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Modelo A1237 o A1304 / 1.6, procesador 1.8, 1.86 o 2.13 GHz Core 2 Duo

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Where is the battery sensor in an A1304?

I have a problem with a MacBook Air 2,1 A1304.

The MacBook runs fine from the power supply, but the battery will not charge and the computer will not run from the battery (even though a battery is present, working, and has over 60% charge). MacOS shows no battery present.

Running Mac Hardware Test results in error code:

Error code: 4SNS/1/40000001: TB1T-0.000

This is a temperature sensor error and - I presume - therefore the battery temperature sensor?

The question then is what, if anything, could be done about this?

I have searched widely but cannot find where the battery temperature sensor is located on an A1304. Any tips most welcome!

These photos illustrate the problem:

Coconut Battery - note the temperature!

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No battery recognised in MacOS

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System Report

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But when booting with Ubuntu...

Battery is recognised - and has charge, but is NOT charging (MagSafe shows green LED)

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More detail

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Further update

The question was raised below if this was simply a battery problem. No - the same happens with other batteries I have tried, and the batteries are new or new-ish. These two screenshots show Coconut Battery and the Ubuntu battery overview - but with a different battery installed. The same faulty temperature reading in Coconut Battery.

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Contestado! Ver respuesta Yo también tengo este problema

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Lets install this gem of an app: CoconutBattery and paste the main window here for us to see Agregar imágenes a una pregunta existente It will allow us to see whats happening a bit better.

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Hi Dan - Thanks! Photos now added. Data from both MacOS and Ubuntu.

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@jonworth remove the battery and run the AHT and see what code you get. I am not convinced of this being a sensor error. If your MB does not recognize your battery it is possible that the sensor will give you erroneous results. What is the 820-xxxx number on your logic board? What happens if you unplug the Magsafe from your MBA while it is running?

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@oldturkey03 Thanks for the reply! See also the discussion with @arbaman under his answer below. This looks more like a SMC problem than a battery problem in the end.

I have just run AHT again, without a battery, and that gives the very same error:

Error code: 4SNS/1/40000001: TB1T-0.000

So I think we can eliminate battery problems, and limit it then to SMC issues...

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@jonworth that is correct and that is what my expectation was. I really don't care about the battery. I am not after the battery at all but trying to determine if it is the sensing circuitry between your battery and the SMC that has failed. For as long as your MBA does not recognize the battery it will most likely have issues with the sensor as well.

Would you mind to humor me and let us know what happens if you unplug the Magsafe from your MBA while it is running?

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Solución Elegida

It seems to be just a dead battery, with faulty logic unable to exchange data with Mac's system management control IC. Battery temperature sensor is in the battery, not on the logic board. The other possible explanation of the issue could be a faulty SMC, but if the battery is very old or a new replacement a battery fault would be the logical explanation.

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Thanks.

The battery is new. And I have also tried another new battery - and that behaves just the same way.

I have tried to reset the SMC, but this makes no difference. What is the best check to do to see if there is a SMC fault?

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Photos of what I get with a different battery installed have now been added at the bottom of the question above!

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Logic board charging problems involve a fairly deep level of troubleshooting at component level..fact that the Smc is not working properly might involve quite a number of parts..charging/power Ic, sensing resistors, capacitors and so on. In few words it needs schematics, boardview and testing one by one all related power and data lines to determine what's wrong and the ability and parts to replace it. Given the present value of a working 2nd hand logic board, I'd recommend a replacement as the most economical approach.

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I'm tempted to think the same, yes :-)

And it does look like the SMC being the problem. This from the logs when booting in verbose mode:

Jun 18 19:17:06 localhost kernel[0]: SMC::smcInitHelper ERROR: MMIO regMap == NULL - fall back to old SMC mode

Jun 18 19:17:07 iMacs-MacBook-Air kernel[0]: SMC::smcReadKeyAction ERROR: smcReadData8 failed for key MOTP (kSMCKeyNotFound)

Jun 18 19:17:07 iMacs-MacBook-Air kernel[0]: SMC::smcReadKeyAction ERROR: smcReadData8 failed for key BEMB (kSMCKeyNotFound)

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@arbaman don't give up so soon ;-) How about checking the isense circuitry etc. to see if the MBA even sees the battery? Check to make sure that the board gets power from the battery. Something as benign as a failed ferrite bead near the battery connector could be the issue etc. Remember we want to keep things out of the landfill. So right now the OP has nothing to lose and a whole lot to gain. At least maybe some experience as well. :-) Shoot me an email if you need to take a look at the schematic

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Do as @oldturkey03 recommends. I’m suspecting your battery has a problem.

Do make sure you are using a real Apple MagSafe charger and the cable & connectors are in good shape. Review this great Apple T/N: Apple Portables: Troubleshooting MagSafe adapters

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Thanks - I have indeed done what @oldturkey03 suggested, and I get the very same error in AHT:

Error code: 4SNS/1/40000001: TB1T-0.000

When there is NO battery at all in the machine.

So this - and in addition my response to @arbaman above with the log from Verbose Mode - makes me think this is a SMC issue, not a battery issue.

Resetting the SMC makes no difference.

Is there any way to force reset the SMC or flash it somehow?

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Please check the MagSafe adapter and the connector on your system. Are the connections clean and in good shape?

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Yes, the MagSafe is all fine. And the computer - without a battery - runs without any sort of glitch from the MagSafe. Plus the battery has 56% charge, so the Mac ought to run from the battery even were the MagSafe faulty, but does not.

The MagSafe, when plugged in, is green for about 1 sec, then orange for about 3 sec, then back to green again, and stays like that.

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I was aiming you to inspect the connector faces. Are they clean and shiny? I was mostly concerned with the middle pin.

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Did you have a liquid spill at some point into the keyboard or trackpad?

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Jon Worth estará eternamente agradecido.
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