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Electrical harness from scratch?

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Old Nov 19, 2016 | 07:26 AM
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From: Ft. Collins
Electrical harness from scratch?

So recently rebuilt my engine, went to fire it up and long story short it started but the engine harness laid on the exhaust (DOH) and fried both the engine harness and the front chassis harness. I was curious if anyone has made a new, bare bones front chassis harness. I have a s4 n/a (my car is s5 though) engine harness which ive read can be used with a little work, but I cant find anyone to sell me or pull a front chassis harness to sell. My wiring skills are decent, but I'd like something to follow along with lol
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Old Nov 19, 2016 | 10:11 AM
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From: Mile High
Originally Posted by 94bajakid
I was curious if anyone has made a new, bare bones front chassis harness... I'd like something to follow along with lol
That "something" would be the wiring diagram in the FSM, wouldn't it?
If you keep the original switchgear and electrical devices, you're basically just duplicating the stock harness, that's the only way it'll work.
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Old Nov 19, 2016 | 03:10 PM
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i've done it, its a HUGE job, and unless you're changing the electrical system drastically; ie making it a race car. the benefits are small.

or to put it another way, unless you wanted to really change the switchgear, fuse box, stereo, pretty radically, then its not really worth the time.

the ECU/engine harness can be worth doing, as it is pretty well self contained, and when you upgrade ecu's you probably want to add more sensors

the charging harness is also a good candidate, as its small
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Old Nov 19, 2016 | 11:16 PM
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From: Ft. Collins
Originally Posted by j9fd3s
i've done it, its a HUGE job, and unless you're changing the electrical system drastically; ie making it a race car. the benefits are small.

or to put it another way, unless you wanted to really change the switchgear, fuse box, stereo, pretty radically, then its not really worth the time.

the ECU/engine harness can be worth doing, as it is pretty well self contained, and when you upgrade ecu's you probably want to add more sensors

the charging harness is also a good candidate, as its small
yeah the engine harness is no worries. I'm considering just wiring up the stock headlights, turn signals etc and have a super basic front harness. I can't remember what exactly crosses over from that harness to the engine harness off the top of my head though. I'm also worried about the damage done to the rest of the wiring under the dash, and relays and stuff. Might just buy a shell.
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Old Nov 20, 2016 | 10:04 AM
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From: Mile High
Nothing really crosses over from the chassis to the engine harness.
The engine harness does contain the wiper wiring but that's the only chassis related circuit.

My experience with our harnesses is that with a few exceptions (like injector pigtails) the wires are actually fine, it's the tape and other looming materials that get crusty and break.
Spend the time to deloom it and your wires are probably quite usable.

You'll also find a lot of unused wires (like for all the accessories you may not have or plan to delete) but don't automatically decide to rip them out.
Some of those circuits (like the AAS) can be repurposed to your benefit (I mention the AAS because it pops up at all four strut towers and is an easy way to get power/signals from the bay into the cabin, using wiring that's already in place).

You may be surprised when you remove the front harness that the longest wire in the whole car is the power feed to the washer bottle pump.

Just a bit of trivia.
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Old Nov 22, 2016 | 11:12 AM
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From: Ft. Collins
Originally Posted by clokker
Nothing really crosses over from the chassis to the engine harness.
The engine harness does contain the wiper wiring but that's the only chassis related circuit.

My experience with our harnesses is that with a few exceptions (like injector pigtails) the wires are actually fine, it's the tape and other looming materials that get crusty and break.
Spend the time to deloom it and your wires are probably quite usable.

You'll also find a lot of unused wires (like for all the accessories you may not have or plan to delete) but don't automatically decide to rip them out.
Some of those circuits (like the AAS) can be repurposed to your benefit (I mention the AAS because it pops up at all four strut towers and is an easy way to get power/signals from the bay into the cabin, using wiring that's already in place).

You may be surprised when you remove the front harness that the longest wire in the whole car is the power feed to the washer bottle pump.

Just a bit of trivia.
Thanks for the info! Yeah, I would like to reuse as much as possible but there is 6in of the bundle that smoldered together from frying my options are either run all new wire and Repin everything or maybe get lucky and cut that section out and splice in wires. Either way it's going to be a lot of work lol.
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Old Nov 23, 2016 | 09:16 PM
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Ive done it to 60% of my loom.

If I was to do it again id do a http://infinitybox.com/
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