Electrical Harness replacement - $5,600??

This sounds like they have not got a clue what is wrong. Generally speaking wiring harness do not completely fail one wire might go open circuit or short to chassis (ground).

First port of call check the 12v battery and report back.

A complete failure mode would be a short circuit that burns through the harness or loom (as we call it in the UK) but if this happened you would know from the smoke and fumes.

A single wire failure should be able to be fixed by any self respecting auto electrical engineer.

 

Sounds like an incompetent technician. I also agree that it's likely one failt in the entire harness. Two or more problems can happen, but not very likely,

 

Yeah, check that +12 volt battery, that's number 1. Do you have a record of the codes thrown? That might point to a specific wire circuit if indeed there is a "Wiring Harness" problem.
It's like ripping out and replacing all your Veins and Artery's because your nose is bleeding! Rather a bit of overkill!

 

At the very least....get a second opinion. Also....although this is a bit late to ask...did you get a CarFax report when you bought the car??? I'd check into its pedigree to see if there has ever been a flood or accident claim against this vehicle.
If there are dings in the history and you bought it from a new car dealership, you might be able to lodge a complaint against that dealership (which almost certainly has a CarFax account for the used vehicle side of their operation) for non-disclosure.
It won't go anywhere, but they might cut you a deal on the repair to get you off of their backsides, although if they're the same people that's giving you the wiring harness "diagnosis"....it might not be much of a "deal".........for YOU.
I would not replace the wiring harness! Wires do not just wear out, and neither do automotive connectors. They usually have to have a little help to "go bad."
In addition to a failing 12-V battery (which happened on my '10---they're notoriously weak) if could be something as simple as a loosened connector.

GOOD LUCK!

 

Wire DO wear out, or, at least, the insulation.

Most of all, here, are too young to remember fabric insulated wire.

That's what they used in the PzKwIII and PzKwIV tanks that Daimler Benz made for the Nazis and were fielded at Stalingrad.

Rats really liked to chew on the tarred fabric insulation.

 

Yes I get where your coming from, but this is a 2008 and even vermin damage can be repaired without replacing the whole harness, that I doubt has that much of a problem. It could be something as simple as a ground wire, but we need to know about the state of the 12v and if there are any codes.

 

As was mentioned in another thread about this same situation, that kind of unreasonable expense is just their way of saying that they don't want your business, because they can't make money on the fix any other way.

Rats do chew on present day wires, as a result of the use of peanut oil used in the plastic insulation. Codes might be able to tell where that damage might be, if it exists. I have fixed a rather bad case of that in the past, and it is a case of finding the spot, getting access, and very carefully splicing in some wire. Definitely less than $5.6k.

But the fact that it acted up while driving makes me think that is not what happened. If there was rodent damage, it would have thrown errors at start up.

 

Having 50 years of experience with electrical systems, I'll tell you that these "phantom" low amp draw drains or shorts are the toughest cases to troubleshoot, but it can be done. It takes a lot of experince and a lot of time to find them.

The current training of technicians use the "remove and replace" technique.

A really experienced master technician can find and fix the problem.

It can be a corroded connection or a wire with frayed insulation.

There are not many of us out there, who have the patience and experience to find it.

Definitely, I WOULD NOT replace the entire harness.

A "phantom" slow low amp drain can be detected with an ammeter attached to each circuit through a fuse socket adapter.

 

The other posters offer sound advice. Whenever something weird happens check the 12v voltage. If it is low fix that cheap problem first & most of the time you'll find the expensive problem disappears.

If the 12v battery is the problem I believe a "no start" situation or erratic traction battery charge/discharge cycles would be the symptoms. After the 12v boots the computers it isn't needed to run the car. There are reports here about cars run without batteries.