Hi all.

Searched, stared at Jetta cluster PCB, asked elsewhere so hope posting
here is ok. Got the part for free, so might as well see if I can't use
it.

David Marshall posted a while back (archives) of swapping in a Mk2
tach. From his post:

" - The hardest part of the whole swap was determining what leads were what
in the tachometer.  On the 85 thru 89 tachometers there is a plug where pin
one is ground, pin two is blank, pin three is 12V and pin four is the
signal from pin #1 on the coil.  I removed the connector from the Jetta PCB
and soldered some 22 gauge wires to the connector and attached them to the
proper location.  Double check that I am correct with an Ohm meter first! "

The Mk3 uses a (pulse?) from ECU. I presume above "12V" means ~ 10V
from the voltage stabilizer. My tach has 4 connections (pins) but no
numbers present on tach or PCB. Tach "plugs into" PCB.

Backside of my tach image: http://tinyurl.com/445kluu  Anyone know
which # pins signal, power and ground connect to? My guess is that the
middle pin is blank as per Davids post and 4 is the upper pin as
labelled by me.

The tach is a sealed unit so now way to tell by look at coil etc.

A while back I connected the tach to 1 from coil. It was jumpy as
heck. (another clue that it's designed to use ECU signal). I labelled
a pin but  am not certain of connections. Would hate to get it wrong
and screw up the ECU.

FWIW, under OBD1 Motronic, 68/22 on ECU connects to 10/28 of plug to
Mk3 cluster. This # 10 connector is referred to as "1" or "W" in A3
Bentley so I'm certain that's the signal wire.

Thanks for any help!

Neil.

--
Neil Nicholson '81 VanaJetta 2.0 "Jaco"

http://tubaneil.googlepages.com/

http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines