Tach connection

[Paintjar]

I am working on a 1991 Rockwood Driftwood. I am into the dash and found a VDO 7000 Tach. The back has 3 blades, 1 is +, 1 is -, and the one in the middle is my question. I found no loose wires for this. Where does it come from? The dist or module somewhere? I don't know where to look for a trace. The motor is a FORD 454 fuel injection. Can any one direct me as to where I may find an extra wire hooked up? I am sure in it's day the tach was working. Thanks for any help.

[LVJ58]

If it has a coil and distributor look for an extra wire on one of the 2 terminals on the coil. If the coil is incorporated into the distributor, check for an extra wire there. I would also trace the + & - wires and see where they connect. The tach may only require the 2 wires and the third blade not used. Hopefully you'll get a response from someone on the forum who knows for sure.

Good luck and let us know how you make out

[Paintjar]

Thanks for the help. I am new to Fords, but I found the coil. It had a red wire, hot, and two others. I lost them in the trace and could not find them coming out at the firewall. I jumped awire to them and touched the center blade of the tach and it worked. If I ever discover those others wire colors I will know what they are. All is well and I have the tach. Thanks again for your intrest in helping me.

[LVJ58]

Hi Paintjar, glad you found the problem and now have a working tach. I wasn't sure about that 3rd blade, but apparently it serves a purpose. Do take care and travel safe.