--- title: My Velit Heater Thermostat Controller is Dark or Won't Light Up description: thermostat controller dark no power at thermostat controller on heater --- [Skip to content](https://help.velitcamping.com/help-articles/my-velit-heater-thermostat-controller-is-dark-or-wont-light-up#main-content) ![Velit](https://help.velitcamping.com/hs-fs/hubfs/460684741_1701809850568731_4111707878241104706_n.jpg?width=150&height=150&name=460684741_1701809850568731_4111707878241104706_n.jpg) - [SHOP](https://velitcamping.com/) - [CONTACT US](https://velitcamping.com/pages/contact) - [HELP CENTER](https://help.velitcamping.com/help-articles) - SUBMIT TICKET Show submenu for SUBMIT TICKET - [Heater Support Ticket](https://velitcamping.com/pages/heater-tech-support-request) - [AC Support Ticket](https://velitcamping.com/pages/ac-tech-support-request) Open main navigation Close main navigation - [SHOP](https://velitcamping.com/) - [CONTACT US](https://velitcamping.com/pages/contact) - [HELP CENTER](https://help.velitcamping.com/help-articles) - SUBMIT TICKET Show submenu for SUBMIT TICKET - [Heater Support Ticket](https://velitcamping.com/pages/heater-tech-support-request) - [AC Support Ticket](https://velitcamping.com/pages/ac-tech-support-request) - [Back to Velit Website](https://velitcamping.com/) [Back to Velit Website](https://velitcamping.com/?hsLang=en) How can we help you? - There are no suggestions because the search field is empty. 1. [Velit Customer Support](https://help.velitcamping.com/help-articles?hsLang=en) 2. [Troubleshooting](https://help.velitcamping.com/help-articles/troubleshooting?hsLang=en) 3. [Heater Troubleshooting](https://help.velitcamping.com/help-articles/troubleshooting?hsLang=en#heater-troubleshooting) May 14, 2026 # My Velit Heater Thermostat Controller is Dark or Won't Light Up ## T-stat controller on my Velit heater goes dark Always make sure you have unpluged the fuse/power to the heater for at least 15+ seconds as the first troubleshooting step. This resolves most unexpected behaviors with our heaters. A dark controller is almost always due to amperage drop over distance (wiring), not the controller going bad itself. We very rarely see thermostat controllers going bad as a part, although that can happen. You can easily check the 3 little wires that attach to the back of the thermostat board that they are soldered on and intact. The back plastic plate on the back of the controller just prys off. That would be obvious quick diagnosis.  #### The Deeper Places to Check Wiring: **Was the main power harness for the heater extended to reach the battery?** If our harness power wires are 14AWG, was a larger AWG such as 12 gauge or 10 gauge used for the extension wire? This is the most common reason for electrical issues with out heater - amperage loss over distance. **If the power wire is extended from our harness the wire must be upsized accordingly for the distance.**  **The 8-pin (7 wire) connector going into ECU inside heater.** Unplug that big black connector from the ecu and inspect the female connector pins for evidence of spark or intermitten contact signs. [This video shows how to inspect that connector.](https://help.velitcamping.com/help-articles/check-harness-ecu-for-electrical-issues?hsLang=en) A **multimeter tool** would be useful to determine how much power is making it where if the screen is dark on the controller. You could provide this information to our support engineers. ### Once you have checked these items use the link on this page to [submit a heater support ticket](https://velitcamping.com/pages/heater-tech-support-request?hsLang=en) abd provide the information required in the form, and a tech will follow up with you. - [Troubleshooting](https://help.velitcamping.com/help-articles/troubleshooting?hsLang=en#main-content) - [Heater Troubleshooting](https://help.velitcamping.com/help-articles/troubleshooting?hsLang=en#heater-troubleshooting) - [A/C Troubleshooting](https://help.velitcamping.com/help-articles/troubleshooting?hsLang=en#a-c-troubleshooting) - [Product Manuals](https://help.velitcamping.com/help-articles/product-manuals?hsLang=en#main-content) - [Velit Air Heater Manuals](https://help.velitcamping.com/help-articles/product-manuals?hsLang=en#velit-air-heater-manuals) - [Velit Air Conditioner Manuals](https://help.velitcamping.com/help-articles/product-manuals?hsLang=en#velit-air-conditioner-manuals) - [FAQs](https://help.velitcamping.com/help-articles/faqs?hsLang=en#main-content) - [Velit Air Conditioner FAQs](https://help.velitcamping.com/help-articles/faqs?hsLang=en#velit-air-conditioner-faqs) - [Velit Air Heater FAQs](https://help.velitcamping.com/help-articles/faqs?hsLang=en#velit-air-heater-faqs) - [Comvolt Power Station FAQ](https://help.velitcamping.com/help-articles/faqs?hsLang=en#comvolt-power-station-faq) - [General](https://help.velitcamping.com/help-articles/general?hsLang=en) - [Shipping & Fulfillment](https://help.velitcamping.com/help-articles/shipping-fulfillment?hsLang=en) - [Product Questions](https://help.velitcamping.com/help-articles/product-questions?hsLang=en#main-content) - [Velit Air Heater Product Questions](https://help.velitcamping.com/help-articles/product-questions?hsLang=en#velit-air-heater-product-questions) - [Velit Air Conditioner Product Questions](https://help.velitcamping.com/help-articles/product-questions?hsLang=en#velit-air-conditioner-product-questions) [![Velit](https://help.velitcamping.com/hs-fs/hubfs/460684741_1701809850568731_4111707878241104706_n.jpg?width=150&height=150&name=460684741_1701809850568731_4111707878241104706_n.jpg "Velit")](https://velitcamping.com?hsLang=en) Copyright © 2026,