audiovox aps997 tachless

Hi I install the aps 997,into my old work van it is 1993 ford e 350 diesel ,this van has no tach,I have read the manual and the manual tells me that all applications require that the tach be program,I bought this alarm because it said it would work on all gas and diesel vehicles,I know that in the programming banks it has a voltage sensing option,what wire do I use for the voltage sensing input if it can be done at all.

Any help will be appreciated

Thanks 

Try it with the voltage sense and see what it does. As far as the voltage sensing is concerned you don't need to hook up any extra wire it should sense the difference in voltage through the power wires.

I have done a few of these units but they've all been on gas vehicles.