Transmission not shifting properly?

2009 DODGE GRAND CARAVAN

135,000 MILES • 3.6L • 6 CYL • 2WD • AUTOMATIC

SUNNI420

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So, my van just started recently having this issue that I'm contacting you about. The van sometimes doesn't shift gears at all, which I think it's stuck in first gear. Then other times it will shift Into and through all of the gears that is until I stop at a stop sign/red light, once stopped it will then kick out of gear. I've also seemed to be able to trick my van if it's not shifting by being stopped at a red light, I'll turn the van off completely let it sit for a few and turn it back on before the light turns green and it will start shifting again.
Also, another thing I tried recently was unplugging the battery to let it sit unplugged for however long when I'm running errands or something and plug it back in when I'm done and that sometimes fixes it putting it in gear and shifting again.
I'm not sure what's going on or what it could be, I've been asking and looking everywhere to find no answers yet.
My guesses were anywhere from the transmission, to the shifter solenoid, and possibly even the ECM.
But again, I can't seem to figure it out.
Hopefully you will know and be able to help, that would be the best thing ever.
When you can, please let me know.
Thank you so much and I'm looking forward to hearing back from you soon, again thank you.

Oct 27, 2022 at 5:57 PM

CARADIODOC

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34,306 POSTS

What you're describing is "limp mode". That's where it goes into or stays in second gear, allowing you to drive slowly to a repair shop without needing a tow truck. The way you get it out of limp mode is as you're doing, by turning the ignition switch off, then restarting the engine. It won't come out of limp mode when the engine is running.

What you don't want to do is disconnect the battery. That is not resetting anything. What it is doing is erasing any diagnostic fault codes. You don't want to lose that valuable information. It also erases the learned data that affects shift quality. Some of what it learns over time has to do with making up for the normal physical wear that takes place at higher mileages. By erasing the learned data, the computer starts out again at the factory-programed default values for a new transmission. Those shift schedules can aggravate what is already happening and make it go into limp mode much easier. It can take as much as two miles and a dozen up-shift cycles to get back to the learned values it needs to be at.

The place to start is by having those fault codes read and recorded. The people at many auto parts stores will do that for you for free, but there's two things to be aware of. The first is often they use simple code readers that can only access the Engine Computer. Typically, in this situation it will have code P700 which just means there are fault codes that need to be read in the Transmission Computer. If they can't access that computer with their code reader, you'll need to find a mechanic with a scanner to have them read.

Once you know the code numbers, you can go here:

https://www.2carpros.com/trouble_codes/obd2/p1700

to see the definitions, or I can interpret them for you.

The second thing to be aware of is the people at auto parts stores are in the business of selling parts, not diagnosing problems. No diagnostic fault code ever says to replace a part or that one is bad. They only indicate the circuit or system that needs further diagnosis. When a part is referenced in a fault code, it is only the cause of that code about half of the time. First, we have to rule out wiring and connector terminal problems, or mechanical problems associated with that part.

Let me know what those fault code numbers are, then we'll figure out where to go next.

Oct 27, 2022 at 8:26 PM