Temp Gauge and headlights (strange)

[simpleman83]

So, I have been having problems with my water temp gauge (i think) because it fluctuates back and forth based on a lot of different things. The most recent thing being that I noticed when I turned the truck off, and the lights were still on, the temp gauge started to climb..... What does this mean? Would this have something to do with the sending unit? The temp gauge tends to climb if I'm sitting still sometimes and other times not, turning on the heat helps sometimes, others not, when I'm running on the highway the temp is usually way low, other times just where it needs to be. After I shut off the engine from being at running, the gauge climbs then once the key is off, the gauge will go back down. Not sure if this last one is normal or not??? Anybody got any clues? The one that I think is extremely strange is the lights having any affect on the temp gauge....thats just weird! Ohh and by the way, I installed a new thermostat, water pump, fain clutch, radiator, so its almost 100% the gauge in my estimation.

 

[noJeepshere]

my guess is that its wearing out and going to point at 260 deg for ever. find a boneyard and get one from another truck. if it does the same thing, its prolly your sender. if not that, i dunno

 

[simpleman83]

anyone else got any ideas? I'd really like to know why the lights would affect the temp gauge...

 

[mrdrinksalil]

I dont think you have anything to worry about as long as the temp isn't getting too hot. Once you shut the engine down your water pump isn't circulating water so its not uncommon to see the temp rise once the engine is shut down. As for the gauge going down after you turn the key to the off position, it needs ign. power to work in the first place. And for the part about the temp going down after you turn on the heat; the coolant is now circulating through the heater core and has another "heat exchanger" in the system.

As for the lights having anything to do with it... i havn't a clue

 

[Goose]

If you have that much variance, especially with another electrical item (lights) I would look at your gage first. Take apart the dash and clean all the connections, put her back together and see what happens. Also check the grounding block behind the dash. It is up kinda behind your headlight switch. I had crazy things with my electrical on a previous truck that finally turned out to be grounding problem at that location.

 

[simpleman83]

That definatley seems like it could be more of an issue on this one. I'll have to look into the grounds surrounding that area. Thanks

 

[mrdrinksalil]

it ONLY does it when the lights are on, or is it dark out and thats the only time you notice it?!

 

[simpleman83]

it ONLY does it when the lights are on, or is it dark out and thats the only time you notice it?!

Only when the truck is off, the ignition key is turned and the lights are on. I just noticed it. It goes all the way from running temp to extreme hot fairly raipidly.

 

[wheels87k5]

I had the same problem, temp gauge going full peg and the temp was actually about 210 degrees.
It could be a bad gauge, or, it sounds like a grounding issue.
I installed an aftermarket temp gauge in mine, and noticed, while driving, it would still peg. And when I would kick the air duct under the steering colomn, the needle would go to the actual temp.
This problem is causing my oil pressure reading, the battery reading and the temp gauge reading to be a little higher than normal.
In this case, it's a grounding issue that I'll fix when it gets warmer.
It's nothing hard, just a little time consuming. Good Luck.

 

[simpleman83]

yeah, and I hate wiring so that'll make it fun