Grounding Sensors to chassis, 12v to sensors on own circut. Bad idea?

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illwillem
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Grounding Sensors to chassis, 12v to sensors on own circut. Bad idea?

Post by illwillem » Fri Aug 28, 2015 12:02 pm

Looking for an answer about grounding the TPS, AT and ECT sensors...

I bought an OBD1 b18 swapped crx with a stripped down harness IE nothing but the sensors to the ECU, no relays or anything like that..

The PO had the MAP, TPS, ET, all grounding at (OBD1) pin D22

then he had TPS, MAP getting power from D19.

My question is this, Does the ECU use the grounding signal to turn on/off the sensors? I'm doubting it because they have all been ganged to the same ECU pin, which is outside of factory spec. I'm looking to have them ground to chassis via Deutsch connector to BUS so I don't have to splice wires together in the new harness.

Same with the 12v power for the sensors, obviously the signal wires will go to ECU as well as power wires for sensors that have provisions, but for the others I was going to put them on their own 7.5 amp circut that turns on at the same time. Would this be a bad idea. I feel like ganging them into the same PIN(s) on the ECU side the way the PO has it is a way worse idea.

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Re: Grounding Sensors to chassis, 12v to sensors on own circut. Bad idea?

Post by Hondata » Fri Aug 28, 2015 2:49 pm

You MUST copy the factory harness EXACTLY. By changing the ground location for sensors at the very least you'll create ground loops - the factory harness grounds the sensor back to the ECU to prevent this. Also by sharing grounds for multiple sensors the current flow through one sensor will affect the other sensor. eg if your MAP changes then the TPS signal will change a little too, even if the sensor has not moved. Honda does shares the grounds for the IAT, ECT, TPS and o2 signal, but they are all low current inputs.
MAP +5V should be D19, but TPS +5V should be D20. Be careful as giving these sensors +12V will not be good for them.
Likewise MAP ground is D21 but TPS ground should be D22
Again, copy the factory harness exactly, including the shield wires.
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illwillem
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Re: Grounding Sensors to chassis, 12v to sensors on own circut. Bad idea?

Post by illwillem » Fri Aug 28, 2015 4:54 pm

Got it, and thanks for the detailed reply. I'll copy the harness exactly where the OEM pin provisions allow.

Would you be able to tell me how many volts the IACV is looking for? Its the only one left that has no where to go for power. Its on a type R intake mani so im assuming its the shorty IACV (if that makes a difference.) Ive been looking at the factory schematic an it only shows one side to A9 and the other going into the "Junction connector".

Current wiring set up has the injectors 1-4 and the IACV splicing together into a 12v source.

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Re: Grounding Sensors to chassis, 12v to sensors on own circut. Bad idea?

Post by Hondata » Fri Aug 28, 2015 4:56 pm

The IACV goes to the same +12V supply as the injectors, which is switched by the main relay.
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illwillem
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Re: Grounding Sensors to chassis, 12v to sensors on own circut. Bad idea?

Post by illwillem » Fri Aug 28, 2015 5:07 pm

Awesome, ill just clean it up then. Thanks again for your help

illwillem
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Re: Grounding Sensors to chassis, 12v to sensors on own circut. Bad idea?

Post by illwillem » Sun Aug 30, 2015 4:35 pm

Would you be able to tell me what the part number is for the crimp on wire ends that insert into the plug ends (female) of the sensors. I know that the Dizzy has 2 different sizes but I already have the bigger set as they came with my CPR Kit. Im just looking for the other size wire ends so I can finish rebuilding my new harness with the above mentioned sensors.

Also, do you happen to have the part number or source for the injector pin wire ends too? Thanks!

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Spunkster
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Re: Grounding Sensors to chassis, 12v to sensors on own circut. Bad idea?

Post by Spunkster » Mon Aug 31, 2015 11:54 am

I'm sorry, but we don't have part numbers for all the different pin types used by Honda.

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