i have a w208 merc the soft top will not go down or up and the windows do not go up or down . its been on a diagnostic machine and it comes up with a error soft top control module unit 52 where will i get one not to expensivve or second hand i live in the uk regards steve

 

Hi Steve,
Are you located near the salt water or air? The corrosion has a party on these systems when climate tears them down. I read about a W208 waterside having this problem.

It is easy for a technician to connect a STAR tool or an OBD2 reader but do they care or know how to test the circuits for a fault.
I bet it is a blown fuse or broken wire from one of the sams. (Signal Acquisition Module).
Good luck and by all means get a second opinion mate.
Cheers

 

The shop that diagnosed your problem found a B1000 DTC (diagnostic trouble code), which indicates a possible fault with your N52 controller.

This does not necessarily mean that the controller is faulty and needs to be replaced. There have many instances where replacement controllers were installed and the problem persisted.

The first thing a qualified tech would do when this code is detected, would be to check for voltage at various pins on the N52 connector. Doing this would determine if the problem is that the controller is not either receiving the necessary power supply to operate or internally passing power to other sub system (e.g. such as the motors that operate the rear windows etc.).

As GatorMB suggested, additional trouble shooting often finds that the cause and remedy is simply that the controller is not getting the necessary power supply to operate.

Power to the N52 controller is fused in 3 different circuits. Specifically, in fuse block F4, located inside the trunk behind the battery, there are 2 fused circuits. The circuit to power the controller is provided through a 15A fuse at position #11 and at position #13, there is a 40A fuse, dedicated to power and protect only the pump motor. Additionally, in fuse block F1, in position 15, there is a 5A fuse that also supplies power to the controller.

Additionally, when checking fuses don't just rely on what you see through the sight glass. Always use a multi-meter, to check that voltage is present on both sides of the fuse and/or pull the fuse and check for zero ohms. Also check the fuse contacts for corrosion and pitting that might limit the current the fuse will pass (e.g. specially true on fuses that are required to pass high currents).

Lastly, during A208 production, 2 different N52 controllers were used, so make sure that the replacement part numbers are the same.

 

1. Is it necessary to remove fuses F4/#11 and F1/#15 when removing the N52 connector?
2. When the top is moved manually to resynchronize everything, does the ignition key need to be in any specific position?
3. Does the N52 controller observe the state of all the top switches even when the ignition is off?

Thanks as always!

 

Is it necessary to remove fuses F4/#11 and F1/#15 when removing the N52 connector?

Good question....no one has ever asked before and more then likely did not remove the fuses.

The hot side of fuse #15, in the driver side engine compartment F1 fuse box, is from a circuit 15, which only supplies battery power when the ignition switch is position 2 or 3.

The trunk F4 fuse box has 4 fuses (e.g.in position's 10 - 13 and unique to only the A208 cabriolet models), that provide circuit 30, unswitched battery power. In addition to the fuses mentioned in post #3, more then likely they provide power to the rear window motors and the RB deployment solenoid.

IMO, since the connector will just directly pull out, removing it from the the controller should not be an issue and if the connectors are keyed, not possible to plug it in with the pins out of proper alignment, that should not be a problem either.

However, it's very important to be aware the the diagram for the connector pins assignments are for the connector mounted on the controller. When you view the connector on the unattached wiring harness, you'll be viewing the pin assignments as a the mirror image.


When the top is moved manually to resynchronize everything, does the ignition key need to be in any specific position?

No.

After you unattach the controller's wiring harness, you're simply working with an unpowered passive harness and by taking resistance measurement with a multimeter, you can verify that the position/limit switches are actualizing properly, during each stage of roof operation when either opening or closing the power roof.

Electrically, the switches are quite reliable (e.g. typically rated for at least tens of thousands operations) and there have been far more issues with the mechanical mechanism that should trigger it, wiring breakage etc..


Does the N52 controller observe the state of all the top switches even when the ignition is off?

No.

However, when you turn the ignition switch to position 2 (or start the vehicle), the controller wakes up and the lamp in roof's operating switch will illuminate briefly, while it runs a built in diagnostic test, that checks the status and function of the power roof. After the test, the lamp will turn off, but if the lamp remains illuminated, flashes under specific conditions or flash rate, the controller detected a faulty condition. The explanations of the detected anomaly (e.g. the controller thinks that the compartment cover or soft top is not locked, the trunk is open etc.) have been posted numerous times.

 

If the controller does not observe the state of the switches when the ignition is off, and if you can "resynchronize" the system by manually opening and closing the top with the ignition off, what does "resynchronization" actually do, and why does one need to open and close the top?