Both temp gauge AND idiot light are stuck

Minuteman96

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93 F250 7.3 4x4.

Temp gauge on dash is inop. Engine temp idiot light is on permanently, from the point I turn it on. It’s been like this since I bought it 6 months ago, and after smelling a slight tinge of burning oil this morning on my way to work, i figured it’s time to stop putting off figuring these two out so I know my engine isn’t overheating or anything like that.

I know there’s two temp sensors on the engine, can anybody tell what sensor is what, what it connects too, and where on the engine it is? Pictures would be much appreciated if possible. Thank you.
 

John Preston

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I have a 87 f250 6.9 and I have a oil pressure gage from a farmall M sticking out the back of hood and a mech temp gage from fleet farm. For fuel I just guess and carry a couple full containers.
 

Steven Sochalski

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Sensor in the first pic is the idiot light. I have an aftermarket gauge digital installed there. 2nd pic sensor is the factory temp sensor. It's back on the block behind the thick black hose. You can also see where my head gasket is seeping coolant. 3rd pic shows the factory temp sensor plug hole in the very front of the block on the driver's side. Directly behind it is the rectangular shaped coolant passage that is seeping coolant in the other picture. 4th pic shows the plug hole for the idiot light on the very front of the driver's side head.
 

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Steven Sochalski

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The sensors work by resistance on the same line wire as each other. So interestingly my engine idiot light still comes on when the dummy gauge reads warm and my aftermarket gets above 220. I don't have the idiot light sensor installed at all and removed it's wire when I redid and rerouted my harness. My dummy gauge sensor was bad and I replaced it with a newer Ford sensor, not the expensive one called for. The resistance must be slightly different, so my dummy gauge reads way to the left. If it's over 1/4 I'm getting hot and the resistance value must be close to the same as a closed over temp switch.
 

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CDX825

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The over temp sensor is on the front of the drivers side head. If you unplug that your regular temp gauge should go back to acting normal.
 

TNBrett

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The over temp sensor is on the front of the drivers side head. If you unplug that your regular temp gauge should go back to acting normal.
If it does, that over temp switch is bad. If it doesn’t then you probably have a short to ground on that circuit somewhere.
 

Minuteman96

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Okay so returning to this, looking like I just need to replace my sensors. Does anyone have part numbers?
 
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