I've got my hands on a OEM Volvo Vacuum (fuel economy) Gauge made by VDO. It has the following connections on the backside of the gauge:
1) Two electrical connections for the illumination.2) A nipple of sorts which is to be connected to a tube, a vacuum tube I guess (There is a snippet of tubing on the nipple and when I suck on the tube the needle on the gauge moves).
I have a question about the second connection mentioned above. Would anyone happen to know where the tube is to be connected. Is there a predetermined place on the manifold/engine, or is a t-fitting needed to tap into an exsisting vacuum line? Any help would be most appreciated.
Actually while I'm here I might as well ask about the effectivness of this gauge. Do they actually work? Are they reliable?