I have a electrical autometer trans temp gauge. It was working in my friends car after we removed it. I just went on a 35 mile drive and my gauge nevered moved, but it has power since it does move a tad when you first have the key/engine is on. During that drive i stopped at a gas station and i swapped the sender wire with the power and it pegged beyond 250. what can cause the gauge not to work properly? im not a wiring wiz, but i can do the basic's. Would a short or a bad ground cause it? I have it wired like this. the gauge has 3 prongs and a light. One prong marked 'S' has the sending unit goig to it. One prong marked 'I' has the power source going to it from a fuse tap, and the third prong called GRD is grounded to the shared spot i have the ground for the gauge light. Power of the lite is tapped into the wire that powers the gauge. what am i doing wrong? i should start checking my grounds i assume?
Steve03
still scratching my head on this one. Just to came back in from te garage and heres a senerio. Pwr wire hooked up, ground hooked up, turn key, pegs beyond 250, hook up sending unit wire and it dips slightly to 210-215. what is my issue? sending unit wire is the culprit??
Call autometer and ask them for the specs on the sender and then check the sender... and btw thats an electrical gauge not mechanical
First, you need to adjust your post in saying that you have an electric gauge and not a mechanical. Mechanical gauges only have power for back lighting.
Your sender will get it's ground from the transmission. With heat the sender then gives a feedback of ground to the gauge. With that being said, you could have a few problems. Either your engine/transmission does not have a good ground (unlikely if you are running EFI) Or you have bad connection of ground from your transmission pan to the sender. Common causes of this would be from using teflon tape.
To check and see if the gauge works, touch your sender wire to a known good ground and it should bury the gauge. If it does, the gauge is fine.
The sender is a little tricky. You will need to see if you have continuity between the sender case (where the hex is) to ground. This checks to make sure you have good ground to the sender.
Also see this......
http://www.autometer.com/productPDF/1079A.pdf
Your sender will get it's ground from the transmission. With heat the sender then gives a feedback of ground to the gauge. With that being said, you could have a few problems. Either your engine/transmission does not have a good ground (unlikely if you are running EFI) Or you have bad connection of ground from your transmission pan to the sender. Common causes of this would be from using teflon tape.
To check and see if the gauge works, touch your sender wire to a known good ground and it should bury the gauge. If it does, the gauge is fine.
The sender is a little tricky. You will need to see if you have continuity between the sender case (where the hex is) to ground. This checks to make sure you have good ground to the sender.
Also see this......
http://www.autometer.com/productPDF/1079A.pdf
Did a little work tonight and changed the ground to a better spot and a thinner guage (thinner than pwr/sender). Resistance was flucuating between 0.3-0.6 for the sender. With the wire off the sender, its like at 1.7-2.0. where do i need to be? with the new ground installed, when i unplug the sender wire from gauge, (pwr and ground are connected to gauge), it will go to zero where it should, but with it connected, it goes back to beyond 250 degrees. so it sounds i may have a short in the sending wire? tonight i will try a brand new wire and see if that will work.
During that drive i stopped at a gas station and i swapped the sender wire with the power and it pegged beyond 250.
This might prove to be fatal for the gauge (not sure). But what you did was you put power to the gauge where it normally reads a ground from the sender.
Let's put that aside for a moment. The is no reason to fiddle with the power and ground to the gauge, you have established you have power and ground to the gauge. What you need to find out is the sender. You started out by saying the sender will not read hardly at all, but are now saying it pegs the gauge when you hook up your sender wire?
If it pegs the gauge......your sendor is either bad (full ground) or the sender wire is rubbed somewhere to a full ground.
If the gauge isn't reading the way it should, you are either not getting a good ground through the threads of the sending unit, or the sending unit is bad.
This might prove to be fatal for the gauge (not sure). But what you did was you put power to the gauge where it normally reads a ground from the sender.
Let's put that aside for a moment. The is no reason to fiddle with the power and ground to the gauge, you have established you have power and ground to the gauge. What you need to find out is the sender. You started out by saying the sender will not read hardly at all, but are now saying it pegs the gauge when you hook up your sender wire?
If it pegs the gauge......your sendor is either bad (full ground) or the sender wire is rubbed somewhere to a full ground.
If the gauge isn't reading the way it should, you are either not getting a good ground through the threads of the sending unit, or the sending unit is bad.
Finally got it fixed! It was the sending wire not grounding itself to the stud on the unit, but to the nut that the stud protudes out of! That little O-ring part where i had the wire crushed in it, was just touching that nut to give it a bad ground. I flip the O-ring around and all is good now. stupid thing was driving me nuts and it was a simple thing the whole time
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