# How a cheap component could help kill off combustion cars



## Curt Renz (May 22, 2017)

Reuters - May 30: How a cheap component could help kill off combustion cars


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## FRC (Aug 4, 2018)

I'm not sure I understand how the wiring harness shortage is specific to ICE vehicles. EVs require harnesses also; in fact, many (most?) of us are currently awaiting a replacement of the rear harness under recall.


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## SalisburySam (Jun 6, 2018)

FRC said:


> I'm not sure I understand how the wiring harness shortage is specific to ICE vehicles. EVs require harnesses also; in fact, many (most?) of us are currently awaiting a replacement of the rear harness under recall.


If I read the article correctly, their point was hand-made harnesses in ICE vehicles vs. digitally-made harnesses in newer vehicles that are predominantly EVs. And you're right…then there's that pesky rear harness issue about which I'm hearing crickets from Tesla.


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## JasonF (Oct 26, 2018)

FRC said:


> I'm not sure I understand how the wiring harness shortage is specific to ICE vehicles. EVs require harnesses also; in fact, many (most?) of us are currently awaiting a replacement of the rear harness under recall.


Wiring harnesses are not specific to ICE vehicles. The article didn't do enough research - the issue is _direct_ wiring harnesses, which is an issue that plagues _legacy_ vehicles, but not all ICE vehicles. Direct wiring harnesses mean anything controllable in the car has specific wires going to it just for that purpose. Tesla uses CANbus, and a lot of other vehicles do as well. That's a serial communications protocol, which means you can chain together all controllable components without giving each one a separate control wire.

That doesn't get rid of wiring harnesses, it just makes them simpler, use fewer miles of wire, and a lot less labor to produce. It used to be the cost difference between legacy wiring harnesses and CANbus based ones wasn't much, but only because the legacy ones were made by hand in low labor cost countries - but with that falling apart now, legacy wiring costs a _lot_ more.

Since most automakers don't do iterative design changes, changing the wiring harness to CAN style means redesigning the entire car. And right now, it makes sense to spend redesign money on EV's, and not ICE vehicles. So that's _really_ how the humble wiring harness is hastening the move to EV's.

Case in point of how legacy wiring causes issues as automakers hesitate to do a full redesign: A lot of cars that haven't gone all to CANbus detect brake pedal presses by looping through the rear brake light harness. They would have two loops: One through the brake light harness for the ABS system, and one for cruise control. The end result to this ridiculous hack is when one of the rear brake lights burn out or short, cruise control quits working, and you get an ABS failure light. Since both talk to the main engine computer, it sees two faults, switches on the Service Engine light, and puts the car into limp-home mode. All over a burned out light bulb.


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