Mk1 tach install (Dakota Digital)

[veeman]

A few weeks back I ordered a tach converter from Dakota Digital (the DSL-1) and I finally got the chance to install it last night into my caddy.

I used a tach from my old rabbit GTI and it fit right into the cluster as it should.  The "circuit board" (film) on back of the diesel cluster already had the right circuits on it and all I had to do was swap over the tach and put the washers and brass nuts on where they were supposed to be.

When I replaced my alternator last time, I got one with a W terminal, so all I had to do was run a wire into the cabin for that signal and then find a keyed power and ground.  The tach signal goes up to pin #5 on the instrument's cluster's plug.  It's a red wire with a black stripe and it was already in the harness despite the fact that the car never came with a tach.  Pretty cool.  

Now... since the tach is from a gas car, the redline on it was not exactly appropriate for the TD, so I took some markers and recolored it to make the "orange zone" start around 5k rpm.  Seemed to work out really well.  Right now the TD only revs to about 4300 before power falls off, but hopefully the Giles pump will help that.

Calibration was easy with the buttons on the DD adapter and since I knew from the dyno what my idle was (a little high at 925 or so), it was easy to set.

Here's how it turned out:



In the pic you can still see the center hole / post from where the old clock was.  No way to get rid of that, but it's not really noticeable when you drive.  

So far, the tach is working great.  It's interesting to see what the actual rpm's are when I shift and on the highway.  With the FF five speed, I'm shifting at around 3000 puttering around town, just short of the torque peak at 3400 on this engine.  Interesting.   The DD adapter works as advertised and it's nice to have a tach...

[BioDieselVW]

Hi I have a DD DSL-1 and im about to instal it. Your post is a great help but if you could explain in more detail how to wire the  DD DSL1 i would appreciate it. I just confused on how it gets wired and where the pin #5 goes? Also the sig ground and sig in and the w terminal off the alternator. Thanks Paul

[veeman]

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you could explain in more detail how to wire the DD DSL1 i would appreciate it. I just confused on how it gets wired and where the pin #5 goes?

Pin 5 is the fifth pin on the instrument cluster plug.  If you pull out your cluster from the dash and unclip the plug, You'll see it.  It's a red wire with a black stripe.  I cut that wire about 6" back and then attached the wire that goes to the 4-cyl output of the DSL1 (output 3, I believe)

>Also the sig ground and sig in and the w terminal off the alternator. Thanks Paul

In our application the sig ground isn't used.   SIG IN is the signal wire coming from the ALT W terminal.  You'll have to run that wire from the alternator into the cabin and to the DSL1.  I used an existing grommet that I had used for the oil pressure gauge I installed.

Basically, there's four wires...

Power
Ground
SIG IN ( from alt W)
OUTPUT 3 (to instrument cluster pin 5)

Does that help?

[BioDieselVW]

Thanks I got the tach installed and it was very easy. I even used your idea to change the reline w/ an orange sharpie. Thanks

To anyone thinking of using the DD DSL1 its the way to go!!

[RAMMSTEIN]

Peak torque is usually at 2400, you've got some mods to have it at 3400?

So far, the tach is working great. It's interesting to see what the actual rpm's are when I shift and on the highway. With the FF five speed, I'm shifting at around 3000 puttering around town, just short of the torque peak at 3400 on this engine. Interesting. The DD adapter works as advertised and it's nice to have a tach...

[rabbitman]

I just installed a tach on my rabbit and want to know if it's accurate. With an FN tranny in 5th gear it'll do 70mph/3000rpm, 60mph/2500rpm. I revved it to 3400 in neutral and it sounded like it was gonna blow up. I found a website that says 5th is .71 and final drive is 3.89. Does anyone know if my mph/rpm sounds rights? The tach is weird, it has a transducer that clamps on one injector line and senses the pulse or something, says it doesn't matter how many cylinders you got.