Engine Coolant Temperature Sensor wiring question

[Guanfy]

I'm replacing my ECT with a Motorcraft one but I have to replace the pigtail for it as well due to the original wiring being bad. My question is that the wire colors used on the pigtail don't match the ones coming from the wiring harness. Is there a way to tell which wire I need to soldier to what to make sure the sensor will work as intended? I'm using the pigtail made by Standard and the wire colors are green with yellow stripe and black with white stripe.

 

[91stranger]

The plug will only go on one way so you can match up which wires are going were on the old plug. Shouldn't be that hard once you hold the two side by side. I think you are over thinking this. It's just 2 wires.

 

[Curious Hound]

It doesn't matter. The ECU is just reading the resistance of the sensor.

 

[Curious Hound]

The plug will only go on one way so you can match up which wires are going were on the old plug. Shouldn't be that hard once you hold the two side by side. I think you are over thinking this. It's just 2 wires.

He's replacing the pigtail. Still doesn't matter.

 

[Guanfy]

If I had a picture of the original wiring you would be 100% correct... but I don't. Someone already swapped in an aftermarket setup when I got the truck.

 

[Guanfy]

It doesn't matter. The ECU is just reading the resistance of the sensor.

That is welcome news indeed. If the new sensor and pigtail don't resolve my issue, the hunt continues..

 

[91stranger]

What is the issue? The gauge on the dash not showing any reading? Don't over-do the Teflon tape if you use Teflon tape. You have to make sure some of the threads on the ECT sensor are making contact with the block or else it won't give any reading since it's not grounded.

 

[Guanfy]

Issue is the truck is running rich with rough idle, reduced fuel economy and most likely reduced power. I have a check engine light that will flash for 10 seconds or so then go away every now and again. If the ECT is bad, it can cause lean or rich conditions. The spark plugs and wires are new, the fuel injectors are new so I don't suspect them. I've heard the ECT really needs to be the motorcraft one and is a bit fiddly that way. I currently have one from standard in there. If this doesn't cure it I'm going to check the air charge sensor, MAF and o2 sensors. Just working my way through the list of potential culprits until I solve this. I brought this truck back from the grave with it being completed broken down. Terrible financial decision but the end is finally in sight. Just need to finish it out now.

 

[Dirtman]

What is the issue? The gauge on the dash not showing any reading? Don't over-do the Teflon tape if you use Teflon tape. You have to make sure some of the threads on the ECT sensor are making contact with the block or else it won't give any reading since it's not grounded.

ECT sensors don't control the temperature gauge, nore are they grounded by the engine.

 

[Curious Hound]

What is the issue? The gauge on the dash not showing any reading? Don't over-do the Teflon tape if you use Teflon tape. You have to make sure some of the threads on the ECT sensor are making contact with the block or else it won't give any reading since it's not grounded.

You're confusing the temperature sender (one wire and a grounded body) and the ECT sensor (two wires, not grounded to the block). The sender operates the gauge in the instrument cluster. The sensor sends info to the ECU. He's not having monumental problems here. Just needs to replace the pigtail on the wiring harness. The original question has been answered.