Coolant Gauge not working, engine running rough

[Expensive_Habits]

Truck: 1994 K1500 5.7L 4L60E 4x4

I need some serious help. Obviously I would go to a mechanic if I had the money but I simply don't at this moment.

My K1500 is having a lot of issues related to engine performance and pretty much everything wrong can be roughly traced back to the engine coolant temperature sensor. I have come to realize that there are two different sensors: one on the intake and one between two of the spark plugs on the driver's side of the engine.

Everything seemed to be in order at first glance. And not knowing much about cooling systems or electronics. I replaced my thermostat just to be safe, being that I had no idea how old it was. When I took the thermostat out the O-ring crumbled when I pushed on it... so it's safe to say that it was fairly old. But when I replace the sensor I realized that it doesn't have any wires coming directly from it so it is mechanical and while a faulty thermostat could still definitely affect performance... it wouldn't really have anything to do with the gauge not working whatsoever. Or at least that's what I figured.

After some further investigation I found out that I had made a major oversight... the sensor that is located between the spark plugs, has two wires on the plug. I somehow missed that one of them is completely severed. The problem is, I have no idea where the other half of that wire is or where it plugs in. Does it plug directly into the ECM? Or is there a different location i should be looking for this stray wire??

From what "research" I have done in the forums and on ShopKeyPro: I have figured out that the plug that I'm referring to is indeed the one that gives the signal to the gauge.. but I worry that the wire is cut at a point that there may be no signal going to the ECM, let alone the gauge. I'm not really sure where to go from here and if somebody could take pictures of their wiring going from that specific sensor to whatever location it's supposed to go to I would greatly appreciate it.

 

[Schurkey]

Truck: 1994 K1500 5.7L 4L60E 4x4

My K1500 is having a lot of issues related to engine performance and pretty much everything wrong can be roughly traced back to the engine coolant temperature sensor.

I have come to realize that there are two different sensors: one on the intake and one between two of the spark plugs on the driver's side of the engine.

The one in the intake near the thermostat (two wires) will affect engine operation. The one in the cylinder head on the driver's side (one wire) affects only the dash gauge.

But when I replace the sensor

WHICH one? The sensor by the thermostat, or the sending unit in the cylinder head?

I realized that it doesn't have any wires coming directly from it so it is mechanical

There's no mechanical temp sensor on that engine. If there's a temp sensor with a capillary tube, someone added it and it would go to an aftermarket temp gauge.

The computer sensor has two wires. If the sensor has no wires, you need to locate them and plug 'em into the sensor.

the sensor that is located between the spark plugs, has two wires on the plug. I somehow missed that one of them is completely severed. The problem is, I have no idea where the other half of that wire is or where it plugs in.

The sending unit in the cylinder head has ONE wire that controls the gauge. There may be a two-wire molded-plastic connector, but only one wire actually attached. There was a photo of that posted here, recently, but I'm too lazy to go looking for it.

if somebody could take pictures of their wiring going from that specific sensor to whatever location it's supposed to go to I would greatly appreciate it.

YOU need to post photos--in focus, nicely cropped and resized--of the "mechanical" temp sensor, and the area around the thermostat housing where the coolant temp sensor for the computer should be.

 

[Expensive_Habits]

There's no mechanical temp sensor on that engine.

The one in the cylinder head on the driver's side (one wire) affects only the dash gauge.

That's the one!

 

[Expensive_Habits]

There's no mechanical temp sensor on that engine. If there's a temp sensor with a capillary tube, someone added it and it would go to an aftermarket temp gauge.

I was referring to the thermostat, not a sensor, and my newbie self not realizing that the thermostat has nothing to do with the gauge. When replacing it, i came to the realization that "sensors" exist. Like an idiot.

I was essentially just saying i'm new to this and didn't need to replace my thermostat.