Dodge 99 ram 5.9 has only one hole in the intake for the coolant sensors, one for the computer I have plugged in,
The one for the temperature gauge is not as there is no hole in the intake,
How does the 1999 run the computer temperature sensor and the temperature gauge with only one hole in the intake?
how do I get my temperature gauge to work?

 

There is only one sensor on the 98 and up trucks. The instrument cluster gets all it clues on what to display from the PCM on the communications bus. If you have only one gauge that isn't working properly, it's likely the gauge itself.... Best bet would be to plug in with a scanner that can read live data, and see what the PCM thinks is going on. It's possible the sensor is just bad, so the PCM thinks the engine is cold all the time, or, it may just be the gauge has failed.

You can do a cluster test as well. Press and hold the trip/reset button, and turn the ignition to on. (don't start the engine) The cluster test will start, and you can let go of the button. All the lights will come on, all the gauges will go thru a full sweep. The odometer will likely display a few codes, but, you can ignore them. Just watch and see if your temp gauge does its full sweep.

 

This is a 1999 5.9 that I just put in my 1996 Dodge Ram 3500, yes there is on one hole in the intake, there is no hole for the temperature sensor so my temperature gauge does not work, how can I make this work? Thermostat housing with a temp sensor in that? Drill and tap a hole in the intake right by the thermostat housing?

 

Either would work, or, if you still have the 96 intake manifold, swap that in. Drilling and tapping might be the easiest.

 

If you look on the 99 intake your will see a flat spot where the other temp sensor would go. Another member here drilled and tapped it for the sensor for the gauge.

 

Keep in mind, I do believe those are NPT pipe threads.