1996 FLD120 what is this

In the ECM with a laptop or ProLink, you can set it to shutdown, or for it give you a warning light.

Sounds like it's set to shut down. You can just reprogram it to warn. Takes seconds.

But, an electrical fault usually won't cause a shutdown. Are you sure coolant level is the problem? If it's unplugged, you should get a fault for coolant level sensor input voltage high, causing a check engine light, but not a shutdown light.

Have you flashed fault codes? Are you getting a red code 43?

 

My suggestion to twist wires together was only meant to temporarily see if it fixes the problem. I’ve done it when my harness plug at the sensor was bad.

 

I'd flash the fault codes, see what comes up. Red flashes are shutdown faults, yellow are warning

 

I thought maybe you had a ddec 2. It has a module. Chances are you have a ddec3 No module.

 

If there's an override button, hold it for 3 seconds with key on

 

Only ddec2 has it. I think you have ddec3. Compare your ecm with pictures I posted.

 

It is a DDEC III. You can see the Intake Air Temp Sensor here.