Should this thing be unplugged?

New (to me) M1152A1, this thing is in the engine bay, right in front of the driver. It's been unplugged since I got the truck. Google says it's a 'time delay module' for the cooling fan.

Truck seems to run and drive fine. Should I leave it unplugged or plug it back in?

It should be plugged in otherwise the fan will operate constantly leading to slower acceleration, more wear on components, worse MPG, and other issues.

You need to test/troubleshoot the fan system, it is likely it was unplugged because there is a problem causing overheating.

Ok, I did some more reading and have a good idea how to test the system.

On a related note, why is there what appears to be clear silicone gooped on various hose fittings? I thought maybe it was just some shade tree stuff going on with my truck but I see it in pics of other trucks too. See the hose attached to the gold colored Cadillac valve...

matt2491 said:

Ok, I did some more reading and have a good idea how to test the system.

On a related note, why is there what appears to be clear silicone gooped on various hose fittings? I thought maybe it was just some shade tree stuff going on with my truck but I see it in pics of other trucks too. See the hose attached to the gold colored Cadillac valve...

Click to expand...

.
Sealing out the weather...
The USMC coats everything in clear silicone.
Other branches do as well - for protection from sea water.

I have the same truck. So plug it back together and start the truck and rev it. If it sounds really loud like a big fan blowing than something isn’t working correctly. For me it was the thermostatic switch on the water crossover pipe thing. If yours isn’t working I would start there. So the switch can be either stuck so the fan is always on. Thus engine stays cooler all the time (kinda sucks in the winter) or it stuck so it never comes on.

If you plug it in and the fan isn’t crazy loud then take it for a rip down the highway to get it hot. On my gauge it gets to approximately 250 before the fan kicks in. When my switch wasn’t working the fan never came on and it started to get to hot and steam everywhere. Pull over in the BDL and let it sit for a little bit and unplug that connection in the picture. Then start it up again and the fan should default to being on all the time. You can drive it like that but it’s not ideal.

Also when the fan is on all the time the temp gauge rarely ever registered. I thought the gauge was broken but it was just the fan was always on.

There are a couple videos on YouTube on how to bench test that switch by heating the switch up and testing continuity to see if it is working correctly at different temperatures.

The temp switch is easy to verify, if everything is plugged together and the fan does not run when cold, unplug ether wire going to the temp switch and the fan should run (fan runs when switch is OPEN) if all that checks out then the "system" is working, then if the fan does not run when hot (240 or so) then the switch is bad.
If the fan runs when the engine is cold then ohm the switch and if it is around 0 ohms then another component is probably the issue, you can also short the two leads coming from the harness (458B/D) to the switch and the fan should not run.
The fan switch is in the drivers side of the water crossover with two individual leads. (with wire tags 458x)

I will try these things when I can get the truck out on the road!

Did you see the pm I sent to you?

Yes, thanks! I had watched that video and have some ideas to try. Here it is for anyone else:

The best fix is going to a viscous clutch fan, best upgrade I ever did to the truck

Finally got a chance to take the truck out and drive it around some. I plugged the module back in while it was running and immediately noticed the fan got quieter and appeared to spin slower. So something is working, though I haven't tested the whole system to the fullest extent. But I'll leave it plugged in for now and check it out more later on this spring when the weather warms up.