I'm an Idiot
As I mentioned in my last post, Deb had a bit of trouble with a Camry a few weeks back.
And I, instead of doing the intelligent thing, which was to have it taken to a professional automobile repair shop where they are able to diagnose the issue within seconds and then have it repaired in a day or two (while charging me an arm and a leg for the privilege), decided that it would be fun to fix it myself; so I told the very nice tow-truck driver drop it off at my house.
Because I'm an idiot.
And because I thought it would be easy.
Ha!
Easy.
It should've been easy if I'd been dealing with a car that wasn't handicapped by overprotective software. Like, say, a 1968 Volkswagen Beetle.
But I wasn't.
The 2000 Toyota Camry was designed with the latest (at the time) safety gizmos and efficiency factors, all under the control of a software program running on a computer. This wonderful computer program does nifty things like making sure that the fuel pump doesn't turn on unless certain things are also happening, like the ignition switch is ON, the crankshaft is turning, the camshaft is turning, air is actually being pulled into the engine ... all sorts of crazy things.
Problem is, this old brain of mine is pre-2000 and operates on different principles.
For example, when I turn the ignition switch to ON (not START), I expect to hear the fuel pump power up for two seconds. It stops after two seconds because it's waiting for the operator to turn the switch to START. If the operator turns the switch to START, the fuel pump turns on because the cylinders start to burn some of that fuel so more is needed.
In the old Subaru days, I had a car whose fuel pump died. It was easy to tell because when I turned the switch ON, there was no fuel pump sound. It was easy to tell that the fuel pump was bad.
In the case of the Toyota, I thought a similar thing had occurred, so went through all the troubleshooting steps pertinent to a fuel pump problem. Oddly enough, I could not discern a problem.
Until I obtained the Haynes manual (which Cheryl sweetly ordered for me!) and discovered that this car had a few features of which I was unaware.
For example -- the little relay that controls the fuel pump operation is directly controlled by the little computer. And the little computer will not turn on the fuel pump unless (a) the ignition switch is ON [but only for 2 seconds]; (b) the ignition switch is START and the crankshaft is spinning and the camshaft is spinning and air is being pulled into the engine; (c) the ignition switch is ON and the crankshaft is spinning and the camshaft is spinning and air is being pulled into the engine.
There are important Safety reasons for these "rules".
And the programmers only do the things that the
-- But before we get into the reasons behind that conclusion, let's go over a little automotive theory, OK?
In the old days, automobiles had these really complicated mechanical contraptions called 'carburetors' which mixed the air and fuel into a kind of vapor which was then pulled into the cylinders via the vacuum caused by the downward movement of the piston.
This is, of course, dreadfully inefficient - so it was necessary to come up with something much, much better for the Age of MPG.
The Efficient ECU
Modern internal-combustion automobiles operate by directly injecting a precisely-measured amount of fuel into the cylinders, which maximizes both power and fuel efficiency (and has a long and colorful history).
Unfortunately, getting all that precision into the mix -- controlling the flow of air and fuel according to an extremely complicated formula which takes into account various readings of temperature, pressure, altitude and chemical compositions across the entire combustion cycle - requires either a horribly complex mechanical apparatus, of which several were designed way back in the 50's, or a computer.
You know all about computers, right? How much fun they are to work on, with the big fancy LED displays and the wireless keyboards & mice and the ridiculously huge multi-terabyte drives and the wireless internet and the always-dependable, never-in-the-middle-of-updating Windoze 10 installed?
Now imagine working on one with no display, no keyboard, no mouse, with only a teeny-weeny bit of memory, no wifi, and some proprietary software you can't even look at, connected to every little switch & sensor on your car for the express purpose of maximizing every drop of fuel that goes out of that tank into that engine.
(And ensuring that the car meets all those federal safety and emissions requirements, too!)
This fancy little embedded system / computer is called the ECU (Engine Control Unit).
And it adds just enough complexity to the system to completely befuddle an idiot like me.
Relays & Switches
The ECU is effectively a automated switching system which determines (1) how much air to mix with a specific amount of fuel to result in a specific amount of motive force; (2) which specific moment to provide the spark in order to ignite the aforementioned combustibles; and (3) how well the combustion actually occurred so as to modulate the amounts of fuel and air to obtain the optimum combustion on the next cycle.
All these things are written into the program which the ECU is running.
In order to accomplish these things, the ECU has control over several critical functions, including (a) the fuel pump; (b) the spark generator; (c) the intake and exhaust air flow. The ECU utilizes electromechanical relays to perform some of these jobs, where a small signal from the ECU activates a large motor or solenoid to perform some desired function.
And I, instead of doing the intelligent thing, which was to have it taken to a professional automobile repair shop where they are able to diagnose the issue within seconds and then have it repaired in a day or two (while charging me an arm and a leg for the privilege), decided that it would be fun to fix it myself; so I told the very nice tow-truck driver drop it off at my house.
Because I'm an idiot.
And because I thought it would be easy.
Ha!
Easy.
It should've been easy if I'd been dealing with a car that wasn't handicapped by overprotective software. Like, say, a 1968 Volkswagen Beetle.
But I wasn't.
The 2000 Toyota Camry was designed with the latest (at the time) safety gizmos and efficiency factors, all under the control of a software program running on a computer. This wonderful computer program does nifty things like making sure that the fuel pump doesn't turn on unless certain things are also happening, like the ignition switch is ON, the crankshaft is turning, the camshaft is turning, air is actually being pulled into the engine ... all sorts of crazy things.
Problem is, this old brain of mine is pre-2000 and operates on different principles.
For example, when I turn the ignition switch to ON (not START), I expect to hear the fuel pump power up for two seconds. It stops after two seconds because it's waiting for the operator to turn the switch to START. If the operator turns the switch to START, the fuel pump turns on because the cylinders start to burn some of that fuel so more is needed.
In the old Subaru days, I had a car whose fuel pump died. It was easy to tell because when I turned the switch ON, there was no fuel pump sound. It was easy to tell that the fuel pump was bad.
In the case of the Toyota, I thought a similar thing had occurred, so went through all the troubleshooting steps pertinent to a fuel pump problem. Oddly enough, I could not discern a problem.
Until I obtained the Haynes manual (which Cheryl sweetly ordered for me!) and discovered that this car had a few features of which I was unaware.
For example -- the little relay that controls the fuel pump operation is directly controlled by the little computer. And the little computer will not turn on the fuel pump unless (a) the ignition switch is ON [but only for 2 seconds]; (b) the ignition switch is START and the crankshaft is spinning and the camshaft is spinning and air is being pulled into the engine; (c) the ignition switch is ON and the crankshaft is spinning and the camshaft is spinning and air is being pulled into the engine.
There are important Safety reasons for these "rules".
And the programmers only do the things that the
-- But before we get into the reasons behind that conclusion, let's go over a little automotive theory, OK?
In the old days, automobiles had these really complicated mechanical contraptions called 'carburetors' which mixed the air and fuel into a kind of vapor which was then pulled into the cylinders via the vacuum caused by the downward movement of the piston.
This is, of course, dreadfully inefficient - so it was necessary to come up with something much, much better for the Age of MPG.
The Efficient ECU
Modern internal-combustion automobiles operate by directly injecting a precisely-measured amount of fuel into the cylinders, which maximizes both power and fuel efficiency (and has a long and colorful history).
Unfortunately, getting all that precision into the mix -- controlling the flow of air and fuel according to an extremely complicated formula which takes into account various readings of temperature, pressure, altitude and chemical compositions across the entire combustion cycle - requires either a horribly complex mechanical apparatus, of which several were designed way back in the 50's, or a computer.
You know all about computers, right? How much fun they are to work on, with the big fancy LED displays and the wireless keyboards & mice and the ridiculously huge multi-terabyte drives and the wireless internet and the always-dependable, never-in-the-middle-of-updating Windoze 10 installed?
Now imagine working on one with no display, no keyboard, no mouse, with only a teeny-weeny bit of memory, no wifi, and some proprietary software you can't even look at, connected to every little switch & sensor on your car for the express purpose of maximizing every drop of fuel that goes out of that tank into that engine.
(And ensuring that the car meets all those federal safety and emissions requirements, too!)
This fancy little embedded system / computer is called the ECU (Engine Control Unit).
And it adds just enough complexity to the system to completely befuddle an idiot like me.
Relays & Switches
The ECU is effectively a automated switching system which determines (1) how much air to mix with a specific amount of fuel to result in a specific amount of motive force; (2) which specific moment to provide the spark in order to ignite the aforementioned combustibles; and (3) how well the combustion actually occurred so as to modulate the amounts of fuel and air to obtain the optimum combustion on the next cycle.
All these things are written into the program which the ECU is running.
In order to accomplish these things, the ECU has control over several critical functions, including (a) the fuel pump; (b) the spark generator; (c) the intake and exhaust air flow. The ECU utilizes electromechanical relays to perform some of these jobs, where a small signal from the ECU activates a large motor or solenoid to perform some desired function.
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