Jeep grand Cherokee Overland 4.7 engine coolant temperature sensor

Hello, new member here.

Kind of a long story but will try to give you the condensed version. I bought the car with a blown motor, did a rebuild on the 4.7 got it running. On start up noticed the fan was running at full speed at idle. Also alt was not charging, the code was p0017 or low voltage at coolant temperature sensor. I started chasing down wires and found the pin on the ecm for the engine coolant temperature sensor had no power.I figured must be the ecm so I replaced that, however nothing changed still no power at cts pin. I went through the grounds they are all clean and tight, tried even running new grounds to the ecm/bcm nothing. I tried the reset ecm numerous times still nothing.  The next thing I'm going to try is to have the ecm programmed without the skim as a last resort. Ha- ha this was supposed to be a easy project! Might have bit of more than I can chew. Lol.

Update: Previous owner had the engine coolant temperature sensor and the alternator connectors reversed! That was corected but now a new problem reared its ugly head, the motor will start but quickly die. The skim light is not lit and there are no thrown codes.This leads me to think it's a fuel problem, the fuel tank has been drained and flushed the fuel pump is priming when key is on and all fuses are good & all sensors have been replaced???
Anybody have any ideas?

Welcome to the forums!

No offense, but are you sure you got that code right? Because P0017 is a Cam/Crank Correlation code. If you're sure that's the code you pulled, then you may be dealing with a timing problem as well as an electrical issue. Unless you meant P0117, which IS an ECT code.

Do you recall which wire you were testing for the ECT, exactly? I can find it on a diagram if you know the color and pin #.

When you took 'juice' from the MAP, does that mean you borrowed 5V from the MAP and connected it to the ECT? If so, undo that. :silly: 5V circuits cannot be shared between thermistors and pressure sensors/potentiometers, and may be related to your crank/no start.

Please answer the above and we can help you further.

Hi Tyler thanks for reply, sorry the code po117. Also the wire color is white w blue tracer. As for the pin it is # 25 left side grey ecm connector. Oh dont worry not taking power from Map sensor anymore! Mech not my main job (thank god!) Let me know if you need anymore info.

Thanks for the quick answer! I forgot to ask earlier. :blush: What year is your Overland?

I ask because I'm trying to match up those pins with the right wiring diagram. I took a guess at an '04 and missed. :lol: Does the engine now start and run with the MAP 5V jumper removed? With the new PCM, is the P0117 still current?

Sorry still trying to figure out this site. I would really like to attach a photo of the wire and pin. The problem still persists, hope to get new ecm soon. Removed the 5 volt jumper wire from map sensor no change. My battery just took a dump, best change it out before getting the new ecm. The joys of owning a Jeep!