2012 6.7 Powerstroke Acting Funny

[Togo444]

I towed my Voltage 3600 down to SoCal from Salt Lake City to enjoy the theme parks. While I was on my way down my 2012 6.7 Powerstroke F350 DRW did the strangest thing. I had the cruise set to 69mph and was heading down a hill. The truck downshifted to keep the speed down. It downshifted to 4th and then down shifted to 3rd! Normally it doesn't take it that far down at that speed but it did. The truck redlined then pow... "reduced engine power" displayed on screen, the wrench light came on and another message flashed up to "stop safely". I lost the accelerator and pulled over down the hill at a safe off ramp. The truck shut down, no brakes nothing, luckily the off ramp went up hill. I got out popped the hood and there was nothing wrong. No leaks, oil smells. I was freaked out, nothing like that happened to me before. I restarted the engine. Fired back up with a check engine light. I decided I was going to pull the battery cables and reset the computer codes so I shut it down again. It was raining hard and then I thought I can do that farther down the road so I started it up again. No check engine light, no wrench light nothing. The truck worked perfectly fine. Not a hiccup the rest of the trip. Any body have this happen to them before? Any explanation other than the engine going into safe mode?

[Occupant5143]

This might be a good question to ask on one of the Ford Super Duty forums.

[ATCguy]

Originally Posted by Togo444

... Any body have this happen to them before? Any explanation other than the engine going into safe mode?

Nope... did exactly what it's programming designed it to do.

One note: they don't recommended that you use cruise control while towing. That said, like you I use it too... but I've never had it downshift to 3rd. It already damn near red lines in 4th sometimes, and a quick tap on the brakes occasionally to keep the speed in check is usually all it takes.

[Tanman]

I think you over revved your motor. It sounds like a fail-safe to keep from blowing up the engine. My diesel will sometimes do the same but I tend to control it by disengaging the tow on the shifter or use the trailer brakes to slightly slow somewhat. The big Voltage will really rev the motor up going downhill.

[Togo444]

That is what I thought. Too many revs. I will keep the speed down going down hill next time. I usually do but this time I didn't. Thanks for the replies and I will goose the trailer brakes to keep from the down shifts in tow haul mode.

[azdryheat]

Never use cruise control on a wet road.

[dsol]

Did you say the engine just shut down or that you shut it down? If it shut down on its own that is really dangerous and you should take it in. The code for the check engine should still be present even if you unplugged the battery cables so hopefully a scan tool will show what happened. Limp mode is one thing and reducing power is fine but the engine shutting down could be really dangerous--like as bad as possible.

I had an older truck and I never went anywhere without a scan tool that you can pick up for like $100 at Pep Boys or Harbor Freight. The check engine light could be a really benign emissions issue or it could be major but I would strongly recommend against trying to reset it until you know what it is. The scan tool will solve that problem.

While using cruise control while towing downhill in the rain might not be the safest route it should not result in 2 downshifts and an over rev. If it was that dangerous the tow/haul mode would lock out cruise control.

I also agree with the post that said you should check the super duty or power stroke forums. You will learn really quickly if this is a known issue or a fluke and what people have done to resolve.

Good luck.


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