1997 freightliner classic dies

I’m just guessing. I too would try unplugging the sensor. If it’s like the coolant sensor, the yellow light should go on. Then jump the wire/plug with a paper clip. Light should go off. Again I’m guessing. Might cause the red light and shutdown. Either way. My thoughts are if it still does it while unplugged and jumped, it’s the wiring. Since you already replaced the sensor it’s probably the wiring. Then maybe trace it back, look for brittle area near heat. I had this problem with coolant level sensor wiring. Just cut it back a little at a time, connecting a new wire. Once it worked, I spliced it in. If you cut the wires back far enough and twist them together, and it fixes the issue, you’ll know. Whole harness isn’t too expensive, but probably just the one wire broken from heat. I hate to start cutting wires, or even sticking them with a test light. There are fancy tools for detecting shorted wiring. Not practical though. Sometimes the ecm will have a bad terminal connector pin. Usually looks dark colored compared to others. Mine has one, but it doesn’t affect anything. New battery in ecm is besides the point. All it does is keeps stored codes (yellow cel) available for diagnostics. Ddec 3 didn’t have a battery. Didn’t store old codes. In case you don’t know. Turn key on, hold override/check button. Count yellow flashes ( stored codes) they will show in most recent order. Then will repeat. Followed by red (active) codes. Get any current or stored codes. The ecm is probably fine. New engine harness now or eventually is money well spent. Plan on changing mine eventually. Might as well. Already have new injector harness. They’re known for going bad.

 

I doubt it. Never had that issue. Just inoperable speedometer and cruise

 

These pics are for DDEC 3-4. P3/133 on the Engine Sensor Harness connector is the location for the coolant temperature sensor. If somehow the coolant level sensor is the cause (as some previous post supposed), it's location is H3/115 on the Vehicle Interface Harness Connector.

 

Are you checking voltage across the pins, ot to a ground?

 

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Have you done a flash code check yet? I know you said interpreted an overheated sensor. Flash code should be 44. It covers about 5 different things