CTS wire voltage?

[beamer1341]

So i was playing with my multi meter today and found I only have .5v to the CTS when haynes says it should be ~4.5v
Any Suggestions to solve this?
Thanks Branden

 

[luv2rallye]

For the 2 wire CTS, 0.5v would be correct if the water temp was 176*F (it having 296 +/-32 ohms). At 68*F it should have 2.45k +/-0.24k ohms. Measure its resistance - it's probably bad. If ok then suspect ECU.

 

[beamer1341]

I checked the sensor its has resitance within range but according to my haynes the harness/vehicle side should have app 4.5 volts with key on. I only have .5 but I've never really like haynes manuals but it came with the car so...

 

[g4ebguy90]

Are you testing the harness itself? One wire should be the reference voltage, and the other that actually gets back to the ECU to determine coolant temperature. I would say you are testing the return wire, not the reference. The manual probaly says you will have a 5 volt reference.

 

[luv2rallye]

Actually the green-black wire is an internal ECU ground while the yellow-green is the sense wire which has an internal pullup to 5v. So if not connected the harness will read 5v on the sense wire. But when connected the resistance of the ECT sensor acts as a voltage divider so the voltage across it will be between 0 - 5v depending on its resistance (which is inversely proportional to its temperature).