. I'm wondering if you have fixed this issue. I have the same or similar problems. Usually the security light will stay on when I start it and always the truck will still be hot like after I fuel up or stop for groceries. It will go into gear hard, has no power and after a few seconds the check engine light always comes on. Sometimes I'll just keep driving it and after a while the engine light goes out and after I start the truck the next time it will be fine. Other times I clear the code and it will be fine for a while. Something I have noticed on a few occasions is that the radio will be reset when the truck malfunctions. For example when I turn it off I'll have it on Sirius Xm and when I restart it the radio will be on FM static. It almost seems like it completely loses power. I've been wondering if it could be a key switch issue. Anyway hoping to stumble across someone who has solved this problem.

 

Have you done the basics like doing a load test on the battery? Voltage drop tests on the battery terminals, cables and ground lugs? There should be less than .2v drop on any of those connections. Anything less than 12.4v(75% charged) resting voltage will cause problems. My experience is these trucks are very sensitive to voltage due to the canbus system. Start with the basics. I wouldn't be a bit surprised if all those crazy things going on is due to that one cause.

 

Hello thanks for responding. I hadn't really checked the battery itself although I cleaned the cables, grounds etc. When I turned the truck off I checked the voltage and it showed 12.6 volts. So I turned the lights on for about a minute. And the voltage dropped to 12.1 and stayed that way I'm assuming if I start the truck with any kind of load on the battery it would show too low. Does this sound normal or should I take it and get it tested?

 

Wouldn't hurt to have it checked. Old saying of "GIGO" always applies. "Garbage In, Garbage Out". Meaning if your electrical system isn't 100% where it starts (the battery) it can lead to all sorts of random issues.

Mainly look it over for the battery connections, ensure they are snug and clean. Most auto parts stores will do a free check of your battery/starter/alternator.

With the truck running you should see anywhere from about 14-14.6 volts. (I've seen them also at 13.5 while running for a while under no-load. IMO anything above 13.5 is reasonable)

Rapid test with a multi meter would be to start the truck and have the meter across the terminals. Turn on all the lights/accessories and rev the engine to about 2,000 RPM. It should hold over 13.5-14.6 volts nominal. (Ideally slightly over 14vdc) If you run this test and see the voltage drop below 12.5. then I'd start looking at connections and alternator condition. (You'll know really quick if the belt is slipping.)

The voltage you've noted while 'off' is nominal. About 12.5 is fine IMO. (If checked after just shutting it off you can expect it to be slightly higher, as the surface charge will make it a whisker higher). Turning the lights 'on' and having it drop and hold at 12.1? That's expected as you've now wiped off the surface charge and are now draining the battery. It's not quite 100% however as a test. The more advance test gear the shops and parts houses use are more accurate.

S-

 

I replaced both sensors on the driver side of the transmission, stopped it from going into limp mode. When hot outside the trans temp light would come on and put the trans into over temp shift mode, fixed that by putting in a new TCM. The temp light never came on in the winter months, so it was a heat issue at the computer. It's definitely a power issue to the transmission through the computer.. There's a video on YouTube now that's been up for the last few months that shows the problem with the over temp light and transmission going into limp mode. I think it's under BL Automotive's channel...

 

Been turning my key on and off 3 times without starting it and then starting it the 4th time I turn it if it goes in limp mode . Seems to work 90 % of the time
sometimes I have to do it a couple times