Why Do Vehicles "Wear Out"

[Kurtatron]

My 1991 Previa is still running fine at 200k miles. I’m shocked by the amount of electronics on it. It has an ECU and a dozen of so electronic modules underneath the dashboard. Despite all those electronics, everything’s still working.

 

[y_p_w]

Of course SMT chip caps are notorious for failure modes due to board warping, but that's a different problem... I'm amazed that more circuit boards don't fail due to barrel cracking from heat cycling, or other woes from age. IC's have gotten to be pretty good at being long life but even they too can random decide to die (but I suspect secondary effects are more to blame, like not sealed up quite as good as one thinks).

The biggest issue with ICs is electromigration of metal traces. It happens when electrons passing through carry away/redistribute metal atoms. I remember it was a big issue when aluminum traces were prevalent, and I thought that alloying with a bit of copper helped.

 

[gfh77665]

It’s been my experience that “usually” it’s a transmission related failure. The average driver will take their car to a quick lube where at least the engine oil is changed and basic fluid checks are done. I’d be willing to bet that most of the vehicles on the road are overdue for trans maintenance especially with the lifetime fill push from the manufacturers. Many people won’t spend the $2-4k to R&R a transmission on a vehicle with 150k+ miles. Many people don’t even have that kind of funds put back.

I agree, the trans is culprit #1.

 

[supton]

The biggest issue with ICs is electromigration of metal traces. It happens when electrons passing through carry away/redistribute metal atoms. I remember it was a big issue when aluminum traces were prevalent, and I thought that alloying with a bit of copper helped.

Interesting. Now that you say that, I recall hearing about electromigration a few years ago... I think with regards to low voltage chips with fine geometries.

I'm not sure what wearout is for EEPROM structures but that could be in the mix too. Once programmed I don't think they wear... but I know the parts we make, at least some of them, have EEPROM's. Not quite OTP but not meant for 1,000's of write cycles either.

 

[KrisZ]

My 1991 Previa is still running fine at 200k miles. I’m shocked by the amount of electronics on it. It has an ECU and a dozen of so electronic modules underneath the dashboard. Despite all those electronics, everything’s still working.

Electronics in vehicles is nothing new. The difference though is that the old ECUs didn’t communicate between each other and were not on a network. These were stand alone devices. Today almost all the electronics are on a network and must be programmed in, in order for the network to recognize them. The electrical signal they send and receive must also be different, not just steady 12V, or 5V, but a square sign wave. So simple electrical signal diagnosis becomes more complicated.

 

[zzyzzx]

Will they? You can’t pull a gauge cluster out of a wrecked modern car and put it in your car without the dealer reprogramming it. Electronic parts are specific to the car they were installed in.

Even down to the passenger seat in an F150.

That's why I have Forscan.

 

[zzyzzx]

Seems wrong--won't be long before TPMS sensors are VIN coded too. Sheesh.

TPMS sensors already require programming.

 

[supton]

TPMS sensors already require programming.

I thought that was to match the number already stored in the (whatever the TPMS receiver is called). I guess if you buy blank TMPS sensors, they would need a number, any number, entered in: but I thought they were coming blank so as to make it easier for shops to swap in.

And that's the point, the programmer is getting cheap, and now "anyone's" sensor can be swapped in. I guess if the programming tool for telling the Ford seat what it's going into is cheap and easily available, then I'm tilting at windmills.

 

[Patman]

TPMS sensors already require programming.

Not always. With my C7 Corvette you can buy a new sensor and just replace the old one and drive for a few miles and it automatically calibrates itself. With the C5 and C6 they said it needed to be programmed by the dealer but the DIY method was to just hold a strong magnet near the newly installed sensor and it would start working (I tried this and it did work)

 

[y_p_w]

Interesting. Now that you say that, I recall hearing about electromigration a few years ago... I think with regards to low voltage chips with fine geometries.

I'm not sure what wearout is for EEPROM structures but that could be in the mix too. Once programmed I don't think they wear... but I know the parts we make, at least some of them, have EEPROM's. Not quite OTP but not meant for 1,000's of write cycles either.

I remember the discussion of it in several classes when state of the art was 1 micron, so it's an issue that's been around for a while. I recall one solution was to widen the metal traces. I don't recall that it affected delay much, as it's primarily an RC delay. The capacitance will go up proportionally as the resistance going down.

There were OTP EPROM. For a class with a board level project, we had one student who had previously worked at Cypress Semiconductor and managed to get 10 EPROMs for each project team. They were essentially the same as windowed EPROMs, but without the expensive glass window. I've heard of some people managing to break off the packaging and erasing them, but something tells me that wasn't recommended.

I think in the long run EEPROMs might wear out. They work with a floating gate, and that gate will leak charge over time and possibly as there's voltage applied to the gate. Obviously the leakage is fastest during an erase cycle. Flash memory definitely wears out or the devices fail. I just had a SATA SSD fail, and I'm fortunate that the backup mostly worked. I didn't even detect it until I tried to restore an iPad from a backup and found that it wouldn't complete. Then my computer started showing signs of drive failure.

 

[PandaBear]

For me, wear out involves gasket leaks over time due to aging, deposits of combustion byproducts, friction parts (transmission clutch packs and bands, brake pads) wearing, chemical breakdown of battery and fluids (esp the lifetime), paint wearing out, metal rusting despite it doesn't impact me, and most importantly:

Owner getting bored of it due to fashion.