New here. I am running a EMU Black in a 78 VW Rabbit. I decided to use the original gauge cluster instead of the display unit. The Rabbit came with a tachometer and I have the white wire from the ECU to tap into the tachometer. I was told i will need a type of signal multiplier . Not sure what that is. Any ideas? Thanks. Tony
You can use something like those to generate a traditional square type wave for your existing tachometer to work.
I don’t know what tachometer the Rabbit used, but I can drive the stock VDO tachometer in my 911 directly from the ECU. The same basic tach was used in the 60s, 70s and 80s in various German vehicles. Normal operation is for the ignition system to ground the signal wire (mine is marked TD on the back of the tach). Connecting the tach to one of the ECU digital outputs provides the same functionality. Here’s my configuration:
The multiplier is a 3 because my 6 cylinder engine generates three ignition pulses per revolution.
Hope this helps,
Steve
Yes it helps. I had a friend help install the ECU and he is not sure how to incorporator the tachometer. It is a VDO and is similar to most German cars from that era. I will give it a try and post some results in the future. Thanks again for the input .
This is the back of a tachometer like mine. The output from the EMU Black should go to the terminal marked “TD”.
Hi Steve. So you are saying that I can take the signal from the ECU Black after making adjustments to the ECU outputs for the tach, I’m using. I then do not need to buy a Autometer adapter? And where are you located? Thanks. Tony
so does your tachometer work or not at all? what year 911?
I have the Tachometer from a 78 VW Rabbit. It works. It looks like i will have to purchase a RPM adapter to make it work. Thanks. Tony
Sorry I meant to as Steve what year 911 he had and if his rabbit tach is working or not. As you have said, most of these things need tach adaptor. The 911 maybe newer and they can use a different computer system to drive it.
No problem I will post a update when I install the RPM Adapter. Tony
Why not just try a pullup resistor. 1k to 12v. You will be converting the 0v signal to 12v signal.
That sounds simple but not sure how to. Would need a sketch showing how to connect.
It should have this internally already, enabled when aux 4 is used as the tach output.
I’ve found with older tachometers that are designed to pickup off the coil negative, Black and Classic need an adapter. I haven’t measured it personally but supposedly the negative of the coil field collapsing can push voltages well beyond 12 or 14v (I’ve read 60, not sure about that tho), some tach’s (Toyota’s for example) there’s an inline resistor you can bypass and then Aux 4 does the job.
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Then he could pull to ground. Just try to get the signal in the right condition.