Mechanical Problems & Technical Chat - need some tech help

:(ok i've had issues for a period of time now with my cooling problem, i got this damn code (po117-engine coolant temperature circuit low input)i've done so much to try and fix it. cant tell what it is. i replaced the ect sensor, tried a different ecu, checked and tested the fuse and relays their all fine. my radiator fans arent kicking on, my a/c fan turns on like it is suppose to. my temp gauge works fine as well. just cant seem to put my finger on it. i've got a 97' civic ex 5-speed if you need to know the setup. input and suggestions would help since im stumped.:(

your coolant level isnt low correct? the thermostat could be stuck open, or shut... or have the wrong rating... have you changed your thermostat?

ya i replaced that to actually i replaced it twice to see if it was at fault,i also bleed the system and got the bubbles out. i also replaced the coolant sensors.the problem is electrical, think theres not enough voltage running through the wires is there anyway to up it?

Get a diagram (RonJ could help with that) and identify which pins on the ECU connect to the ECT sensor. Disconnect the battery, unplug the ECU and measure resistance between these pins on the harness plug. It should be the same as you'd expect to measure at the sensor. Which you can unplug the sensor and measure it and be sure it is as expected. If you find the sensor is OK but back at the ECU it's seeing the wrong resistance there is a problem with the wiring.

Edit: You did replace the right sensor, right? Should've been the one screwed into the head under the distributor with two wires. There are 3 sensors that measure temperature, only one of them feeds into the ECU and will cause a code though.

ORIGINAL: mk378
You did replace the right sensor, right? Should've been the one screwed into the head under the distributor with two wires. There are 3 sensors that measure temperature, only one of them feeds into the ECU and will cause a code though.


As mk378 says, there are three temperature sensors (see picture):

1) ECT gauge sending unit (dash gauge)
2) ECT switch (radiator fan)
3) ECT sensor (ECU) -- located just below the distributor next to the ECT gauge sending unit

http://img143.imageshack.us/img143/671/picture0419fl3.jpg

ORIGINAL: mk378
Get a diagram (RonJ could help with that) and identify which pins on the ECU connect to the ECT sensor. Disconnect the battery, unplug the ECU and measure resistance between these pins on the harness plug. It should be the same as you'd expect to measure at the sensor. Which you can unplug the sensor and measure it and be sure it is as expected. If you find the sensor is OK but back at the ECU it's seeing the wrong resistance there is a problem with the wiring.


Here is how to troubleshoot code P0117 (picture). If the suggested tests (some of which require a scan tool) don't reveal the specific problem, then I can post the mentioned ECU pin information.

http://img162.imageshack.us/img162/131/picture0421em4.jpg

thnx i needed those, now the thing with it also is when i unplug the ect switch for the radiator fans they still dont kick on nor when i turn on my a/c. you ronj can i get the ecu pin out diagram as well please it would help,i got a d16y8 with a ob2a ecu (p2p) 97' civic 5-speed.

Please clarify what you are saying. (1) Disconnecting the ECT switch should not cause the radiator fan to turn ON. (2) The ECT switch does not control the A/C condenser fan. (3) The A/C button does not control the radiator fan.

The pictures show that the ECT talks to ECM connector D at terminal 2.

http://img125.imageshack.us/img125/2932/picture0427az7.jpg

http://img125.imageshack.us/img125/2658/picture0428pv2.jpg

have you checked the fan motor? connect it to the battery and see if it turns on...