Complete car rewiring with module delete possible?

Post by **gnalan** » 30 Nov 2020, 22:32

Just curious if anyone has tried this, or had any luck rewiring their car, by either deleting most of the control modules with bypassed wiring harnesses or doing a complete bumper to bumper rewiring job.

Something I've been thinking about, since I'm more used to older cars that have less parts to worry about. Obviously some things would need to be retained, like the complete SRS system, door modules, ABS, and both the ECU and TCM (although both of those could be replaced with an aftermarket system).

I don't know anything about the CAN BUS system, how it even works, or why the appeal of having such a system exists. Cars used to be simple to work on, and didn't need miles and miles of wiring, the complexity of having so many on board control modules, or dedicated software and hardware to interface with the car to get everything to work together. It seems to me that the car companies only did this to "try" and make the backyard mechanic obsolete, and make you bring your car back to the dealer for overpriced parts and labor.

I'm more curious than anything, however if a lot of unnecessary parts can be removed it may be something I look into in the future.

Post by **abscate** » 01 Dec 2020, 02:30

Cars aren’t simple to work on for the novice, look at some of the threads here on people starting out. Some don’t even know their oil had to be changed.

Having stuff controlled by modules and comm lines requires learning some new stuff, but it’s 100x more reliable than analog stuff, and easier to troubleshoot with a scan tool.

In 2012 , the Canadians invaded us, leaving ‘EHS, in our speech patterns, converting Dunkin to Tim Hortons, and leaving maple leaves everywhere. We identified them by their politeness, and packed them up into detention centers, then sent them home on the Can Bus.

IslandV70 · Post by **IslandV70** » 01 Dec 2020, 07:44

Yes this could be done. It would take a huge amount of time, cost a huge amount of money, and require expertise in both the new system and the old system to a level possessed by almost no one.
It would probably be easier to just build a car from scratch that did what you wanted it to do.
* the airplane equivalent would be ripping out all the fly-by-wire stuff and replacing it with hydraulics and stainless-steel cables. It would be a decade-long project and no one would want to fly in it after you were done.

Post by **volvolugnut** » 01 Dec 2020, 08:56

A basic introduction to Canbus technology is https://www.csselectronics.com/screen/p ... anguage/en.

volvolugnut

Post by **gnalan** » 02 Dec 2020, 18:51

It was just a thought. Maybe if I can learn the canbus system it won't be too bad.

I just don't like how they're making cars smarter than their drivers. Do kids these days even know how to parallel park without pushing a button to do it for them, or using backup cameras instead of their mirrors or actually turning their neck to look behind them?

Plus cars that hit the brakes for you, or keep you in your own lane, aren't keeping anyone safe in my opinion. They're just letting the driver do whatever they want except actually paying attention to the road.

That's the end of my rant. Thanks for the info, I'll do some reading up on how exactly the canbus system works. The little bit I have read makes it sound like a good thing, but I need to learn more about it still.

Post by **volvolugnut** » 02 Dec 2020, 19:28

Electronics have made vehicles more powerful (variable cam timing as an example), cleaner (continuous fuel ratio adjustments), more efficient (again continuous fuel adjustments), and much safer (antilock brakes, air bags, and stability control). They have also made vehicles more expensive, harder to service with simple tools, and more complex.
I think it is worth the trade offs.
volvolugnut

Post by **abscate** » 03 Dec 2020, 04:56

I do worry about the anthro part of safety engineering. They do worry about this in flight, where it has gotten so safe that pilots literally do fall asleep in flight.

There is no substitute for high situational awareness while driving.

Post by **vtl** » 03 Dec 2020, 07:46

CAN-bus is awesome and is a major improvement over inches thick wiring harnesses. Usually when you have a failure, it is a failure in the remaining analog parts - it is the analog sensor or its wiring. However, digital counterpart is usually able to diagnose it and raise a red flag, which you can read, along with environmental and driving conditions for the moment when the error has happened. Diagnosis becomes easier for us, tree shade mechanics.

What is really bad for longevity in new cars is a low-grade eco-plastic everywhere, even in engine, that starts to decay even before the car hits the dealer's lot. Plastic and designed-to-fail parts to force your buying a new car after the warranty expires.

Post by **gnalan** » 03 Dec 2020, 08:05

vtl wrote: ↑03 Dec 2020, 07:46 CAN-bus is awesome and is a major improvement over inches thick wiring harnesses. Usually when you have a failure, it is a failure in the remaining analog parts - it is the analog sensor or its wiring. However, digital counterpart is usually able to diagnose it and raise a red flag, which you can read, along with environmental and driving conditions for the moment when the error has happened. Diagnosis becomes easier for us, tree shade mechanics.

This makes a lot of sense. I guess I didn't really look at CAN-bus as being a good thing, but from what I've read about it, plus what you just said, I'm beginning to come around to liking it. 4 wires between the different modules for communication is a lot better than everything needed to be cross wired to tie them together. I'm sure there's other benefits I haven't read about yet, and haven't learned yet, but I'm learning.

What is really bad for longevity in new cars is a low-grade eco-plastic everywhere, even in engine, that starts to decay even before the car hits the dealer's lot. Plastic and designed-to-fail parts to force your buying a new car after the warranty expires.

Like the horrible glue they used on the interior door panels? I still haven't found an adhesive that'll hold them together right yet. I don't know if the green stuff needs to be scraped off first, or if I need a stronger adhesive.

I've already replaced my fuel injector connectors with new ones, since the original holding tabs were broken on 3 of them and the other 2 broke just trying to remove them, when I did my PCV system replacement. Plus most of the wiring loom is disintegrated under the hood, especially for the injectors and coils. Too much heat, cheap plastic, plus them being covered with even more plastic to "protect" (read bake the wiring by trapping the excess heat in) everything.

Post by **vtl** » 03 Dec 2020, 08:23

gnalan wrote: ↑03 Dec 2020, 08:05 This makes a lot of sense. I guess I didn't really look at CAN-bus as being a good thing, but from what I've read about it, plus what you just said, I'm beginning to come around to liking it. 4 wires between the different modules for communication is a lot better than everything needed to be cross wired to tie them together. I'm sure there's other benefits I haven't read about yet, and haven't learned yet, but I'm learning.

It is just 2 wires: CAN uses a differential signalling, its end points share the same signal media in time. Just 2 wires for all the modules sitting on that CAN-bus (P2 platform has 2 CAN-buses).