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E46 Convertible
The E46 vert forum. Talk about dropping your E46 top here.

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Old 06-28-2011, 11:21 PM   #1
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Join Date: Nov 2009
Location: Georgia
Posts: 35
My Ride: '01 330Ci Vert
Exclamation Convertible Top electrical troubleshooting tools

I just finished repairing a broken wiring harness on my wife's car with help from info found here and other places and would like to put the resources I found in one thread. The mods can even sticky this one if they like.

The BMW TIS/ETK system can be found various places on the web. It will have instructions on how to work on the top and part numbers if needed. Here's just one place I used;

Here's the BMW wiring diagram system; (better than the one above)

I've attached a pdf of the CVM pinout diagram, with notes. I've listed the wire colors for the connection to the convertible top harness and noted the device numbers from the top manual where possible.

Here's my advice if the top is not working. Take it to someone that can read the codes, even if you plan on doing the work yourself. Pay the diagnostic fee and be happy. Otherwise you're completely in the dark.

Now for the real work!

1. All the sensors (except for the storage compartment floor/S239) are Hall-effect sensors and will have some resistance on them regardless of position. They have no moving parts and have a low failure rate, so if the software diagnosis is a bad sensor/valve/motor, it's very likely there's a broken wire.

2. Now you or your mechanic will have to remove the back seat and rear left passenger armrest and trim panel to access the CVM. For the next check, unplug the top harness (white connector) from the CVM and check for resistance on matching pairs according to the diagram. Start with the one that was noted bad in the software diagnosis. All the sensors and solenoid valves on this harness should have some resistance on them.

3. If any of them show an open circuit it's time to get serious, as the next step requres you to start taking stuff apart. The next step is to disconnect the questionable device from the harness and test it, and if it's bad, replace it.

4. If the device tested is not open circuit that means a wire is broken in the harness. You'll have to get some extra wire and check continuity on both wires to the pair in question to determine which one is broken. Once you find it, it's up to you if you want to split the harness and look for it. I bought some 18ga black automotive wire and ran a jumper along the length of the harness from the top latch sensor all the way to the CVM connector.

1. My experience was with the top harness but similar techniques can be used on the other harnesses connected to the CVM.
2. Remember that the windows and storage compartment cover are controlled by the general module, so when you push the up or down button, control is handed back and forth between the GM and the CVM twice per cycle.
3. Don't let someone sell you new top latches just because there's cracks in the plastic jack-screws. The plastic is cast onto the end of a metal bar. The metal bar has two holes drilled through it so the plastic is cast through the holes and it won't fall off!

If you have or find more tools for troubleshooting the convertible top feel free to add it here. If you find mistakes in my information please point it out.

Attached Files
File Type: pdf BMW convertible top info.pdf (750.2 KB, 10044 views)
File Type: pdf Convertible harness pinout.pdf (97.9 KB, 6281 views)

Last edited by Solidjake; 09-23-2012 at 02:39 AM.
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