This is a story about how, when diagnosing a malfunction on a 2006 Mitsubishi Lancer 9 vehicle, decided not to use “heavy artillery” in the form of an oscilloscope, but completely different devices that he invented on his own. And I can say that the very notion, which will be discussed below, helped me for the first time, it helps me now.
It happens: “A series of identical malfunctions has gone.” Literally in a row, Lancers with idle problems began to arrive for repairs. And this car also suffered from this: “The RPM of the XX either fell, then soared up”.
On this type of idle speed controller, the operating principle is as follows (for convenience, I used the MOTORDATA program: http://motordata.ru/ru – whoever used it knows that “there is always not enough time during repair”, but for a quick search the program Motordata presents very operational capabilities):
4 negative potentials are fed to the stepper motor (circuit above, circled) by the control unit in a certain sequence, the rod moves by the required number of steps and thereby the required idle speed is reached.
And here is the device itself, which was invented and manufactured independently:
I repeat once again that this is not a replacement for the oscilloscope and other diagnostic devices, it is just an attempt to reduce the time for certain diagnostic work. Of course, given the quality of the measurements.
My device is a four-channel LED indicator. I can hang 4 different potentials on it and see what is there, “plus or minus” and whether they exist at all. The LED lights up red or green, or does not light at all. The device can be called a “logical probe”.
In my situation, I connect this probe to 4 channels and immediately see where and what potential.
With the engine running, at different speeds, only two red and two green LEDs should alternately light up. The simultaneous illumination of three or four LEDs of the same color is a sign of a malfunction of the idle speed regulator, or its power circuits, or control. The brightness of the LEDs (two red or green) must be visually the same, otherwise there may be a malfunction.
Consider the operation of this indicator probe at idle with periodic podgazovki.
1. Alternating switching of two red and two green LEDs:
Normal system operation
2. Lights up red without switching to green:
A control transistor or a given electrical circuit in an open circuit, or a short to (+).
3. Green on without switching to red:
Missing (+) power supply, winding in open or short circuit control circuit on (-).
If we have two malfunctions on one section of the electrical circuit, for example, an open winding and an open circuit of the control transistor, then the diagnostic LED responsible for the indication of this channel will not light up in any color.
Thus, I can expressly determine the serviceability or malfunction of the idle speed controller:
· The transistor is broken or not, it opens or not
Is the wire broken?
As a result, I found out that the cause of the malfunction (the engine speed jumps up or down) is on the control unit board – a malfunction of the transistor of the idle motor control driver.
With this malfunction, everything is clear: “Repair, or change the driver or control unit.” But I want to add a few words about the malfunctions, which “it is not clear where they come from and there are no blame – except for the Manufacturer”.
So always think when “out of the blue there is a malfunction”.
Didn’t you do anything with the machine? They did nothing. And the malfunction once – and formed. Means: “Shame on the Manufacturer!”. So, “the Mitsubishi company sucks!”.
But in fact, a lot of malfunctions on client machines have the status of “introduced”. How and by whom? And look at the photo:
Please note how the measuring device (mine, in this case) is connected to the electrical circuits. I’m not breaking anything, the insulation of the wires and the core itself remain intact.
However, how many times had to repair cars in which a malfunction arose due to improper connection!
An “incorrect” connection is when an electrician roughly pokes a needle or probe into the braid of a wire, thereby damaging the insulation. It seems to be a trifle? But this is a “delayed malfunction”: time passes, moisture and dirt get into the punctured hole, and now the slow corrosion process begins, which eventually leads to the appearance of a “non-contact effect”. That is, the wire in this place loses contact. He or “greens” will cover in this place, or inside he will break when touched. And worst of all – if it breaks, but not completely, and there is a malfunction “floating” in the car: that is, there is no contact. And look for such a malfunction-fistula … and get angry with the manufacturer or anyone else … But outside, everything can be clean and inconspicuous.
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