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This is just straight untrue. You can throw parts at the car while taking educated guesses, but to cost and time effectively fix the car you absolutely need the

by mox1 6y ago

This is just straight untrue. You can throw parts at the car while taking educated guesses, but to cost and time effectively fix the car you absolutely need the diagnostic software. Crank position sensors, cam position sensors, EGR, Fuel system pressure, per-cylinder electrical failures, etc, etc., etc.. can all be guessed at by a shade-tree mechanic. But good luck fixing it quickly and without buying a bunch of parts. My 2010 Mercedes van require parts to be electronically "mated" to eachother, so even if I know the right part, I need the Mercedes software to tell the computer to hook up with the new part. I've been a "shade-tree" mechanic for most of my life. I would say '98 is roughly correct when full fuel injection became pretty standard. Once you have that, you need a half dozen or so other sensors to make the system work. And you need precise fuel pressure. It just gets more complicated from there.

lmilcin 6y ago
You wrote it yourself: > "but to cost and time effectively fix the car you absolutely need the diagnostic software." > "etc, etc., etc.. can all be guessed at by a shade-tree mechanic. But good luck fixing it quickly and without buying a bunch of parts." That was exactly my point. Car CAN be fixed without the software. It just takes more time (and knowledge). If you are an owner of a repair shop then that is probably deal breaker. You can't hire actual engineers to fix cars, the cost would be prohibitive. But nothing is stopping you to fix the car (except if manufacturer like John Deere makes it their mission to stop you from repairing it). If electronics is broken your mission is to find the broken part and replace it, not reprogram it, which is basically the same as with mechanical faults.
smolder 6y ago
I too am a shade-tree mechanic. It's worth noting that early electronic fuel injection didn't require any external software or device. Rather, you would use a model-specific technique to put the vehicles computer into diagnostic mode, and it would blink codes at you from the check engine light, or perhaps show the code on an LCD that was normally for another purpose. This was late 80s and early 90s stuff using OBD1, the earlier diagnostic standard. On my Toyotas, I would need to jumper a couple pins in a connector under the hood with a paper clip, labeled T1 and E1, I recall. On my BMW, I had to turn the key to ON and then stomp the gas pedal 5 times in a few seconds. After counting the blinks, the meaning of the codes could be found in manuals. IMHO this was a great system and every bit as useful as what you get with basic OBD2 scanners, just without the scanner investment. I needed no tools to be told my catalytic converter or primary o2 sensor failed, etc.
throwaway0a5e 6y ago
All these things have known resistances and waveforms. They can all be diagnosed with a $5 multimeter and $50 scope. Fuel injection became standard closer to 88. It's not complicated. The systems are pretty tolerant and only need a few sensor to operate (albeit not perfectly). The precision required from various sensors and things is far less than what internet commenters will lead you to believe. Though if someone is gonna build something finicky of course it will be the Germans (requiring software resets when changing basic things is but one example).

by mox1 6y ago

lmilcin 6y ago

You wrote it yourself: > "but to cost and time effectively fix the car you absolutely need the diagnostic software." > "etc, etc., etc.. can all be guessed at by a shade-tree mechanic. But good luck fixing it quickly and without buying a bunch of parts." That was exactly my point. Car CAN be fixed without the software. It just takes more time (and knowledge). If you are an owner of a repair shop then that is probably deal breaker. You can't hire actual engineers to fix cars, the cost would be prohibitive. But nothing is stopping you to fix the car (except if manufacturer like John Deere makes it their mission to stop you from repairing it). If electronics is broken your mission is to find the broken part and replace it, not reprogram it, which is basically the same as with mechanical faults.

smolder 6y ago

I too am a shade-tree mechanic. It's worth noting that early electronic fuel injection didn't require any external software or device. Rather, you would use a model-specific technique to put the vehicles computer into diagnostic mode, and it would blink codes at you from the check engine light, or perhaps show the code on an LCD that was normally for another purpose. This was late 80s and early 90s stuff using OBD1, the earlier diagnostic standard. On my Toyotas, I would need to jumper a couple pins in a connector under the hood with a paper clip, labeled T1 and E1, I recall. On my BMW, I had to turn the key to ON and then stomp the gas pedal 5 times in a few seconds. After counting the blinks, the meaning of the codes could be found in manuals. IMHO this was a great system and every bit as useful as what you get with basic OBD2 scanners, just without the scanner investment. I needed no tools to be told my catalytic converter or primary o2 sensor failed, etc.

throwaway0a5e 6y ago

All these things have known resistances and waveforms. They can all be diagnosed with a $5 multimeter and $50 scope. Fuel injection became standard closer to 88. It's not complicated. The systems are pretty tolerant and only need a few sensor to operate (albeit not perfectly). The precision required from various sensors and things is far less than what internet commenters will lead you to believe. Though if someone is gonna build something finicky of course it will be the Germans (requiring software resets when changing basic things is but one example).