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Old 02-20-2015, 12:11 PM   #1
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Default IAT wire gauge question

I feel dumb asking this but so goes my ignorance. I need to create a pigtail for the GM IAT sensor to splice into the stock harness for a MS2 on an 04' MSM.

What gauge wire is that OE line? I am assuming that since it is low voltage I really want to have the same wire diameter and length to keep impedance as close to stock as possible.

Thanks.
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Old 02-20-2015, 12:39 PM   #2
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wire. use wire.
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Old 02-20-2015, 12:56 PM   #3
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Quote:
Originally Posted by Braineack View Post
wire. use wire.
Coming from you, based on the 1000+ responses from you I have read in all my research on here that means:

"If the wire gauge is close to the OE lines it should be fine."

Did I get that right?
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Old 02-20-2015, 01:09 PM   #4
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Let's assume there is 10 feet of wire from your iat to the ECU.

using 20 gauge wire that's 0.20 ohm of resistance (2 wires x 10 ft leads *.01 ohms per foot).

your IAT sensor has 560 ohm to 7000 ohms operating range.

at 560 ohm or that .2 ohm increase changes your reading by .03%.
at 70000 ohms it's 0.003% change.

So TLDR wire resistance is relatively negligable in an IAT sensor reading for the usual automotive wiring gauges. Just don't use a 40 gauge wire.

American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies and wire breaking strength
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Old 02-20-2015, 01:16 PM   #5
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I've always just used whatever similarly sized wire I had laying around, then stuffed it in my bunghole and the readings have seemed to be pretty accurate.
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Old 02-20-2015, 01:26 PM   #6
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plus you calibrate the sensor so it doesn't matter.

you could install a 1K resistor inline...
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Old 02-20-2015, 04:46 PM   #7
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Thanks, y'all. The calibration will be fine with the MS2, but I will be needing to put the stock IAT back on every two years to pass emissions so I need things running without CEL prior to turning/calibrating the MS.

All that has been said makes sense. Wiring is a whole new world for me; steep learning curve.

Cheers!
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