Towing module now coded to car, blinkers don't blink fast anymore...
 

I'd mentioned earlier that my shop foreman asked if I'd "coded" my X5 after I'd installed the factory hitch and towing light control module. Well, he checked the coding today and the ECU hadn't yet recognized that the module was installed, even after towing over 750 miles. So he coded it to now recognize the module. Guess what? The blinkers don't flash faster with a trailer hooked up like they did before.

For others who've said that they also have the fast blinkers with their trailers, might want to have the coding checked.

Good info, thanks for posting it.

I had intermittent fast blinking, but only on some rental trailers. With a ground wire separate from the wiring harness, it went away. I wonder whether coding it changes the threshold for high current draw triggering a rapid blinker.

With the Uhaul trailer I had a few weeks ago, I ran a ground from the trailer directly to the hitch platform with no change. I'd also plugged in a trailer I bought last weekend (aluminum full deck race car trailer with disc brakes and led lights) and the lights flashed fast. Plugged in after getting the X5 back, and now flashes normally. And the trailer lights don't flash every 12 or 15 seconds like they did before.