. I believe my biggest
culprit was the 5 (or so) pin connection from the back of the
speedometer that plugs into the header on the main circuit board (the
one that takes 4 Phillips screws to undo).
This project takes for ever the first time, I have actually gotten
faster, though. :-) Pay attention to the 2 different lengths of Allen
screws (plus a third length, qty 1) and that the short ones thread into
aluminum, long ones into a retaining clip.
Remove the metal speaker grills from the plastic in-dash housings using
a small flat blade screwdriver between their seam near the side window
defroster vents. There is (1) 5mm Allen screw on each side. (1) Allen
screw in the center of the defrost vent next to the front windshield.
Remove the knee bolster and glove box; anywhere you see an Allen screw
on these babies, remove them. One exception, open the glove box and
there are (2) access holes in the top metal plate, that (barely) allow
access to the Allen screw (one per hole). DON'T remove these all the
way, just loosen them, you will see why when the glove box slides
forward and off the 'pinchers' that you just loosened.
Next, (2) Phillips screws in the bottom of the steering column plastic
shroud; just remove the screws and the top half, you can leave the
bottom half hanging there as you work around it. There are (2) Allen
screws in the end of each wood grain part (so 8 total), and (1) each in
the (2) black metal brackets along the bottom edge of the long wood
grain part. (1) Allen in the hole inside the ceiling of the instrument
Now the Allen screws just a 1/4 inch down from where the crash pad meets
the huge aluminum piece that goes the width of the car (can't remember
how many, I think one to the left of the steering wheel, one at the far
right and 2 or so to the right of the steering wheel.)
Now pull the dash pad forward and slide it out the passenger door. Next
the easy part; remove the (2) Allen screws on the left of the cluster
(top one is that odd ball one I mentioned earlier, that is unless a
previous owner lost mine and substituted with this one that is not a pan
head). It *will* come out now, trust me. You can remove the speaker
pod on the left hand side, but a little patience coercing it to come out
will save you a ton of time removing the speaker pod.
There are several connectors on the back side of the instrument cluster,
use a small flat blade screw driver to pop up the 'keeper' on the back
of each plug, then each connector will come right out. You may have
nylon 'zip' ties holding the wire harness to the back of the cluster via
the plastic loops there; you will need to cut these ties, being careful
not to snip any wire / insulation.
It's free! Set it face down on a clean, folded towel on the kitchen
table, and remove all the gold colored Phillips screws on the back of
the cluster. Take the flat ribbon cable from the dimmer, unplug it, and
carefully remove it from the plastic 'C' holding it in place. I think
there is also one going to the back of the Speedo, too. Now loft off
the 2 white plastic bowls from the back of the cluster. Remove the
remaining gold screws to get the circuit board up from the 'glass'.
Remove the (4) silver screws holding the speedometer to the circuit
Now clean every connector you see, before reassembly (just the reverse
of disassembly. Put it back in the car; be careful to get the 'pins' to
go into the rubber grommets on the right hand side. Put the (2) Allen
screws in the left side to secure and go for a test drive. Try using
cruise control, as this must draw extra current through the sped
connectors (speaking from experience).
You can now set the dash pad back in place, but like I said, give it a
week before you put in a single screw. One more 'gotcha'... When
reinstalling the dash pad, there is a finger / catch above the glove box
area; make sure this lines up before screwing it back down.
Dang, I think it actually took longer to type this than to do the actual
repair... Never mind, Jeff. Just bring it out to Portland, OR this
weekend, I'll take care of it. :-)
From: kyle leatherwood [mailto:kyle_leatherwood at hotmail.com]
Sent: Thursday, March 04, 2004 5:46 AM
To: v8 at audifans.com
Subject: [V8] tach jumping
A friend's V8 has just started to have the tach begin to go out while
driving. It will work fine then jump all around or just quit all
If you whack on the dash to sometimes it will stop and sometimes it will
really make it quit. I see on Blaufergnugen's website the same
but having to do with the 100 and 200 clusters and with the speedometer
the tach. Anyone experienced this and is there a fix or should he bite
bullet and get another cluster?
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