Sleep mode in LaserJet Pro MFP M479fdw is not working after firmware update

[AlexeyO]

Hello..

I have just upgraded the firmware of my LaserJet Pro MFP M479fdw to CLRWTRXXXN002.2149A.00.

After the upgrade the sleep mode is not working any more - printer screen is always on, and the printer is humming constantly,

Please, help to fix.

[Repairatrooper]

In terms of a fix, typically HP is the last to know when things don't work, users do not always contact support and create a case so it can take months for an issue like this to come to their attention. We have lots of these in the field with our customers and I have not yet had this issue raised so it may not be affecting all M479 products. Have you checked the settings to ensure they did not get reset or turned off when the update was done.  I have also notified the moderators of this board and asked them to forward this to the proper team at HP.

[AlexeyO]

Thank you a lot for coming back. In fact, this is the first thing I checked - that the settings are intact. I had sleep mode set to 1 min - it is exactly what I found. To be sure I tried to select other options, like off, then 5 min. Did not help - the device never goes to sleep.

I was thinking to do a factory default reset, but did not have time for this yet, plus decided to see, whether I get some feedback here. Thank you for the message forwarding.

[brian513]

I had the same issue. Printer updated overnight at some point. When I went into my home office in the morning, the printer was online like I had just printed something and it stayed like this until I power cycled it. It would not go to sleep.

In order to resolve it, I did a factory reset. I did have to setup the network and other preferencese again, but it has not happened since.

[AlexeyO · Accepted solution]

You were just ahead of me 🙂 I wanted to report, that I too have done factory reset, and that fixed the issue in the end. However there was an extra factor in my case (see below).

SHORT SOLUTION DESCRIPTION: Factory default reset and fixing fax cable connection.

Long description: Someone from my household (well, I know who :)) "disturbed" the phone cable in the fax port. The result was, that from the side of the line connector, the cable become "semi-attached", i.e. I got classical "contact chatter". This happened a while ago, before the firmware upgrade. Previous firmware was just ignoring this, but the new one seems to "care", so the printer would go to sleep, only to immediately wake up and never go to sleep after.

So when I did factory reset, and the sleep still did not work, I spotted the issue while manually re-configuring different parameters and spotting the fax cable issue on the way.

Properly attaching the fax cable finally solved the issue.