instrument senders

[Warpspeed]

Tom,
You can slightly tweak where "normal" temperature ends up being on the dash gauge by adding an external resistor to what you already now have.

If you want to shift the needle down a bit towards the cold end, add a low value resistor in series with the sender. Just a very few ohms should do it. A higher value resistor will move it down further.

If you want to move the needle up a bit more towards the hot end, place a resistor between the sender to ground. Several hundred ohms should have the desired effect. A lower value resistor will move it up further, a higher value resistor will have less effect.

You can do the same with the oil sender.

[tom36]

Tom,

If you want to move the needle up a bit more towards the hot end, place a resistor between the sender to ground. Several hundred ohms should have the desired effect. A lower value resistor will move it up further, a higher value resistor will have less effect.

You can do the same with the oil sender.

Hmmm, interesting-  but when the sender only has one wire going to the gauge, and ground is by screwing the sender into the engine, how do you put a resistor in there?  Tom...

[wayne petty]

remember the 10K OHM trimmer pot at the top of this thread from radio shack.. they also have a 1K ohm version and you could use some european style terminal blocks on the first and second wire .. hook it into the harness in SERIES behind the gauge..  in the wire from the sending unit..  this would give you some adjustability to move the gauge..  

you can use the first and second. or second and third lead.. not the first and third lead..

just be sure to either cut off or insulate the unused terminal..

this will allow you to increase the resistance above the senders resistance to center the gauge..

i don't have my thinking cap on..  so i don't know if you need increased resistance or not to center the gauge..

this won't help if you need less..  although.. you might be able to install it on the other side of the gauge wiring.. in the voltage supply wire to reduce the voltage... to work it the other way.. i am JUST not sure that will work...

my brother was the electronics guru.. and he has left the building.. RIP.

[Warpspeed]

Hmmm, interesting-  but when the sender only has one wire going to the gauge, and ground is by screwing the sender into the engine, how do you put a resistor in there?  Tom...

You break the single wire, and insert the low value resistor if it is to make the gauge needle read a bit lower.
This reduces the current flowing through the gauge and makes it read slightly lower.

Or you connect a high value resistor between the single unbroken wire and chassis (at either end) to make the gauge needle read a bit higher.
This pulls a bit of extra current through the gauge, and makes it read slightly higher.

This is only a fine tuning adjustment after everything is working properly, and you just want to shift the "normal" reading position of the pointer needle up or down a small amount.
It is not suggested as a complete fix to match any old incompatible sender and dash unit.