Autometer Fuel Gauge

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Jan 5, 2003
San Antonio TX
OK, got the sending unit in and wiring up the autometer gauge to it. It's a mechanical gauge and it has three posts. One 12v - one Gnd - one to the sender. Is the wire for the sending unit the Yellow w/ Red Stripe? That is what I have and I have everything connected per manual yet the gauge still pegs full. What could it be? I've disconnected the ground and nothing changes. Is there a way to test the gauge itself?
It is not a mechanical gauge; it is electrical.

Yes, the red/yellow factory wire should be the wire you connect to the center of the fuel sender and to the sender connection on the back of the gauge.

The ground on the back of the gauge, where is that connected to?

The ground wire on the tank, where does that terminate to?
I used the factory RY wire from the harness and just extended it to the gauge itself. The ground on the back of the gauge is hooked to one of the mounting bolts for the brake MC. Not sure where the factory one on the tank goes. I had no problems with wiring on this rig prior to changing the gauges out. Everything was operational.

Just double checked the grounds and they appear OK. I used a jumper from the lug on the tank to a seat mount and the same for the ground on the gauge.
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May check the required ohms of the guage. If it's different than the ohms requirement of the sending unit, you'll pull your hair out trying to figure it out. The instructions for the gauge should tell you the olm requirement of the gauge, they need to match. You may need to go to a different (usually after market/universal)sending unit for the gauge. Hope I made sense???
Do you have continuity from the sender end of your red/yellow wire to the gauge end?

How did you verify this?

Have you verified that your ground for your instrument, the one you ran to a mounting bolt for the brake master cylinder, is in fact, a good ground?

How did you verify this?
pretty sure Toyota sender is somewhere around 17ohms empty and 120 ohms full, while most (not all) of the autometer fuel gauges are 0-90.

this might not be your specific problem but if your Autometer gauge is the 0-90(or doesn't match the Toyota sender), your going to need a resistor inline or matching sender and gauge
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haven't checked the continuity of the YR from the sender to the gauge, will do shortly, the grounds were verified using a jumper cable to another ground cable. should be good. not that it matters but the stock gauge worked fine prior to this mod. I read on another board that someone was having a similar problem and they switched the 12v side with the sender side and their gauge worked.

On the sending unit, it's a new autometer unit so it should be good....

PS Continuity of the YR is GOOD.
On the sending unit, it's a new autometer unit so it should be good....

That is fine, but have you verified that the sender is compatible with the instrument.

Auto meter does make a few different sender/fuel gauge combinations.

Not 100% positive they are compatible even tho they are both AM. I got the sending unit model # from a post on this site that someone else has installed. I will call AM monday to verify compatibility

Is there a way to check the gauge?
OK, I found this on the sending unit: Sending Unit, Fuel Level, 240-33 Ohm

It would appear that this unit is for electronic type gauges and the ohm range is way off.
am I on the right track?
It would appear that this unit is for electronic type gauges...

Which again, is what you have; an electronic instrument.

What are the sending unit ohm requirements for your instrument? This information is on the Auto meter web site, along with the information sent along with your instrument.
Since I got my gauges used there is no serial or model # on them however, after looking on autometers site and comparing as closely as possible it appears the ohmage required is 0 - 90 .
Just a WAG but, is it possible to wire in a few resistors inline to reduce the ohmage?
Just a WAG but, is it possible to wire in a few resistors inline to reduce the ohmage?

It may be, but I would obtain the correct sender and gauge combo. All my Autometer gauges have a four digit number on a sticker that identify the gauge. Go to their Web site and find the proper sender that matches your gauge or purchase a new gauge to match the sender since it is already installed; that seems the easiest.
The label on the gauge is unreadable/faded so I guess I'm SOL on that issue but, if it is one of the older Phantom gauges, which I'm about 85% positive it is, Then why wouldn't the stock sending unit work?

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