Repair - Valeo 530 29 912 Wiper Motor
Dec 27, 2019
A while ago, the rear window wiper of my car suddenly stopped working. There was no warning sign, no strange noises, no apparent reason why it stopped working.
The easy thing to do in a situation like this would be to replace the wiper motor completely. So, let's not do that and instead try to repair the control electronics of the motor.
Warning! Common sense required.
This is not a complete repair guide but merely a description of my experience. I am not responsible if you break something or hurt yourself or others in the process of attempting this repair.
Everything you do is at your own risk!
The great benefit of only repairing the control electronics is that removing the motor from the car is unnecessary. This saves a lot of time and effort, especially if the wiper arm is rusty and does not come off the motor shaft. Unfortunately, I did not know this at the time.
The great benefit of me not knowing this is that I was able to take some detailed pictures of the motor assembly.
The below picture shows the exact hook position as well as how the hooks are looking. This should make it possible (not easy, though) to remove the electronics module from the motor assembly while the motor remains in the car.
To remove the electronics part from the motor, there are three hooks that have to be loosened.
Hooks number one and two need to be pressed down and outwards from the motor.
Hook number three needs to be pressed down and inwards to the motor.
When all the hooks are loosened, the control module can be removed, and you will end up with something like this:
Considering the modularity of this motor assembly and how easy it is to remove the electronic part, I think it is a shame that in case of a defect, usually, the whole assembly gets replaced instead of just the electronics. I would not expect that a car repair shop performs PCB-level repairs, but since it is easily replaceable without soldering, there's really no reason not to do this.
But back on topic:
Now with the electronics removed, I would suggest testing the motor before continuing.
To test the motor, connect 12VDC to the red marked pins in the picture below. The polarity does not matter since it only affects the turning direction, which, in this case, does not matter. To supply the 12V, I would recommend a current-limited lab power supply or some other 12V power supply. However, I would not recommend a car battery since, in the case of a short circuit, the output current can be quite high.
In my case, the motor is luckily turning and draws about 1A of current.
Now that we can rule out the motor or any mechanical defect, let's have a look at the electronics.
After a first look at the PCB inside the electronics module, I noticed a suspicious black mark on one of the ICs. This looks very promising.
But let's start by identifying what each of those chips actually does.
The probably broken chip in the top right is a VN5016AJ-E High Side Driver from ST. Datasheet
The in the top left is a HUF76407DK-F085-D Dual N-Channel MOSFET from ON Semiconductor. Datasheet
The last chip in the bottom half of the PCB has the marking SQD2C 5ZSD. Unfortunately, I could not find a datasheet or at least a functional description of this chip. Since this motor is controlled via, as I assume, LIN bus, it is probably some kind of microcontroller.
A replacement for the broken chip can be bought from mouser.com for approximately $2.80.
Of course, there is always the question of why this chip died in the first place, but for now, let's just replace it and hope for the best.
Replacing the IC
From the datasheet, we know that this chip has an exposed pad, soldered to the PCB on the bottom side. This means that the only viable option to replace this chip is to use hot air. I recommend removing the PCB from the plastic enclosure. After all, it is not my goal to melt the enclosure.
Soldering Tips
There is a lot of information and misinformation on how to solder on the internet. I summarized the in my opinion most essential points.
Propper ToolsUse a real soldering station or hot air station with temperature control. Especially for electronics. The cheap soldering iron will just make your life more difficult.
Usa a clean tip and appropriat size tip.
FluxUse additional flux while soldering. Especially for lead-free solder. There is no such thing as to much flux. Clean off excessive flux after you are done.
Only use no-clean flux for electronics. Other types of flux may corrode and therefore destroy the PCB.
PracticePractice on old electronics. Try to desolder and resolder some components and see if it is still working afterwards.
Leaded vs Lead Free SolderDespite what a lot of people tell you, there is no real disadvantage in using lead-free solder. You just need the right tools and some practice. However, leaded solder is more forgiving of bad tools or if you don't know what you are doing.
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To desolder the PCB, I use a tin suction pump for the majority of the solder and clean the rest up with desoldering braid.
To desolder the chip, I would recommend using a hot air soldering station. If you don't have a hot air soldering station, I would recommend buying one! Alternatively, a hot air gun probably works as well. Just be careful not to overheat the board. If you are not sure how to use hot air for soldering, please refer to one of the countless hot air soldering tutorials on the internet.
Luckily this is a small board with a small thermal mass, so removing the chip is quite easy.
Now all that is left to do is soldering the new chip onto the board.
After cleaning the board, white the old chip (top and bottom) next to it should look somewhat like this.
The Result
And it works again.
Mechanics
Since I already have the motor on my desk, let's have a look at the mechanical part as well.
