Temperature gauge won't go past the first mark when at normal operating temperature. Replaced with new IVR, temperature sending unit, thermostat and when grounded pegs all the way to the far right. Not sure if there is additional testing or is the gauge shot?
Old post I know, but I thought it was worth responding to, at least for the next guy hitting the search button.
So see if I understand this right;when you take the wire off the sender and ground it to the block, then the needle climbs to the top. Have I got that right?
And while the engine is warming up, the needle moves from somewhere on the bottom, up to about the first mark. Have I got that right?
If yes,and yes, then the answer is simple; the gauge is responding, and the sender is sending.
Now whether or not either of them is doing the right thing, I cannot say.
But I would suspect the sender, so
-Firstly I would check that the body of the sender is grounding to the engine with near Zero resistance. Some guys put sealers on the threads which don't always pass juice. No sealer is needed on brass senders.
-The next thing I would do is check for a signal coming down the wire. Previously 5 volts was mentioned. While this is sorta correct, you need to put an analog voltmeter on that wire. When you do this you will see a pulsed voltage. The stock dash VR is like a signal flasher, in that it sends battery voltage down that wire for a split second and then turns off. A split second or so later it repeats;just like a signal flasher. The result of this is that the sender interprets this as about 5 to perhaps 6 volts.That's why you sometimes see Dodge temp and fuel gauges doing a little tic-toc dance.
-Ok so we have a signal, cuz the meter climbs to the top.And you cleaned the sender off, or it is grounding right?
-Well the next thing to check is to be sure the sender is actually in the water. Some guys stack up 2 or 3 adapters to fit one in, and it takes 3 months to bleed the air out. These senders do not measure air temp; they have to be in the water.So the water temp has to rise, at the sender, from ambient, to near to the stat rating.
-Ok so finally; the water temp has to change the resistance of the sender from very high to very low, as it heats up.You can measure this resistance change with your ohmmeter. The range of change has to be compatible with your gauge requirements.Certain senders won't work the gauge.