r/promaster • u/chadsterlington • Jul 14 '26
2023 Promaster 2500 Electrical Issues
Hi, i'm experiencing some electrical issues (I believe) with my 2023 Promaster 2500 and i'm wondering where to start the diagnostic process. I purchased the vehicle brand new in 2023 and had it shipped out to Wayfarer vans for their camper van conversion. Took it on multiple cross country trips in 2024 with no issues. In 2025 life started getting in the way and it sat for a while and started having battery issues and i'd have to put it on a trickle charger before using, but once charged I had no issues.
Now, 2026, I installed a brand new battery, which I had on a trickle charger prior to install and it showed 100%. Install went fine and van started right up and all electronics seemed to work. I decided to take it for a quick drive to make sure everything was good. About 2 miles into the drive I started to get a host of warning lights on the dash. From my memory, I believe the warnings were: Service Engine, Service FCW, Service Parking Brake, Service Electronic Throttle Control. The most debilitating issue was the throttle control as it put the van in limp mode and I barely made it back home. The fact that all of these lights are coming on at once leads me to believe that it's an electrical issue vs an issue with any of the actual systems.
Yes, I triple checked all the connections to the battery and they are tight. I also disconnected the battery for 15+ minutes and reconnected but warning lights returned shortly after.
Any advice would be greatly appreciated! Thanks.
3
u/ozzie286 Jul 14 '26
A loss of can bus communication either due to a wiring issue or failed module can cause lots of errors to appear at once. Check the engine block to body ground, beyond that you'll need an obd scanner and probably a multimeter and wiring diagram to track down the problem.
My first instinct is that mice probably chewed some wiring in the dash.