820-00850 & 820-01949, No WiFi *In Recovery*

[ugamazing]

I've got two boards with the exact same issue, and it's confusing the hell out of me. In short:

1. Both boards behave *exactly* the same; they will show WiFi networks to connect to, and will boot fully to Internet Recovery, but they each show zero available WiFi networks once booted to Internet Recovery. I also cannot switch WiFi "off", as in, the toggle will not move.

2. Both boards will erase perfectly fine using the "erase mac" function; I can wipe them with disk utility, but if I try to install MacOS from Internet Recovery, it says to connect to a WiFi network (which of course, I cannot do).

3. Each board is 'perfect' and without any damage at all. I combed each board thoroughly for any damaged/missing components, and all PCIe caps are present on both boards.

4. I cannot find any diode values that differ between each board and another working board of the exact same model.

5. All WiFi power lines are present when measured at the coils/inductors and caps immediately by the WiFi card/chip. No shorts on any rails that I can locate.

6. I did just notice that when booted to Internet Recovery, and when checking voltages at L3702 & L3703, I get 0v with a slight bit of pulsing at L3702. I have 1.35v steady on L3701 at all times. I'm going to check a known-good board while booted to IR and see if these voltages are present. If so, I'll likely replace U3730.

7. I have restored both boards via DFU/AC2 and no change at all.

8. Each board tested in 3 different known-good casing assemblies.

I am starting to suspect a BIOS or WiFi firmware issue, but I'm very confused on how WiFi can work perfectly pre-boot, and will connect fine and boot to Internet Recovery perfectly, but then once in Internet Recovery, I cannot see or connect to any WiFi network. It's so odd.

I really am not sure how to proceed, so hoping someone might have seen this issue before? Any help appreciated!

Thank you!

[ugamazing]

Re: 820-00850 & 820-01949, No WiFi *In Recovery*

OK, so it looks like my problem is in fact related to P1V2_WLANBT_VLX and PVIN_RFLDO_WLANBT_VLX both being missing when booted to Internet Recovery. Pretty weird since they are present pre-boot. Not sure why exactly they would be missing only after booting to IR.

Confirmed a working board does have both signals present without pulsing when booted to IR.

I'll try replacing WiFi/BT IC soon and will update thread.

[ugamazing]

Re: 820-00850 & 820-01949, No WiFi *In Recovery*

Replaced U3730 and absolutely no change at all. Interesting. Also replaced WiFi ROM just in case, and no change either. Very odd problem.

[AppleExpert]

Re: 820-00850 & 820-01949, No WiFi *In Recovery*

Did you try to manually add WiFi network ??
It is a 🐛 in new recovery.

[ugamazing]

Re: 820-00850 & 820-01949, No WiFi *In Recovery*

Thanks for the reply.

Yeah, we tried everything we can think of. Manually trying to add the network fails. Can't seem to replicate this 'issue' on any boards except the two mentioned here, so suspect it's an actual fault, but I could be totally wrong.

Can you explain the bug you mention? I haven't seen it referenced anywhere and it would be good to know, just in case.

I just don't know what else to try, haha!

[ugamazing]

Re: 820-00850 & 820-01949, No WiFi *In Recovery*

OK, I think I figured this one out. And I think I understand the "bug" in IR now:

So, apparently if you do manually enter a WiFi network/password, the unit WILL connect to WiFi but it will still show the WiFi icon as not connected (gray/not lit-up). So, the unit is connected to internet, but not showing any indication that it's connected (including showing the "select wifi network or connect ethernet cable" message). So...strange, but this one is solved.

Only happens on some units. Seems inconsistent. Literally booted to IR 25+ times and got the same issue with the same two boards, and not with other boards. Manually entered WiFi network, and even though it "didn't connect", it did. So, weird.

Can close this one! Solved.