Hey all,

So, my coolant temperature gauge hasn't worked ever since I got my truck in May. (2005 3.0 Edge, 2wd) I finally got around to doing what I assumed was the cause - the gauge temperature sending unit. I replaced that, plugged it in, fired her up -- and the gauge stayed firmly below the bottom of "Cold" even after driving for about 10-15 minutes at higher revs. I don't have any electrical knowledge, though my brother sort of does (so I could ask him for help if necessary). What should my next step(s) be?

Any suggestions appreciated! Thank you for your time.

 

There are TWO coolant temp units on your engine
1. ECT sensor, 5volt, only used by the engine computer(PCM), many replace this one by mistake

2. Coolant temp SENDER, 12volt, only used by the dash board temp gauge
Sender should have a red/white wire and a black/white wire
If you Ground the red/white wire, and turn the key on the temp gauge should go up to HOT, full HOT, this tests if red/white wire and gauge are working, this should happen if wire and gauge ARE working

Now put a jumper wire between the red/white and black/white wires, black wire should be a ground, turn key on again, should go to full HOT, that means black/white ground wire is good
If you replaced the correct SENDER then take it back its bad

These units "look the same" but are not, one uses 5volts and the other 12volts, and they use different resistance as well
Most auto parts stores will sell you a SENSOR first, so make sure you ask for a temp S E N D E R

 

Thanks very much Ron! The sender has the cylindrical head, not the conical one, right? I replaced the cylindrical one, and put it on the clip with the red-and-white & black-and-white wires. I'll try your suggestions and go from there. Thank you very much!

 

Yes, correct, cone shaped end is usually ECT sensor, cylinder shape is sender

 

Thanks again! I haven't had a chance to poke around yet, but I will.