Need help installing dakota digital W-terminal adapter.

[anarchyx34]

Has anyone installed one of these before? My car is a swap, so it has the gas cluster and wiring. I have the correct alternator, I just cant figure out which wire on the cluster's harness goes to the tach. The bentley manual has the most useless wiring diagrams and shows 3 wires going to the tach. A red wire, red/white (which I verified is 12v) and a green. I tried spinning the alternator by hand to see if I can even get the needle to jump, but nothing happens and the green light on the adapter dosent blink. Something I'm doing wrong?

[regcheeseman]

Yeah, you're doing so,mething wrong.

The alt needs a live feed to energize it's windings and produce power (and W term output) when spun.

you can do it on the bench with a battery and a drill to spin the alt - you'll never do it by hand.

[anarchyx34]

Well I did check with a voltmeter set to A/C and I am getting voltage when I spin the thing. But the fastest I can spin it is to 1 volt, which maybe isnt enough. I am of course doing this with the ignition on. My main problem is which wire runs the tach.

[RabbitJockey]

here are the 2 different alternators i have, there is also another kind, like what's on my dads 85 jetta td, i'd take a pic but he's not home,  but it's not hard to figure out which it is, as it has a raised W marking next to the terminal,  there is another plug but it has something to with noise, as you can see with the top alternator (the one actually on my car) there is a noise filter thingy, and on the second one there isn't, i think the noise plug is marked b or d or something

[anarchyx34]

Mine's the later style, but it's definitely a W terminal alternator.

[anarchyx34]

Thing still dosent work. I have the engine running now, and the light on the converter flashes, meaning it's getting a signal, but nothing on the tach.

[anarchyx34]

I think my cluster's bad. I've also had ever since the swap, a low coolant light that flashes constantly, even when the sensor is jumpered. I've double and triple checked all the wiring and still nothing.

[anarchyx34]

Tried swapping clusters, and it still dosent work. I verified with an oscilliscope that the dakota digital thing is putting out a signal. I'm thinking maybe a tach amplifier is needed?

[anarchyx34]

Just got off the phone with dakota digital, turns out the gas tach requires a high voltage spike (25v or so) that the dakota digital module cannot reproduce. So it just simply wont work. Now I need to find a CE2 diesel cluster with tach.  :evil:

[RabbitJockey]

just convert a gas tach, it's easy and it costs like 2 dollars

[anarchyx34]

Not sure if it can be done on a '92 tach since it's a combined electronic module (includes the warning lights and everything). The tach isnt separate on these clusters.

[bigJ]

Just this past weekend I installed a Dakota Digital converter on my 81 Rabbit diesel. I ran a separate wire from the back of the tach to the converter. At first I couldn't get the tach to read the correct rpm's. I found out that that there is a trace on the cluster (# 5) that connects to a wire that eventually goes to ground somewhere. With a piece of electrical tape I covered the contact on the interment cluster and it worked. I know this is for an A1 but maybe it will help.