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Advice needed...

I was installing GT3 seats in my 03 C4S and it went smoothly on the passenger side, BUT I ran into an unexpected "little black box" (535 on it) under the driver seat with another black box module on the underside of the driver's seat :huh: both wired together. Since my car has memory seats, power lumbar adjustments (but no heating) I assume these are the controls for these.

Are they easily removable?

Will disabling or removing them change anything else (remote releases, alarm, etc) or cause any warning lights to come on (like the seat buckle module)?

Thanks in advance.

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Thanks Loren.

Obviously the "535" box has to stay in the car. I had a feeling it was the central locking and the alarm...it seems like under the drivers seat is a common location for these in many cars.

Is the other module on the seat easily "unplugable" from the rest of the system (to take the seat out). Unfortunately there is not much room in the car to twist the seat around easily to check this out. Hopefully you or someone else has some easy advice on this.


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Is this what it looks like?

If so then you can disconnect the harness from the control module underneath the seat.

This is from memory so some of the details may be off

First remove the front plastic bumper shaped piece. It slips on and is retained by two platics nubs that sit in holes in the metal bracket that is a part of the metal seat frame.

Then undo the two brass colored torx screws that hold the module to the seat.

There are two connectors that need to be disconnected.

The first is a regular plastic 4-8 pin ( I do not remember exactly how many pins) one that comes out easily. The second is a 20 pin or so PC board type connector. I seem to remember there being a plastic U-shaped locking piece on this one but I could be wrong. This one pulls up from the module and is quite tight.

If you need more details let me know.



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Thanks for the info.

Yes, under the seat it does look like that. I've seen many pics of turbos etc with the GT3 seats put in so I assume there has to be a way to remove the stock seat (and associated black box) leaving the "535" box controlling the alarm, central locking, etc intact.

Unfortunately seeing under the seat while in the car is a little bit of a pain in the ***. I'll take a look again this weekend (the stock seats are back in the car), and see "what's up". (no pun intended)

Once again...thanks.

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  • 3 weeks later...


You were right, but I did not have to take off the small plastic "bumper" though...just lifted the front of the seat, took out the 2 torx screws on the seat control module, and flipped it upside down to remove the 2 cables with the "computer" and 6-pin connectors.

The ONLY problem I had was that the seat belt anchor on the driver's side Brey-Krause bracket, was not machined/tapped quite correctly, and stripped the seat-belt mounting bolt (no I didn't cross thread it!), but luckily I had spare bolts and a dremel and corrected the problem.

Thanks for your help.

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