Fixing the dreaded “RFU Load Error/Send RFU Upgrade” on CP3505 Using a Mac

At work, I came upon a CP3505 LaserJet printer that was displaying this error message:

Naturally, I wondered why a perfectly good printer would get to this state. I power cycled the printer which revealed the true error:


I looked this error on Google, and found many other people in the same situation with no really good answers. This printer either needed a new formatter board or an RFU firmware update. I thought it would be simple enough to connect to the printer via FTP over the network and force the update, but I noticed that there was no activity displaying on the jetdirect port on the side of the printer. Sure enough, a ping to the printer resulted in lost packets.

At this point, I knew that I needed to directly connect to the printer using a USB cable since there were no other options (besides replacing the formatter board). Using Windows XP or Vista was unfortunately out of the question because I only had access to a Mac. Looking online, I couldn’t find a single resource in order to send a firmware file to the printer. I checked HP business forums, Google, and more with little to no results. After a little experimenting, I figured out what was needed to fix the printer using a Mac. These steps are similar to using a PC, but I found that a Mac was *much* easier after everything was said and done.

1. Get the firmware file from HP’s website. It’s usually in the “Cross operating system (BIOS, Firmware, Diagnostics, etc.)” category. When you visit that category, HP usually shows 3-4 links to firmware files (Mac, Windows, UNIX, etc). Secret here is that they are really all the same RFU firmware file, just compressed using different formats. Go ahead and down the one of choice and save it on your desktop or similar location.


2. Uncompress the files and remove the old compressed file since that will no longer be needed. Once again, I placed my file on the desktop, so I knew where it was.

3. Find a USB 2.0 cable (Type A to B) and plug that into your printer (while it’s on and displaying the error message). Then plug the other end to your computer. Nothing should happen on the computer side.

4. Next, go into the “Print and Fax” System Preferences control panel .


5. Click on the “plus” sign at the bottom left like you are installing a new printer.


6. In the add printer dialog box, make sure that the default icon is selected.


7. Then, you should see a printer in the list (only one in the list) called “HP LaserJet USB Upgrade”. If you do not see this printer (or any printer), you may have a bad cable, but most likely, you’re printer is toast. Click on HP LaserJet USB Upgrade, and your computer will try finding drivers for this type of printer (at this point, your computer has no idea what type of printer this is).

8. Go to “Print Using:” and select “Select Printer Software”.


9. When the list of printers come up, select an HP 4100 series printer driver. You may be wondering why you are choosing the HP 4100 series printer driver and your original printer driver. The answer is fairly simple, it really doesn’t matter what driver you choose except that it needs to the a certain kind that allows your computer to send a regular file to a printer for processing. Most of the HP drivers will do this, to be on the safe side, select the 4100.


10. Next, you’ll want to make sure it’s set as the default printer (you’ll see why in a minute). Although my picture shows that the printer is Offline, it should be Online if it’s still connected to the printer.


11. This next step involves using the terminal. Open the terminal by going to Applications>Utilities>Terminal. You can also perform a spotlight search for it.

12. Once the terminal window is up, type in “lpr” and then a space, and then type in the location of your firmware file, or drag and drop the firmware file (called “cp3505fw_03.020.3.rfu” in my case) on to the terminal window and the OS will do the rest. This command will print a file to the default printer which is why that was set earlier.


13. Press enter, and you should start to see a progress with the printer. Once the file is transferred over, the printer will power cycle and be ready for printing. All network settings should have remained intact. Enjoy! You can remove the printer we just created by clicking on the “-” sign in the print and fax system preference panel.

Extra: For you PC users (XP and Vista), the theory of sending the firmware is the same. The main differences is the dos console and how the printer is added to the system.

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