Engine Harness Tucking, Sensor reliabiity issues, electrical resistance issues.
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Engine Harness Tucking, Sensor reliabiity issues, electrical resistance issues. Id like a few opinions on the following. Ok so I am extending or shortening an existing lq9 engine harness for aesthetic reasons. Instead of cutting the wires into two pieces and soldering a length of wire into the cut two sections of wire, I went to auto part recycle yard, and dismantled a 98 Silverado wiring harness and separated all the wires that had pins on them in hopes of just having to do one joint/soldering spot per wire that needs to be modified. I went home and compared the existing lq9 harness with the wires I pulled at the junk yard, the lq9 wires appeared to be a thicker gauge with 7 thick strands. The junk yard wires are thinner gauge with thinner seven strands. My concern is having to much resistance in the circuits, in turn adversely affecting the sensors/injectors or the pcm in a negative way. Can I use the wires I pulled from the yard even though they are not the same gauge or will I cause electrical issues ? The girth of the wires are, .066 and .077, .077 being the lq9. I made a soldered connection using the different wires and measured the resistance, the meter showed 0 ohms. Another question would be why does the lq9 engine harness have different size wires for different components. What's the purpose of different gauge wires ?
Last edited by Lq9'ed 80 Sierra; Apr 13, 2014 at 07:32 PM.
man at the low voltages most of the sensors run at, resistance from extra wire or a couple solder connections ain't really gonna be an issue. bigger issue is crappy joins or not using adhesive backed heat shrink to seal it from corrosion.
make your splices like the GM splice packs. totally water proof.
make your splices like the GM splice packs. totally water proof.
you won't have any problems. with copper prices continually going up, you'll find later model years have much thinner wires all around (less copper = less cost).
the old rule of thumb of how much amperage a certain gauge wire can handle per length has been overally conservative for years, you can put a lot of current on 18 and 20 gauge wires. the resistance in ohms for a thin 20 gauge wire is about 10 ohms but for 1000 feet of wire, so only about 0.1 ohm per 10 feet. with 10 amps on that 10 foot wire you would have about a 1 volt drop which is not a problem in a 12vdc system for most loads. regarding computer equipment, those aren't high amperage loads, they are not even over 1 amp most of the time so if you do the V=IR math it's no where close to being a problem. i would only be concerned about using a wire in the harness which is thin for some other purpose than it was intended- if you used it to power the relay for your fuel pump or headlight then you would have a problem.
http://en.wikipedia.org/wiki/American_wire_gauge
the old rule of thumb of how much amperage a certain gauge wire can handle per length has been overally conservative for years, you can put a lot of current on 18 and 20 gauge wires. the resistance in ohms for a thin 20 gauge wire is about 10 ohms but for 1000 feet of wire, so only about 0.1 ohm per 10 feet. with 10 amps on that 10 foot wire you would have about a 1 volt drop which is not a problem in a 12vdc system for most loads. regarding computer equipment, those aren't high amperage loads, they are not even over 1 amp most of the time so if you do the V=IR math it's no where close to being a problem. i would only be concerned about using a wire in the harness which is thin for some other purpose than it was intended- if you used it to power the relay for your fuel pump or headlight then you would have a problem.
http://en.wikipedia.org/wiki/American_wire_gauge
