2008 car. Arrived with error B2036: “Open circuit of seat belt pretensioners”. This error is part of the Pre-Collision System, a collision avoidance system. Consists of a radar, information processing unit, executive devices. If the PCS system determines the probability of a collision, then it simultaneously sends a signal for braking and activates the seat belt pretensioning system, and in some versions it lifts and moves the head restraints to protect the head of the driver and passenger from external influences.
General view of the system in the figure below:
A block diagram showing the composition and location of elements of a PCS system:
How the radar works:
The appearance of the radar:
Who cares, you can watch a video on the topic – Pre-Collision System (PCS)
In our case, the PCS system will not work, as there is an error B2036 for triggering the seat belt pretensioner.
It is important not to confuse the “inertial seat belt system” and the PCS system – in the first case, the seat belts are blocked as a result of the inertia of the driver’s body, and in the second case the seat belts are pulled by a special motor on the command of the PCS system.
There are limitations in the system, it will not be able to work correctly in such situations:
· On roads with sharp and sharp (closed) corners and uneven surfaces
· If your car unexpectedly cuts another car, for example, when overtaking
· In adverse weather conditions, such as heavy rain, fog, snow
· If your car stalls and the VSC turns off
· When your car has a very strong tilt in one direction
· In case the radar direction axis is down
· In the case when the sensor is very dirty and cannot work to detect an obstacle, the PCS system will be automatically turned off and a warning icon will appear on the instrument panel.
I started the test with the main one: we need to understand what specifically does not work and what could be the reason; this is either connecting wires, connectors, fuses or the control unit itself. I check the signal flow:
And I determine that there is no constant “plus”. In the diagram below: there should be a plus, but it is not.
Now, in order to finally make sure of the cause of the malfunction, I submit “my plus” (green wire in the photo):
And on the dashboard the CHECK lamp and the PCS indicator go out.
I’m checking again (This is a prerequisite for all such work): I turn off the power – on the dashboard CHECK and the PCS system indicator light up. So, my assumptions are correct, it is necessary to look for a malfunction in this direction.
Dismantled the mounting block, found the necessary contacts, tracked where and what goes.
I saw a “burnout” and something else interesting:
In the photo above, the screwdriver is on the “track”. If we trace left and up, we will see that the narrow path goes into a fairly wide one. A “burnout” is just in the narrowest place.
The conclusion that “the Manufacturer is to blame, did not calculate the strength of the current – this caused the damage to the track” instantly begs..
The fuse is off, it is rated for sufficient current..
But after talking with the owner of the car, he thought about it, another version of what happened: a client never put on his seat belt, there are such drivers.
The belt dangled, and in order to prevent the light bulb irritating the eyes from flashing on the dashboard, he inserted the plugs into the place where the seat belt was to snap.
And what could be: during the operation of the PCS system, the motor starts to tighten the seat belt – it tightens to a certain limit and stops. And in this case, it turns out that “the motor pulls and pulls, pulls and pulls …”.
The current increases greatly and … because of this, the “track” on the board could burn out or not, as you think?
The restoration of the board was carried out by the “collective farm method”, but reliably. A detailed description of the entire repair process, features and additional comments can be seen on my working video:
Kudryavtsev Mikhail Evgenievich
© Legion Avtodata
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