Three weeks ago my truck went into limp mode with no warning. Dealership installed a new transmission ($5200.) A week later the same thing happened so they replaced the ECM (at their expense). A few days after that...same thing again. They tried another new ECM. It stayed in limp. The mechanic says he traced down all the wires with no luck. He's about to throw up his hands. I haul cars with it so I'm hoping someone out there can offer some suggestions. Thanks

 

It turns out that it was a wiring issue. They replaced the wiring harness for the tranny. No problems after 3 days and about 500 mi so maybe they fixed it this time. So I have a new transmission I didn't really need now. I guess that isn't too terrible since it had over 350k on it. It had to go sometime. And maybe I ruined it by driving it 50 or 60 mi in limp mode when it first went out. With a 5k lb trailer.

 

Wait, did you pay for the trans or did they?