According to the all-wheel drive system of cars, there are many copyright articles on the portal of the Legion-Avtodata company (list at the end of the article). About four-wheel drive Mitsubishi cars are well described in the article “Four-wheel drive Mitsubishi” .
The car, which came for repair, also had four-wheel drive with the name “Part Time”.
What it is:
“This is one of the simplest types of 4WD (on some models it is called EasySelect) – with a connected front axle, no center differential – it is used on the original rear-wheel drive models.
The scheme provides for direct control of the transfer case using a lever. Initially, the front drive shafts were connected to the wheels with mechanical freewheels (“hubs”) with manual or automatic drive. On more recent models, to facilitate the process of connecting the front axle, the ADD system is used, which, using a pneumatic actuator, disconnects one of the front axle shafts.
Pros – relative simplicity of design, the presence of a downshift.
Cons – “4WD” mode can only be used on slippery surfaces (ice, snow, wet road) and for a limited time – otherwise noise, fuel consumption will increase, controllability worsens, tires and transmission elements wear out a lot. “Manual” hubs are reliable, but not too convenient to use, and automatic survivability is far from ideal “. (a source)
In this article, I would like to raise issues that will be useful both to the owners of such cars, and to those who repair them:
· Some reasons for the failure of four-wheel drive
· How to correctly check purchased parts for four-wheel drive
· Features of summer operation of a car with all-wheel drive
And since we will come across the concept of “actuator” along the way, I’ll say what it is in my opinion: “Actuator (or“ actuator ”, English word * actuator * ) is an actuator that converts one form of energy into another. For example, hand drill, jack.
Well, before us is a Mitsubishi Pajero Sport car, customer complaints: – Four-wheel drive does not work for me.
First of all, I open the hood of the car.
Why am I doing this? Based on the state of the components and assemblies of the engine compartment, you can draw your own conclusion about how carefully the car owner treats his car. It takes a little time, and the scope for thoughts is great.
Next, the car rises on a lift. We look, we check. Diagnostics showed that the “native” (standing on the car) valve ( Solenoid valve A and Solenoid valve B ) do not work: “not blown”. There was no point in repairing, and he told the client that the valve should be changed. The car owner has left to acquire new valves. And while he is driving, let’s see the device of this system.
The following is a schematic diagram of a front-wheel drive control system:
Solenoid valve (Solenoid valve A and Solenoid valve B), which I already mentioned, in the figure under number 15. So they did not work.
Valves are checked simply, the figure below shows how the first and second valves are checked.
As written in the figure, “valve resistance should be between 36-46 ohms.” Which is also easy to verify..
Now summarize: “ For what reasons the all-wheel drive system may not work “.
1. Problems in the electrical part (for example, open circuit or short circuit of the electric wire (power key), as a result of which power is not supplied to the valve)
2. Mechanical valve malfunction (clogging)
3. The vacuum tubes are mixed up (pay attention to the figure below, where the color identification is indicated):
4. The direction of air flow is reversed (indicated by arrow):
5. Malfunction of vacuum tubes (mechanical damage, clogging, etc.)
6. Faulty actuator (key 16 in the figure above)
These are major malfunctions. Now we reveal a private malfunction on this car: the client returned and brought the valve from the disassembly. He was in a hurry, so he wanted me to put them on the car right away. But in our business haste is not an assistant, so I said that they must first be checked. What he did:
Well, as you already understood from the video: “you can’t trust, you must check!” One valve at once “on the go”, in the trash, when checking the resistance, he showed his inoperability (up to 1.3 megohms):
The second valve: although its resistance is even less (40 kOhm) than that of the previous one (1.3 MΩ), it still does NOT fit into the parameters (36–46 Ohm)!
Conclusion: “Give the valve back and look for workable parameters”.
The second part of my story will be devoted directly to the actuator himself, because another car came with the same problem: “Four-wheel drive does not work – it does not turn on”.
We look, check: while it is not clear – when the four-wheel drive is turned on, the indicator blinks, and the half-shaft does not turn on.
I delve into the problem:
· Check valves – work
· I check the correct installation of vacuum tubes – everything is correct
Since the main thing is checked and does not cause suspicion, then we must proceed to the inspection of the actuator itself. Its device is the simplest:
And here is the general connection diagram of the actuator to the vacuum lines (and to understand a small photo of our actuator on this car):
If the photo is poorly visible, I can tell you: “The upper part of the actuator is molten (it was subjected to thermal heating), as a result of which the vacuum supply fitting to the outer chamber (where the tube with the blue strip is connected) is damaged, even destroyed and the full control of the actuator is impaired”.
In simple words: “The top of the actuator has melted”.
Alternatively, the reason for this could be a trip on burning grass, so the advice to the owners: “Try to avoid traveling on burning grass or stubble in the warm season, do not leave the car in thick grass, which can catch fire when you move away from the car to collect mushrooms or fishing “.
Below is an application where you will find the addresses of articles on the Internet portal of the Legion-Avtodata company on the topic “Four-wheel drive.” Come in handy.
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