2004 d2 f 4.6 with SAI....reshly rebuilt. ECT goes up during check but then drops to -40 ...and scanguage says the same. tried a new sensor but no luck...checked wiring....no luck... please help me with some diagrams or something to just run new wires if i have to....losing my mind over it!!

 

Could have a bad sensor out of the box.
Hope the electrical schematic helps identify where it goes into the ecm

 

Just curious. What do you mean by, the ECT goes up during check?

 

when you start car and all guages get power it goes all way up and then drops down below cold and stays there

 

i have a brand new sensor and then also tried a used one that was working.... no luck... im thinkong run new wires from ecm and see what happens...thank you

 

Okay, so the gauge is operable. You can try unplugging the sensor. Then connect a test light between the two terminals on the connector. The temp reading should change. If it does, the sensor is no good. If it doesn't, one of the wires may be broken.

 

so.... ran 2 new wires to pin 21 and 22 to ECM and still no action on the gauge....but i do have almost 5v now which i didnt have before...ugh.... whats next? bcu?? bad gauge??

 

Have you checked the temp with a scan tool? If the temp seems right on the scan tool data, you may have a problem with the cluster or the stepper motor.
I almost forgot. If you don't have a code stored for the ECT sensor circuit, the computer is most likely seeing the correct temp.

 

i have an ultragauge and it reads -40 so must not be getting any info.... there is a code.... p0117

 

Have you tried connecting a test light, in series, between the two terminals on the connector? If the temp reading changes when you do that, the wiring and ECU are good. Meaning it's just the sensor. If not, it could be a pin fitment issue, corrosion in one of the connectors or something wrong with the ECU internally.