Ender 3 S1 Pro Thermal Runaway

Just installed new motherboard, new hot end, flashed the firmware in the touch screen and still getting ‘Thermal Runaway’ pop up when the nozzle starts heating. Following the instructions provided by Creality I tried to update the firmware via the motherboard slot, and nothing happens.
What am I missing?

Do you have a spare thermistor?
It’s a pretty common problem when people change their hot end that the tiny wires in the thermistor break. They’re super delicate and a broken one would cause a thermal runaway error.

I have a second S1 Pro that’s working so I’m going to swap out extruders. It also has a new hot end and just completed a lengthy print, so it’ll be interesting to see if the same thing happens.
Stay tuned!

Swapped out extruders and same thing, nozzle does not heat up and goes into thermal runaway. Now I need to figure out what else can cause this besides a faulty hot end/thermistor.

Before trying to heat the hot end does the temperature read as your ambient room temperature?

If not, bad thermistor, but if it does then we move onto other scenarios.

It could possibly be a bad fuse on the board as well. If the board is trying to heat but the thermistor isn’t reading any change in temperature it will throw an error.

I had a fuse go bad on a new board almost immediately after installing it and ran into the printer throwing an error when trying to preheat and from what I remember it would reboot each time too.

Both bed and nozzle are showing the same temp, 22C. Fuses in both motherboards look OK. Earlier today it actually started printing with a good purge line and the start of the model. But it didn’t take long for the nozzle temp to start going down to where it wasn’t melting the PLA anymore, so I shut the print down. The saga continues!

You could replace the fuses anyway if you have spares. When mine did that it started off by still heating part way before throwing the error until eventually it just stopped heating all together. It might not be the problem but its a cheap and easy enough thing to do to rule out that as the cause.

Was the screen showing that the temperature was dropping?
I’m curious if the printer is aware of the temperature drop or if it somehow thinks it’s still hot enough.
If it was showing the temperature drop I would be inclined to think that it recieved a command to do so in which case maybe check the gcode file for any rogue temperature commands after the initial heating one.

If you just preheat the hot end without starting a print is it able to maintain that temperature or does it still thermal runaway? If it does then we know it’s not the print file.

I’m grasping at this point to figure out the cause but sometimes a bit of dialogue can help.

Is there a way to tell if the fuse has blown? The ones on both original and new motherboards look intact.

Yes, the print was running fine, and then the temperature started to drop. That’s the maddening part, everything else is working as it should. I even re-installed the original motherboard, did a firmware update via the micro-SD in the touch screen and it now works again just fine.

When doing a PLA pre-heat, the nozzle doesn’t heat up at all. The temperature stays constant or goes up and down one degree, the bed heats up as it should. After a few seconds of this the machine shuts down along with the thermal runaway pop up on the touch screen appearing.

Since it did work once, I can’t help but wonder if there’s a lose/broken wire somewhere in all the spaghetti inside the thing. I had a messed-up BL Touch on a CR 10 a while ago and could not figure out what was wrong, even after the Pronterface diagnostic told me the BLT was messed up. Then by pure accident I slid the plastic tube that held all the wires going into the extruder/hot end up a several inches and there as plain as day was a broken wire that was part of the group hooked up to the BLT. Interesting example of not seeing the forest for the trees.

Hello!

One idea I have is that there is possibly a problem with the plug on the end or the cable. Can you unplug it from the motherboard and take it entirely out if possible, check for any breaks or possible locations for shorts in the wire. Finally check the plug on the end and make sure everything looks ok, if you have a multi-meter you could also check the continuity in the cable. When checking the continuity try moving and flexing the cable around and see if it starts to disconnect.

Hope this helps,
Matthew

Hi Matthew,
I have not tried that, but it makes sense especially since it did almost work like it should and then fizzled out and shut down.
Thanks!
Les

No problem!

Please feel free to get back to me if you have any other problems with the printer.

Hope this helps,
Matthew

Sounds good, thanks! I haven’t had a chance to take it apart yet, stay tuned!
les

Hi Matthew,
Quick update…I have a couple of S1 Pros so I swapped out the complete extruder with one that I know works and has a new hot end. Fired up the Pre-heat PLA and watched as the nozzle temp did not change. Then I wiggled the cable where it enters the extruder and suddenly the temperature started going up just as it should. When I released the cable and let it sit, the temperature held for a second or two and then started going down. Wiggled the cable, it went back up and after several of these it had enough and went into thermal runaway and shut down. Soooo, this begs the question; is there a busted wire or something wrong with the cable? I’ll take the bottom off over the weekend and start checking the cable to see if there’s anything visible.
The saga continues!
Les

Thanks for your response!

That is interesting for sure. When you switched over the hotend you knew worked properly did you also switch the thermistor and heater cartridge, or did you keep the same ones as before?

I think its a good idea to inspect the motherboard next! Look all around where the thermistor and heater cartridge plug in to see if anything looks fishy. I would also inspect the rest of the board for any damage.

Thanks again!
Matthew

Hi Matthew,
Welcome! I left the hot end in the extruder, it’s new and had just finished a print not long before making the switch. I’ve got a new motherboard which I’ll install when I take it apart over the weekend. I’ll also do a firmware update and we’ll see what happens. I have never run across this. As we like to say in the wonderful world of academia; this is a teaching moment!
Les

Hi Matthew,
So the saga continues. Looks like the problem is in the cable where it clicks into the extruder. I braced it after my last post and it was working fine until last night when the thermal runaway pop up came back. After wiggling it, it ran fine. I got a new extruder a while back and had the same issue, so it’s not the extruder. When time allows, I’ll look around for a new cable and replace the one that’s in there now.
Stay tuned!
Les

Oh no!

Looking for a cable replacement seems like a good idea. You may also want to check the cable to see if there is anything that looks wrong, the cable is inside of a sleeve but run your finger along it and see if there are any kinks or breaks in the cable.

Depending on how long ago you bought the printer you may be able to contact creality and get a new cable from them as well.

I wish you luck in getting this working!
Matthew

Oh yes! But I found the problem, it was the ribbon cable all along. The first four wires on the right-side of the cable are busted. This explains why with some wiggling it would work and then fizzle out. I’m probably very lucky that my wiggling didn’t cause a short or something worse. This is interesting because when I was putting the printer together, I noticed how very badly the cable at the extruder end was crimped during packaging. And I had a hunch that if anything electronically would go wrong, this is where it would happen…and it did.
Les

Perfect, glad you were able to figure this out!

My next step would be to contact creality support directly. They should be able to assist you in getting a new cable for your printer. Its possible you may need to pay for it, but depending on when you bought the printer they may also send it to you for free.

Happy printing,
Matthew

I need to check when I got it. Either way, free or pay, it’ll be good to get it running again. There are lots of folks waiting for their prints!
Les