[ashkanvafaee2]

About a week ago, my comfort access stopped working. Bimmerlink shows 1 code:

80410B: Driver's door or side antenna (FT): open circuit.

I removed the driver-side side skirt and inspected the 2 wires going into the CA antenna. The wires seemed fine (no fraying or animal chewing). Antenna pins seemed fine too.

I disconnected the antenna from the 2 wires then did a continuity test on the antenna and was able to get a signal. I did a voltage test on the 2 wires and got about 0.05v (but fluctuating). Anyone know if that's right?

Other details:
- I get the "Comfort access limited" warning on idrive
- Although it only complains about driver side, passenger side CA also stopped working at the same time
- I tested remote battery and car battery voltage, both are perfect
- Although bimmerlink says open circuit, when decoding online, the code can also be for short cirtcuit


Before I buy a replacement antenna, is there anything else I should check? (e.g. fuses, another way of checking if the antenna really is the issue?) I guess I could swap driver and passenger side antennas and see if I get the complementary code:

80410F: Aerial, passenger side: line disconnection

Thanks in advance!

[Wires]

I'd swap L to R side first to confirm. Just in case it's an issue with the comfort access module, and not the antenna.

[ashkanvafaee2]

I swapped driver and passenger side antennas. Same error appears (80410B).

As a sanity check, I disconnected passenger side antenna (while keeping driver antenna connected) and got both 80410B & 80410F. After re-connecting, we're back to just 80410B.

So antennas seem fine. I think I'll need to trace driver-side antenna wires from side skirt to wheel-well to make sure there is no damage to the wires all along this path.

I did check voltage for the 2 wires going into the passenger-side antenna and get the same ~0.05v (fluctuating) as the driver-side. I'm not exactly sure what these 2 wires correspond to (power & ground?, signal & ground?). Hopefully inspecting driver-side wheel-well will give me more hints. Any fuses specific to driver side comfort access antenna I should be checking?

[ashkanvafaee2]

I pulled back driver-side wheel well and inspected the 2 wires for the antenna. Everything looked fine.

I disconnected battery and did a continuity test on the 2 wires for the driver and passenger side antennas. Did not get a signal on either one. Checked the resistances and both read about 300k ohm.

It looks like both antenna and wire are fine.. which leaves the comfort access module. I'm still skeptical if this is the real issue though. Anyone else run into this problem?

[ashkanvafaee2]

A small update:

I found the pin info for the FEM module where the CA antennas connect to from here (scroll down).

I accessed the FEM module in the passenger foot area and performed a continuity test from the passenger side CA antenna (the working side) to pin 10 & 28 of A173*9B. Did not get any signal on either. In fact, I tested literally all the pins on all the connectors (A173*7B, A173*8B, etc) and got nothing...

I disconnected battery during all of these tests. I double checked all wires and performed the tests multiple times. Anyone has any experience testing continuity from these pins? These results are very puzzling lol. From 2016 onwards, did the pin assignments for the FEM module change? Any common mistakes that people make when doing continuity tests?

[ashkanvafaee2]

Update! I got comfort access working again! The problem was indeed a broken wire in the side skirt which connects to the comfort access antenna on the driver side.

The broken part was somewhat hidden so didn't see it on first inspection, but after carefully looking at each part of the wire, I clearly saw the disconnection. May have been due to animal chewing or some other factor. After soldering a wire to reconnect, comfort access was restored.

Fortunately I did not have to replace the comfort access antenna or FEM module but for future viewers, keep these possibilities in mind. If anyone else runs into this issue feel free to revive the thread or DM me. I am now basically an expert on all things related to comfort access lol

[TravisBGolf]

Originally Posted by ashkanvafaee2

Update! I got comfort access working again! The problem was indeed a broken wire in the side skirt which connects to the comfort access antenna on the driver side.

The broken part was somewhat hidden so didn't see it on first inspection, but after carefully looking at each part of the wire, I clearly saw the disconnection. May have been due to animal chewing or some other factor. After soldering a wire to reconnect, comfort access was restored.

Fortunately I did not have to replace the comfort access antenna or FEM module but for future viewers, keep these possibilities in mind. If anyone else runs into this issue feel free to revive the thread or DM me. I am now basically an expert on all things related to comfort access lol

Thanks for updating the thread with all your findings and ultimately a resolution. It's this kind of thing that makes these forums so valuable!

[F32_4FORTY]

Do you happen to know the precise location of where the wiring was messed up? Was it it in the actual side skirt or was the wiring messed up at a different location by the wheel well or some sort?

I’m running into the same issue it shows that my driver side antenna and trunk antenna code.

Originally Posted by ashkanvafaee2

Update! I got comfort access working again! The problem was indeed a broken wire in the side skirt which connects to the comfort access antenna on the driver side.

The broken part was somewhat hidden so didn't see it on first inspection, but after carefully looking at each part of the wire, I clearly saw the disconnection. May have been due to animal chewing or some other factor. After soldering a wire to reconnect, comfort access was restored.

Fortunately I did not have to replace the comfort access antenna or FEM module but for future viewers, keep these possibilities in mind. If anyone else runs into this issue feel free to revive the thread or DM me. I am now basically an expert on all things related to comfort access lol

[ashkanvafaee2]

Originally Posted by F32_4FORTY

Do you happen to know the precise location of where the wiring was messed up? Was it it in the actual side skirt or was the wiring messed up at a different location by the wheel well or some sort?

I’m running into the same issue it shows that my driver side antenna and trunk antenna code.

Yes, this actually occurred for me both on the driver and passenger sides. On the driver side, the wire cut was along the side skirt. For the passenger side, the wire cut was in the wheel well. So check both locations.

For the wheel well, you can access it more easily if you turn the wheels.