When I have a trailer wired to my truck (2000 F250 Powerstroke, manual transmission) the engine dies when I apply the brakes. I have a Reese brake controller, and if I set the brake level to 2.5 or below, the engine runs fine. If I set it to anything else, the engine dies when the level reaches about 3.0. It doesn't matter whether the trailer brakes are activated by the vehicle braking system or by the manual switch on the brake controller.
Sometimes the MIL (Service Engine Soon light) comes on, but there is no OBDII code in the computer. Turning the iginition off/on always clears the MIL. I've also had a few engine sputters, particularly in wet weather that turn on the MIL, but there's no code then, either, and the engine runs fine after the sputter. Both problems (braking, random stalls) started around the same time.
I replaced the whole back end of the wiring harness, along with the connector sockets, as it showed some wear, but that didn't change things.
As it's a holliday weekend, I can't get a replacement controller, which is my next suspect, but in the meantime I was hoping someone had seen something similar and could help solve the mystery.
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Resolved - It looks like it was the brake controller. Likely when there was enough current going to the trailer brakes the ground was floating enough to mess up something in the engine sensors, etc. I've made several runs with the new contoller, a Tekonsha Prodigy, and there have been no more stalls on braking.