aftermarket gauge hook up -73 Vega GT -part one

[ol55]

The many aftermarket gauges were all disconnected and I am trying to hook them up. Connected the ammeter, oil pressure, and vacuum gauges. Now to the VDO fuel Gauge. I have three slide on connectors and three terminals. One terminal on "full" side, one on "empty side" and one below. The connectors are spliced in. Any hints or suggestions on how to connect?






Thanks,
Larry

[spencerforhire]

Usually the terminals are marked in some way to show where to hook up the wires. Isn't there any letters(B/G/S/L) or symbols(+ or -)?
B- battery(actually ignition)
G- ground
S- sender
L- light
Or if only two are marked + and -, the third unmarked would be sender.
Some gauges use the brass studs as ground; by the look of your pics, yours are like this because you have wires with ring terminals as well as the spades. The lower centered terminal is probably sender, leaving the other two as ignition and light. No guarantees, but you're probably ok to test wire it to see if this is correct. If it's hooked up correctly, grounding the sender wire will make the gauge move.

EDIT: I just realized I have one of those VDO fuel gauges somewhere in the shop; I'll have a look for it and test it to determine the terminal layout.

[ol55]

Thanks for checking! The ring connectors are for another gauge (part 2).


Larry

[ol55]

The VDO gauge is marked. This is how I think the connector is wired:

Pink goes Positive (+)
Black goes to Ground
Tan goes to the Sender

Is that correct?

Pic shows Fuel Gauge as top connector.I can see some of his markings(Green=GM tan, Black=GM Black,and red=GM pink)


Edit: I tried the above wiring and the sending unit went all the way past full. Should be about 1/2 tank. Could be sending unit or ground?

Thanks,
Larry

[spencerforhire]

Some aftermarket gauges require specific senders; they don't necessarily work correctly with every OEM one. If you look up your gauge on the VDO website, it should list what resistance sender it requires. Most older GM vehicles will have "0 to 90 ohm" senders in the tank. A lot of aftermarket gauges have different ranges and some even are meant for senders that work backwards.(240-33 ohm, which I think is "Ford" style).

[ol55]

Grounded out the gauge and the needle went to "E". I think the problem is in the sending unit.

Thanks for the help!

Larry