# rb20det coolant sensor pin problem



## hadyedar (Dec 31, 2015)

hi all..can someone tell me which one is positive and negative pin for water coolant sensor unit..at the connector..theres two wire 1 is green/yellow and other is black i guess green/yellow is positive and black is negative rite?the problem is the harness connector is rotted n broke,im still using original first generation rb20det wiring(jdm cefiro A31)..so i dont know which one to connect with..its different a bit from later rb series..normal ''female'' pin theres a grove at middle but this one grove at the left not middle..so which one to positive and which one for negative?


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## keithmac (Mar 1, 2014)

It doesn't matter, it's just an ntc resistor inside (not polarity sensitive).


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## hadyedar (Dec 31, 2015)

thanx for the info..about 6 month ago my car cefiro a31 rb20det suffering fuel pump problem..before check internal fuelpump i suspect faulty aacv also can cause engine stall at below 2k rpm and while brake for traffic light. that time i use internal fualpump and external pump with catch tank..after change new internal fuel pump i want to quick check-up so not connect through catch tank,i directing internal pump pipe to external fuelpump pipe..by pass catch tank..engine run ok at idle..after warm-up i revving 4-5k rpm,sudently engine sounds like using highcam burp burp burp burp..cannot rev above 4rpm at all..im sure suspect both fuelpump because internal pump and external pump different pressure,maybe internal fuelpump pressure lower than external(high pressure)..looks like i need to hard-working not lazy..heh


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## hadyedar (Dec 31, 2015)

keithmac..have you see or heard rb20det water temperature sensor harness to ecu bypass using a relay,injector ground and 1 more(not remember).normaly water temp sensor wire direct to ecu socket but my frend coolant temp sensor wire through relay socket then to ecu..2 more i not remember..there are 4wire =1)green/yellow(coolant sensor) wire from engine.2) green/yellow(coolant sensor) wire from ECU pin 28...another 2 i not remember..i check it later..all 4 wire use 1 relay..its all connected..for what purpose..try asked your frend ok..


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## hadyedar (Dec 31, 2015)

hi keith..my previous owner install a relay from coolant sensor ecu pin harness to ecu..can you tell me why?whats the purpose?


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