This post is simply more about adding some useful info in the archives since I'm not asking for help, but sharing my issue and fix.
The history of my printer is that from an early age, it had to have its main board and carriage replaced twice, yes, twice. It developed a problem in a channel that a new head didn't fix. So a new carriage was installed, and although it brought some nozzles back in the channel, it was still clearly bad. So then a new main board was installed, but this too didn't solve the problem. As it so happens, the original problem was more than likely the main board, and so when the new carriage was installed, the bad main board fried it. When the new board was installed, the new carriage was unfortunately already fried, so it was no good now as well, even though it was new. After a new main board, the second one, and a new carriage, also a second one, and two new heads, everything was back to normal.
Fast forward over a year, and the printer started to get this error code. "03130031-2F26" Reading the manual, it states that the carriage is inoperable and to check the surrounding parts, etc. Along with this, it also says to check the encoder strip and linear scale. There are hardly any posts anywhere with this error code, and the fix usually was the linear scale, but mine looked good.
The other error code I would get was 03130031-2F13 , which states "A/D converter external trigger output stop detection hardware error 1", and once again "Check the carriage unit and surrounding parts."
One thing I noted was that this happened less when the printer was warm. So sure enough, I kept making sure the printer was very warm before using it. If the printer stops suddenly and displays this, I would have to go into service mode, do a nozzle check, go to regular mode, have it do this test where it runs the carriage back and forth for 5 minutes or more, and hope and pray it worked. For the most part, after it got going it was fine, but it was a struggle sometimes.
Fast forward to a month ago. I read all the printer posts here and am amazed by the guys fixing their HP 3100's with the excellent help that Mark Lindquist is providing. It just so happened that I watched the video on replacing the belt, and noticed that they were oiling the carriage rod. I remember when the 2 techs were replacing my carriage unit and I asked about oiling and they said its not necessary. They were very careful to not damage it when they removed it, but all they did was install the new carriage unit after putting it back carefully. I also noticed that it had these felt pads, so I figured maybe the felt pads are pre-oiled, so each new carriage unit would also lubricate the rod.
So as I had this in my head, and looking at my error codes, I also came across some stuff that said these error codes have something to do with a timeout, or too much current draw on the motor that is moving the carriage. It always stops in the exact same place with a loud thump, but not because its hitting something, but just because the motor stops suddenly. It usually wouldn't do it during loading paper, but it would do it just before printing, and it would never do it in service mode, although all you can do is print out nozzle checks and stuff. But still, it was some kind of software thing where unless its printing, it wasn't monitoring some values. Also, given that it works much better when warm, although even this wasn't as successful after many months as it used to be, it occurred to me that maybe what is going on is that too much friction is causing the motor to work a little harder, which spikes the voltage, and bam, error code and shut down. When its warm, either the little bit of lubricant that is there is more viscous, or the parts slightly expand from the heat, just enough to make it slide smoother.
So after lots of research, I decided that sewing machine oil should be good enough. I applied it just like in the video on my carriage rod, and for a few weeks now, I have not seen the error code again. Before, it would come up almost every time before doing a print until it warmed up enough to get it going.
I figure its very rare for a carriage to be replaced twice, and so whatever lubricant is put on the rod from the factory is enough for the life of the printer, but in my case, those felt pads probably soaked up whatever was there, as opposed to lubricating it some more, and it clearly needed more. I would have liked to get the special oil, since mine is only a $6 bottle that is sewing machine oil and I'm not even sure if its 100% syntethic, but I just didn't want to initially spend $50 on a bottle, just in case it didn't help it any more. Now I'm not sure if I should get better stuff, but this is certainly doing the trick.
I hope if someone ever has this error code come up, this posts helps them out!
