temp gauge/sender question

[x-unimog404]

Having trouble getting my temp gauge to work proper on my 73 fj-40.
Gauge is an H at startup and will not go to C, or goes down slowly.
I removed the connector fron the sender and put it to ground, and the gauge goes to C with the key in the on position.
I tried this on two senders I have from the same year engine. The sender towards the rear of the head with the spade connector.
Do I have a bad sender (s), or am i Missing a ground somewhere.
Motor was not running prior to tearing everything apart, so I have no reference to know if it was working before.
Thanks. Rob.

 

[s79bj40]

sounds like the connections on the back of the guage are mixed around, normally grounding the temp connection at the sensor should make the guage jump to hot. The sensors reduce in resistance the hotter they are, hence yours slowly moving to the C position, ie its just reverse operation. Something is stuffed with the guage connections, not the sender.

Sam

 

[Yoda]

On my 71, the gauge is at "hot" when the engine is off or the sender is unplugged. Turn the key on, and it goes to cold. Ground the sender wire and it goes to cold.

Are the sender in the engine, and the guage package from the same year?

 

[x-unimog404]

Actually, that particular gauge is out of a 71. The sender is, i would think, out of the original engine. I still have the original, quess I can put that one in and see what happens.
The way it is now, when I disconnect the sender, and attach the wire to ground, the gauge is a H. turn the key to on, and the needle jumps to C. re-connect the wire to sender, and it goes back to H.

 

[s79bj40]

how stupid do i feel. maybe i should just shut up and go back into hiding

 

[Yoda]

Yeah, I don't know what year they changed (it was early 70's). I had to buy my 71 sender from the dealer, cause the aftermarket one I got was the wrong way.

I am in the process of changing my dash panel to a 78 one, so I will need to change my engine sender to the newer type. Do you want to trade senders, or are you going to change the gauges?

 

[x-unimog404]

going to change the gauges in the cluster first, the see what happens. I did notice that the original temp gauge has the pointer below the C even before installing, where as the other is on H.
Well see what happens.

 

[x-unimog404]

ok, im stumped now.
Put the original temp gauge back in. needle is way below C.
Turn ignition to on, nothing moves.Needle does not come up at all.
remove wire off sender and ground it, and the gauge goes to H.
Oppisite of the other gauge off the 71.
I hate electronics!!
Dont know what else to test.

 

[65swb45]

The guages did change from 72 to 73, and they do work opposite. The fact that your guage is way below the C is an indicator that the guage has suffered a short. It now has the ability to jugde that there is a current, but cannot accurately reflect it in increments any more. This is why it can still jump to H.

You need a new guage and FWIW, you should know that 73 used a one-year-only guage.

Hth

Mark

 

[x-unimog404]

Thanks for the tip. I quess Ill go over to the classified section and look for a 73 temp gauge.
Thanks.