Titan owner: Anyone have a problem with your truck cutting out while shifting in tow mode, was pulling a 6000lb trailer. It made the check engine light come on.
Intelligent Tinkering: Lots of us first gen owners have had a problem with the transmission crapping out, overheating and fading out, usually when NOT in tow mode and/or not 3rd gear and when towing heavy loads for long distances at relatively high speeds. But not the engine. But this isn't much info. Was it just as you pressed the tow mode button? Is that what you mean by shifting? Or was it in tow mode already and shifting gear normally? Did it cut completely and shut down? Or cut momentarily and pick up again? Does it run now?
Titan owner: It's a 2017 5.6, just bought this truck. It has 72000 miles on it. Just hooked up to my trailer and took off in tow mode .I would say I was coming out of second gear and as the rpms were peaking to shift it started to flutter so I let up on the accelerator and then slowly tried it again and it shifted fine.Then it did the same thing. Still runs fine but it cause the check engine light to come on.
Intelligent Tinkering: Pull the codes. Then try clearing the codes and see if you can make it happen again in drive and then again in the next gear down so it hits that same rpm but doesn't shift. Run this test a few times to be on the safe side. You'd like to know for sure that it isn't just a simple misfire that happens at that same rpm. Two repeat occurrences under the same conditions is better than one for diagnosis but still not a slam dunk. Chances are still fair to middling that it's not connected to the upshift, and you'd like to know for sure. But if it is there's an explanation: on most electronically controlled transmissions the TCU does send a signal to the ECU to change the timing on gear shifting, and if the value the ECU gets is wrong you can get a misfire or loss of power. I'm not sure if this applies to the Titan, but since it does have a separate TCU this seems likely.
Later:
Titan owner: Just took the truck out and drove it with and without tow mode and it did just fine, but wasn't pulling a trailer. Will take it to the dealer and see what they say.
Intelligent Tinkering: I hope they manage to understand what you're trying to tell them -- a big "if" because you're talking to the "service associate," not a mechanic. Getting through to these desk-bound numpties is very hard sometimes because they are trained to discredit what the owner says. It's true the the average owner knows diddly squat and misreports symptoms and invents them in their muddled head, so we perhaps can't blame them for that. But the whole corporate "customer experience" interface bullshit makes life hard when you have a real engineering problem to report and solve, especially one that can't be replicated unless the tech goes for a test drive with a 6,000 lb trailer. But they will probably say that a couple hundred rpm drop is not unusual when upshifting with the heavy load. This is for the reason given earlier: TCU tells ECU to retard the timing momentarily on upshift. What is unusual is that it caused a misfire. We assume that's what it is, since you haven't pulled the codes. But that's the most likely explanation. (The P300 code series.) So make sure they hear that loud and clear. Good luck. (You'll need it.)
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