water temp sensor rewire

[banishedmunk]

i am needing to rewire my water temp sensor to the ecu but i am unsure of where to run the wires i know that pin 20 is for the coolant temperature sensor and that pin 24 is the sensor ground what i am unsure of is which wires need to go where or does it even matter any input would be greatly appreciated

 

[mach4g63t]

Run a continuity test on the wires. Use a multi meter and hook the end of one wire to one side and the other to the pin on the ecu. If there is continuity then the multi-meter should beep and show a current. Then route the wires the same way and you wont have to worry about it.

 

[luv2rallye]

The sensor wires do not have polarity if that's what you're asking so it can go either way. Just make sure the sensor ground goes to ECU pin 24 (or another sensor's sensor ground) - not to chassis or engine ground or you can get misleading and noisey signals.

 

[banishedmunk]

there are two spade connections on the sensor which one is for the ground wire

 

[banishedmunk]

ah i understand now it doesnt matter which one goes to the ground as long as one of them does?

 

[tqmx1]

^^^

 

[banishedmunk]

thanks for the help

 

[somdturbo]

The sensor wires do not have polarity if that's what you're asking so it can go either way. Just make sure the sensor ground goes to ECU pin 24 (or another sensor's sensor ground) - not to chassis or engine ground or you can get misleading and noisey signals.

Bringing this back a little bit.

I have been working on my car and we were having trouble starting it. After about 30 minutes of cranking and sputtering, it started. Acted just like the coolant temp sensor was bad. Sure enough, the wires were broken. I crimped new terminals on the wires, reconnected them and still no dice. We did a continuity check from pin 20 to sensor power, and that was fine. Then we did a continuity test from pin 24 to the sensor ground wire, and there was no continuity.

Under further investigation, it appears as if ecu ground (pin 24) is connected to chassis ground, should this be that way? while ohming out pin 24 I accidently touched the engine itself and realized the continuity between the two. I see you mentioned that the sensors need to be grounded to the ecu not the chassis, could this cause mulitple problems? The car is running like shit....

 

[luv2rallye]

On a 1g the engine coolant temp sensor's power & ground are ECU pins 20 & 24. On a 2g they are pins 83 & 92 (note: on some 2g diagrams pin 92 is incorrectly called ignition switch).

ECU sensor ground (1g pin 24, 2g pin 92) is connected to chassis ground INSIDE THE ECU and all the sensors grounds MUST be connected to ground through this ECU pin ONLY to prevent ground loops and noise from affecting the ground signal. Connecting any one of the sensor grounds to chassis ground other than here will affect all sensor grounds (since they are connected together) and can/may make the entire engine run crappy due to noisy signals or ground loops in these grounds. If you want to check if any of the sensors grounds are incorrectly connected to chassis ground other than here, just unplug the ECU connector that has the sensor ground pin (1g pin 24, 2g pin 92) and then check sensor ground continuity to chassis ground.