# Obd II signal ground???



## crustysack (Oct 5, 2008)

Does anyone know exactly where to hook up the OBDII wire (pin#5) that is the ecu ground/signal ground. Right to the ecu? the motor? the same ground the ignition relay is grounded to? any help appreciated


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## 05GTO (Oct 6, 2004)

Any chassis or body ground will be ok, here is a schematic; 

http://www.obddiagnostics.com/DataSheet.pdf


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## crustysack (Oct 5, 2008)

pin#2 is data, pin# 16 is +12v, pin #4 and pin#5 are both grounds can i hook them both to the same ground point? ( the schematic is french to me) thanks


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## Poncho Dan (Jun 30, 2009)

I hope you're not intending to ground your wideband to the OBDII ground... It'll give you signal noise... just a heads up.


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## crustysack (Oct 5, 2008)

??? what is the wideband?? I am just trying to figure out how to hook up the obdII port on this ls1 (2002). so i need 2 separate ground points?? one for pin#4 and one for pin#5? and whats the best place for them


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## Poncho Dan (Jun 30, 2009)

Oh, I thought you were in the process of tuning, nevermind. I would wager any chassis ground would work, and probably separating the 2 grounds wouldn't be a bad idea, and if anything, the motor makes for a great ground.

Actually I bet if I go out and look, the grounds probably just connect under the dash somewhere, maybe to the steering column or something.


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## 05GTO (Oct 6, 2004)

It is my understanding that only pins 2, 5, 7 (ISO 9141 only), 10 (for Pwm which is ford) , 15 (ISO 9141 only) and 16 are used on the OBD-II (only 3 pins used on GM) and if you have instructions stating 4 is a ground then you can connect it with pin 5 to the same ground. ISO 9141 is used on Asian & European vehicles.


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