ECU still not reading coolant temp

My replacement ECU is still stating the “coolant temp insufficient for closed loop operation” my scanner sees it rise from cold to 185. I hate to just buy another sensor considering I can read it. Here’s the drawing. What would you look for? All grounds are fine.

 

Here’s my scanner . Any smarty pants out there?

 

When I disconnect the sensor it reads -40 so it has to be ok, where should I look now?!?!

 

I looked at a few wiring diagrams and they all show the same thing... part of the circuit for the ECT goes through the TPS. It sure sounds like the signal from the ECT is not getting to the PCM. I would disconnect all the connectors on that circuit and check for continuity, opens and shorts on the 2 wires that feed the ECT. As a final check follow the wire to the PCM and remove just that connector and see if the pin is bent. You might get lucky and by just reattaching the connector "fix" the problem.

 

P0125 is caused by a bad O2 sensor heater or its circuit. Always refer to the repair manual for the code to see what triggers the code.

 

No, you can still get a read off a bad thermister/temp sensor, however, if the OHM's are off, the temps the computer will read will be off also. All most temp sensors/thirmisters do is change resistance with temperature. To be correctly tested they should read a certain resistance [OHM] at a certain temp. If if doesn't, it's bad.

This is the same way you read appliance thirmisters/sensors in ranges and dryers, the read at a given temp must be correct or the computer board operates off false info.

 

You are absolutely correct. After spending six hrs looking at this, I discovered the shielded conductor in the four conductor front O2 harness had chaffed the top of the transmission shorting the grounded shield to the conductor within. Had to worm the harness out towards the drivers side to fix it. Thanks to who ever posted those links for the 2000 engine harness…. I was unaware anything was shielded till I saw the drawing. I assumed incorrectly that my scanner was being honest with me. Runs awesome now. Thanks

 

The scanner was honest in that it was the intended code. It's just Toyota uses that code for the O2 sensor heater circuit related problem. I'm not sure if that is a problem with language translation with Toyota engineers or what. The title of the code says "coolant" but the troubleshooting section only talks about the O2 sensor heater circuit. And they do this on other models too which causes confusion for people that don't go to the repair manual and try to diagnosis just from what the scanner says.