Member Avatar for Lionel_1

Hi all.

I have a Toshiba Satellite Notebook U920T PSUL1A-01Y001

While I had the laptop opened up to replace some parts, I accidentally pulled the delicate hard connection off the back of the NFC module (pulled the flex cable off the module). I don't use NFC so I left it unattached, closed it back up after the repairs.

Upon booting it said RTC battery is low. I replaced RTC battery. Booted up and said RTC battery is low. Press F2 to (do something). I pressed F2, also Function+F2 and it does nothing. It won't let me press anything.

Would this broken connection be breaking the circuit, or is it something else. There appears to be a white (earth?) wire attaching to the NFC module on the other side.

Thankyou for any information,

Lionel

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Brief summary: the RTC-low warning here was resolved when replaced and reseated the NFC module. That outcome makes it likely the board was flagging a missing/poorly-seated submodule or a damaged flex/connector rather than the coin cell itself. The following concise checklist and tips will help anyone who sees the same symptom.

  • Measure the RTC battery with a multimeter (DC volts, 20 V range). A healthy coin cell reads about 3.0–3.3 V no-load. Treat readings under ~3.0 V as exhausted.
  • If the battery measures OK, visually inspect the flex cable and connector for torn traces, bent or crushed contacts, or glue/metal debris that could short a detection line. Clean contacts with isopropyl alcohol if dirty.
  • Verify you can actually reach POST/BIOS: try an external USB keyboard, remove all peripherals, and power-cycle. Some firmwares use fast-boot and will not accept keys unless USB devices initialize early.
  • Try a CMOS clear: power down, unplug AC, disconnect main battery, remove the RTC coin cell for 5–10 minutes, then reassemble and test. Follow the service manual for any jumper-based reset.
  • If the OEM battery/harness is costly, use a prewired CR2032 holder or transplant the original connector onto a fresh coin cell harness. Avoid prolonged heat on the cell when soldering, and always respect polarity.

Safety notes: work with power removed, observe ESD precautions, and do not substitute higher-voltage cells. ’s advice to measure voltages and reuse the harness is practical and cost effective.

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Member Avatar for rproffitt

My thought here is to replace what's broken. Getting an answer from the maker to "what happens when the cable is broke to the NFC?" is unlikely. I don't want to tell you how much that module will cost as costs change from mass production to FRU.

My other thought is that over the years I've seen way too many error messages that were incorrect. So the BIOS might actually be seeing the missing module and the error message is incorrect.

Finally, what voltage is the old and new battery? A Volt meter is not optional for repair work today but you will find techs missing that and a few screws loose.

Member Avatar for Lionel_1

G'day rproffitt,

Thanks for your reply!

I threw out the old RTC battery and replaced it with a genuine 3V Toshiba RTC battery P000563990. $5.62
Edit: I will test the voltage when I open her up again. It may be a lemon.

The genuine NFC Module P000564050 is a measly $14.04.

I read somewhere that when the main battery is cactus, it gives the same warning. I don't see how that would matter if the power supply is plugged in.

I will go ahead and order a new NFC Module after I have moved house next week. The trouble is I can't find a photo of the part to see exactly what I'm buying.

Any further feedback is welcomed.

Thanks,

Lionel

Edited by Lionel_1 because: Add text
Member Avatar for rproffitt

I wonder about that RTC battery. Remember I'm an electronics designer among other things so I went looking for why a 3V cmos battery would be over a dollar.
https://www.google.com/search?q=P000563990&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjyk7CnqaLVAhWFllQKHQo4AGAQ_AUIDCgD&biw=1536&bih=731

It looks like a classic CR2032 battery in some cases and in others where some prongs were added or a cable. That is possibly why it's more than a dollar. We keep a pack of CR2032's on hand and get them in bulk.

If I ran across one with a cable I can replace the battery and reuse the cable. Little snip snip, solder and electrical tape and I'm done for a dollar.

Call me cheap.

As to the module, let's hope that clears it all up.

Member Avatar for Lionel_1

Cheap is good. I'm hearing what you're saying... I'll take myself down to the electronics shop and get a tiny connector and make up a little battery, if the voltage isn't right. I'll also send an email to the parts supplier.

I wish I had kept the old battery to cut it off and use the wire on a CR2032. The genuine part is the orange Lithium- Ion battery shown first.

I'm looking forward to getting on top of this in a couple of weeks.

Thanks mate.

Edited by Lionel_1
Member Avatar for rproffitt

The everyday cr2032 is Lithum and other materials.
http://data.energizer.com/pdfs/cr2032.pdf points out the nominal voltage and I've seen these come in hot at 3.3V no load so there's about a 10% varience or more.

For me I call them gone with they are under 3.0V no load.

Member Avatar for Lionel_1

Well the problem is all fixed.

I ordered the NFC Module. That fit wonderfully and fixed that little problem.

I also accidentally got another RTC battery. It must have made it into my basket and I overlooked it

Edited by Lionel_1
commented: Thanks for the final report. Sometimes you have to fix the broken bits. +12
Member Avatar for Lionel_1

For some reason it didn't post up in full. I'll try again now.
Well the problem is all fixed.

I ordered the NFC Module. That fit wonderfully and fixed that little problem.

I also accidentally got another RTC battery. It must have made it into my basket and I overlooked it

Edited by Lionel_1
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