Posting about a 99 Ram 1500 4x4 with the 5.9.

I bought this truck in July and the temperature gauge has never worked. I managed to replace the coolant temperature sensor today after trying to fit my fat hands in there and spilling a ton of coolant.

The new sensor didn’t fix my issue. Gauge still isn’t showing anything. It moves to the lowest position when I turn the truck on but will not move any further than that. Anything else I should check before I buy an aftermarket gauge and mount it on my dash?

 

Do a gauge test. Hold in the trip button (on the gauge cluster) while turning the key to run (don't start the truck) and watch to see if the gauge moves. If it does it's a wiring issue, if it doesn't you need a new gauge cluster

 

The gauge moved when i did the test. Can you recommend something else? I’ve never seen the instrument cluster test so at least I learned something new.

 

That tells me you have a wiring issue.

 

Where should I start with that?

 

Say what? By this logic every truck has something wrong with the gauges. And every time the key is turned to run, the gauges are powered anyway so why the trip button?

 

Try it out with the trip button. It will “trip” you out 😂

 

It's been a while since I sold my 2001 with the 5.9. Don't they have two sending units for the temperature?

 

I believe late model 97s, 98s and 99s have only one sending unit? I’m 99% sure at least 99s only have one.

 

98 only has one. The temp gauge gets its clue from the PCM via the communications bus. If all the other gauges are working, then the com bus is working. I would be tempted to plug in with a scanner, and see what temp the PCM thinks the engine is.....