Probably need to type a novel to get all the information to people who know more than me.

Moving to alsaka and was pulling my lady’s car on a uhaul carhauler. Never had an issue with my truck, until 60 miles into the 3200 mile trip.
started as sudden loss of speedometer and getting brake and and ABS lights. Before I could pull over things went back to normal. Happened a couple of times and then drove 500 miles perfectly fine. Happened again and stayed that way for an hour. Pulled over and cleaned and tightened battery terminals. Things were perfect for a couple hundred miles until crossing into Canada. Lost speedo again and got same lights. This time the problem became consistent. After two parts stores didn’t have a speed sensor, I layed in the freezing mud and cleaned the speed sensor. Fired up the truck and had no lights and my speedo worked. This lasted 20 miles. Problem came back. I drove to Calgary and 10 miles from the hotel also got a check engine light on. Cts2 showed “P0500” speed sensor.
Next morning I arranged for a new trailer from uhaul after finding corroded wires. I also left my truck and a highly recommended diesel performance shop. The truck didn’t have an issue that day and they could find no issues with it on three separate road tests.
Today ten miles out of Calgary I have the same issue. It stayed on for awhile and threw the same check engine code. Left the second trailer at a uhaul and after unhooking got my speedo back but still had lights. Got codes cleared by a different performance shop. Drove to Edmonton without issue and had the speed sensor replaced anyway. Nobody had the pig tail to replace that too.
Drive 20 more miles and for about a minute had the lost speedo and lights but it went away.
Now im about to hit the Alcan and leave civilization for 1500 miles not knowing what is causing this problem. The only option left is a dealership and thier ridiculous shop rates.

Did the trailer possibly cause a tipm issue?
Im no longer towing. We unloaded the car and will be driving separate. So a reflash could maybe work.

Could it not not be the sensor but be wiring? The performance shop couldn’t get me in but advised that just replacing the sensor isn’t enough. Do I shell out for yet another night in a hotel to wait for the wiring harness?

if the dealership won’t reflash the tipm, can I just drive without a speedometer? I’m afraid this could turn into loosing headlights or limp mode.

That’s my thought. Was the thought of the mechanic who couldn’t find anything in Calgary too.

Yep I’ve got my rpm and speeds down pretty solid. Plus have the car we are no longer towing to follow. So as long as nothing else is going to arrise I can definitely drive without a speedometer. Hopefully when the abs light is on my antilock brakes are working. But I’ve also driven plenty of miles on bad roads without abs in older vehicles if that is the case

Found the issue to be loose connections on the abs module. Tightening everything up fixed the issue and no issues thus far.
Probably wasn’t worth the frostbite on one toe and it could have waited. Peace of mind driving the Alcan though......