1996 FLD120 what is this

Unless it has a Kysor or some other aftermarket engine shutdown,then the coolant level sensor should go to the ECM.
@Big Road Skateboard @Rideandrepair

 

Possibly some sort of flasher? I've never seen anything like that one inside an FLD fuse panel. I see it's vented though. Maybe an alarm speaker? If you can still see the wire #'s, you can cross reference those in the book.

 

Maybe a converter of some sort. Used with LED lights. Without it LEDS won’t work right???

 

Forget about it!! What’s up with the coolant sensor?

 

It's been a long time since I've worked on one, but many FLD's had a Coolant Level Sensor Module. Kinda like a fan stat maybe? IIRC? It's been forever and I hate to say for certain. I do remember they had 4 or 5 different inputs.

I only know about them because I've had fan control issues and other intermittent problems that I traced back to these modules being shorted out inside.

Maybe the OP can post a pic. They're listed on the box.

 

IDK, but it looks like it goes into some factory wiring.

 

Low air buzzer added after the original buzzer failed?

 

My 2000 has a power distribution module, It’s located in the same area. It replaces 4 sensors. It’s twice the size, and marked pdm. My 99 didn’t have one. I’ve had many problems with the coolant sensors, especially on my current 2000. The fix is usually the sensor itself. However, once it was the wire/pigtail. The wires break along the valve cover. Common problem. I had an intermittent problem for years, till I changed the pigtail. They sell it with about a foot of wire attached. I only cut about 8” off my original harness. Leaving room for error, not knowing exactly where the original wire was broken. Before that, it would shut down every time I washed the Truck. Also during heavy rains. I’d unplug it, till it dried out, usually about a hour down the road.it would shut down again. Then have to plug it in, till it got wet again. It drove me nuts, for a few years. Changing sensors, 3-4 times before finally figuring it out. That’s the only sensor I’ve ever had a problem with on both my 12.7 s. It’s common. Old ones had to jump the plug. A paper clip was typically used. Newer ones, after 2000. Simply unplug the sensor. Paperclip jumper only needed to turn off CEL light. I don’t know of any module specific for the coolant sensors. PDM controls fan causing it to act erratically. Another common problem. Both my Trucks had that issue with and without a Pdm. Fan kicks on sometimes in cold weather, more often when coming to a stop, for no apparent reason. Both issues are minor aggravations, compared to newer engines. Some more research needs to be done if this is a problem. I think it’s a Freightliner issue, more so than Detroit.