Got a question for you heavyd. I got a 2016 Lonestar and got the dump switch flashing. Got the following code, spn-1756 fmi 5. I replaced both solenoids but still have the flashing like and same code. Airbags stay inflated but won’t dump.
You have a wiring problem between the body controller and solenoid pack. Some times the board the solenoids plug into become corroded internally and are bad. At the connector, one pin is main ground, (white) and the other four are for each solenoid. Normal running, the A solenoid is energized, B is de-energized. Dump the B solenoid is energized and A is de-energized.