Here is a description of how I repaired my dead FOB. All it would do was start the car; I could not use any of the buttons to unlock/lock the car. Batteries were good.
I will not describe removing the batteries as there are good YouTube videos on how to do this.
First off I cleaned the battery holder contacts and bent out the contacts to put more pressure against the circuit board. Once I had done this the lock and boot buttons made the red led flash but the unlock button was still not working. So it was time to take the FOB apart. With the batteries removed the FOB looks like the attached pic 'End View Without Batteries' (how do I embed pics??).
To remove the circuit board you must first remove the piece of white plastic that is holding the board in place. After some fiddling around, I gripped one end with fine-nose pliers and it pulled out quite easily. See pic. There is a rigid wire behind it that locks it into place in the FOB but if you pull with the pliers it comes out with no damage.
The circuit board can then be pulled out. It was a bit tight so again I used fine-nose pliers to pull on the middle of it where there is a wide stretch of plating for the battery contact. When I got the board out it was in quite a state. Covered in a brownish, flaky, crystaline crud which I presume is where the flux had not been properly cleaned off the board when it was manufactured (poor quality) and had reacted with the board coatings. Maybe this wasn't helping things ! As I had no isopropyl alcohol which I think is the proper stuff to use; I instead used some switch cleaner spray and then a brush and methylated spirit to clean the board; finishing off with a low temp hair dryer to remove the meths residue. See pic. I also cleaned the area on the circuit board that the battery contacts with wet n'dry as it was very dull and oxidised.
When I tested the unlock button with a DVM, it read open-circuit when pressed and hence I concluded that this switch was faulty. I sourced a replacement microswitch on eBay having the same dimensions though looks a bit different. I took the old switch off using a soldering iron at each end to lift it off. Then I attached the new microswitch making sure it was positioned in the right place and sitting flat on the board (see pic).
Put it all back together and now I have a working FOB except that the RF is not working so I have to open/lock the doors using the IR (aim it at the door handle within a foot or so) but I am pleased to have an otherwise working FOB as they are £227 from MB.
Anyone know if the RF needs to be sync'd up somehow or do you think it's just dead?
Anyone else found the FOB pcb to be covered in crud?
Hope this is useful. If I knew how, I would have embedded the pics but I hope they have attached OK.
I will not describe removing the batteries as there are good YouTube videos on how to do this.
First off I cleaned the battery holder contacts and bent out the contacts to put more pressure against the circuit board. Once I had done this the lock and boot buttons made the red led flash but the unlock button was still not working. So it was time to take the FOB apart. With the batteries removed the FOB looks like the attached pic 'End View Without Batteries' (how do I embed pics??).
To remove the circuit board you must first remove the piece of white plastic that is holding the board in place. After some fiddling around, I gripped one end with fine-nose pliers and it pulled out quite easily. See pic. There is a rigid wire behind it that locks it into place in the FOB but if you pull with the pliers it comes out with no damage.
The circuit board can then be pulled out. It was a bit tight so again I used fine-nose pliers to pull on the middle of it where there is a wide stretch of plating for the battery contact. When I got the board out it was in quite a state. Covered in a brownish, flaky, crystaline crud which I presume is where the flux had not been properly cleaned off the board when it was manufactured (poor quality) and had reacted with the board coatings. Maybe this wasn't helping things ! As I had no isopropyl alcohol which I think is the proper stuff to use; I instead used some switch cleaner spray and then a brush and methylated spirit to clean the board; finishing off with a low temp hair dryer to remove the meths residue. See pic. I also cleaned the area on the circuit board that the battery contacts with wet n'dry as it was very dull and oxidised.
When I tested the unlock button with a DVM, it read open-circuit when pressed and hence I concluded that this switch was faulty. I sourced a replacement microswitch on eBay having the same dimensions though looks a bit different. I took the old switch off using a soldering iron at each end to lift it off. Then I attached the new microswitch making sure it was positioned in the right place and sitting flat on the board (see pic).
Put it all back together and now I have a working FOB except that the RF is not working so I have to open/lock the doors using the IR (aim it at the door handle within a foot or so) but I am pleased to have an otherwise working FOB as they are £227 from MB.
Anyone know if the RF needs to be sync'd up somehow or do you think it's just dead?
Anyone else found the FOB pcb to be covered in crud?
Hope this is useful. If I knew how, I would have embedded the pics but I hope they have attached OK.