Hot end cools in the middle of a print

My hot end keeps cooling down in the middle of prints. I can get about 5 hours out of it then it just cools down. The information screen shows that it is room temperature and that the target temp is 230. I assumed it was the resistor so I replaced it but it is still happening. When I test with a multimeter there is no power at the resistor, no power at the connector and no power before the connector. There is power on the orange side but none on the red. If I shut down the printer and home the TAZ, the hot end still wont heat up until I touch the red leads with a multimeter. It then starts heating up, but will only work for a short time.
Please help.

Make sure that the printer is powered down and disconnected from the computer before testing. How does the board look? Do you have clip on test leads you can use? If so, you can see if voltage is detectable coming out of the connector at the board- more specifically from the connector labeled heat 0 in this diagram. How do the components under that connector look?

Check you connector from the hotend to the harness make sure it doesn’t feel hot or shorting.

I had the same problem. This thread may help: https://forum.lulzbot.com/t/temperature-drops-after-print-starts/1020/1

The board looks fine. I tested the extruder heat 0 and it tested fine. I still get the same results. The end will not heat up unless I put a multimeter on it. It heats as long as its on there but as soon as I remove the multimeter the temp drops, which means it must be losing current at that point. BTW should I be getting a fluctuating reading of between 5.5 and 7.2 on the multimeter?

Do you mean it won’t heat up unless you touch the thermistor leads?
Buda2.png
Themistor - Yellow Arrow
Resistor - Purple Arrow

Where the print head connects to the main wiring loom coming from the control box. Where the 3 connectors care (fan, motor and hot end).

I grok it- Can you post a picture showing exactly where you’re touching it on the connector to get it to work? One of those pins may not be fully seated. Also, if the connection is loose, “getting it to work by touching it with the multimeter” can potentially damage components on the board. You’ll want to stop doing that for now.