My wife is a little upset with me right now because I have been throwing money at this problem instead of trying to properly diagnose it in the first place so here is hoping someone can help out.

1985 E-150 Van. 44,000 actual miles. Water temp gauge reads unusually high and seems to flucuate. All coolant related items have been replaced, including the sending unit, with a proper flush and fill as well. Infrared readings are excellent so I know it is not overheating. Voltage to the cluster is a steady 12 and resistance across the gauge is 12.8 ohms. I have been hesitant to replace the gauge because I do not believe it to be the problem and here is why. Though I have yet to replace the oil sending unit and so these may not be related, the oil pressure gauge fluctuates from a little over 1/2 to almost redline. I have assumed these two are related since they are both fed off of the same 12v circuit. Other misc notes: 1. The wire feed to the water sending unit is good and not shorted. 2. The 12V feed to these two gauges ohms out to ground at about 35. I see that there is a resistor in circuit, though I do not know its purpose or rating.

 

If you've checked it out and it's not running hot then don't worry about it.