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 |
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