355 Convertible Top Control Module Repair

You can do that with the seat out. Note that I edited my last message.

 

I guess one possible way would be to get a reading from your passenger seat and compare them (seat fully forward).

Check outer pins first to see if the wiring is ok for that.

 

This might be difficult, because I don't know what your wire colours are. Typically, the colours on the potentiometer itself are brown, yellow and pink. You'll have to match up your modified harness to these colours.

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If you have no access to the white plug on the passenger seat, then we will have to come up with a ballpark figure based on your driver's "outer" pin resistance reading.

 

Which position is the light yellow in? It's hard to tell from your photo.

 

Matching wire colours is going to be a headache on your car.

Comparing these photos...

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Your black (and I think brown/white) corresponds to the standard pink.

 

So...
Standard pink ("top" in photos) = black = brown/white
Standard yellow (middle)= Dark Yellow = ???
Standard brown ("bottom" in photos") = Light yellow = ???

Can you get continuity readings/colour matches at the splices without cutting the splices?

 

Thanks, that clarifies things.

For future reference, could you add the labels "B16" to the two grey/yellow wires in your drawing, "B19" to the Grey/blue wire, and "D5" to your two black. These labels are Roof ECU plug and pin numbers.

 

Maybe before cutting the wires, can you do a resistance check on the:

1) potentiometer light yellow and black wires (or any corresponding wire colours further downstream). This will give you the type of potentiometer (5k?)

2)potentiometer yellow and black wires. Should be near value "1)" with the seat fully forward.

3) potentiometer yellow and light yellow wires. Should be minimum with the seat fully forward.

In theory, 2) + 3) should equal 1), but due to the vagaries of resistance measurement, you might find theory doesn't match reality.

 

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You can use these values, but there can be variations from car to car. Aeroengineman used "standard colours". My colours vary from his colours and your colours.

For reference:

 

If your tech has the old Ferrari SD1 tool and your pot hasn't been moved too much out of its factory position, he can fine-tune it, but you really need to take measurements before you put your seat back. If you get mid seat position resistance values with your seat fully forward, you will probably have issues with calibration/seat movement.

 

In theory, the light yellow and black should be higher than yellow and black, but I doubt it will be an issue. A 20 kohm meter range isn’t the most accurate.

Re-splice and fit the new plug and you’re good to go, but, to be honest, no one will notice your trailer park plug and it has smooth edges, so it’s unlikely to snag on the carpet.

Your tech can fine tune the seat calibration.