P0872 code & shift range inhibited

Aking · Mar 15, 2017

I need to figure out this code. My truck wont shift out of park. Goes into drive, then clicks then feels like its in neutral. Line blinks under D then says shift range inhibited. Changed nsbu and ignition switch. Neither one helped. What should i be looking for?

Aking · Mar 15, 2017

Im sorry. It does shift out of park, that was a typo. I also have R still available.

Rvn4me · Mar 15, 2017

Changed nsbu and ignition switch. Neither one helped.
Neither one will fix P0872

What is the history on the trans? What programmer. How hard do you drive it?
We need ALL the info or we can't help you.
P0872 is a stuck E shift valve. Not a good sign.
That is the middle valve in the upper half of the valve body.
Drop the pan and switch the E and D solenoids. They are the 2 center solenoids between the A&B trim and F trim. See if it changes codes. You may also have a bad internal harness.
Swapping the solenoids and the code follows it's a bad solenoid? If not then it's more likely debris in the bore?
Pull the pan and look for material in the pan. If you do your Trans has to come out.
Google (Duramax P0872) lots to read

Aking · Mar 16, 2017

Its just a stock trans. I just bought the truck last April and have had 0 trouble out of it as far as trans issues. I guy I bought it from used it on his farm. I rarely do any pulling, just hauling equipment in the bed. I messed up one night and drove it kind of hard spinning the tires and thats when I started getting the message.

Ok, so I dropped the pan and there was debris in the pan (small metal shavings). I didn't notice anything else unusual. The fluid did smell a little burnt.

Is it ok to put the pan back on and switch the E and D connectors and run the truck? I probably just drained about 5-6 quarts of fluid. I will need to run it to reset the codes and see if I can get the code to change.

Aking · Mar 15, 2017

I looked up P0872 and it calls for temperature pressure switch on the circuit c. How does this equate to the e solenoid?

Mike L. · Mar 15, 2017

When E shift solenoid is fired, it grounds the pressure switch so the TCM knows the command was completed. If the solenoid didn't fire, the TCM will give you range shift inhibited on your DIC.

Aking · Mar 16, 2017

Heres the pan.

Aking · Mar 16, 2017

Here's a few more. I can't say I saw anything too large in there. There was some small pieces but its really just looks more like dirt then metal. Let me know if anyone sees anything unusual.

Mike L. · Mar 16, 2017

You have serious problems there.

Aking · Mar 16, 2017

Yup, I have been talking to a guy locally about have my transmission rebuilt here soon.

Aking · Mar 17, 2017

This is why i posted photos. I dont get into trans much so not sure what to looks for.

testdrive · Mar 17, 2017

Some of that material is clutch friction material. Something caused your problem whether it was just a stuck valve or loss of a clutch pack. Regardless with that many miles a tear down and rebuild with new rubber and clutches is warranted. I read that you indicated that the fluid smelled burned, that means that it was overheated or very old.
Good luck and let us know how it turns out.

Aking · Mar 18, 2017

I pulled the valve body and opened it and checked the e valve. It doesnt seem to slide smoothly. I need to get a reamer tool and maybe even replace the e valve. What is a good kit to get that has everything i need for this?

Aking · Mar 19, 2017

Checking valves and found one severely stuck. Replacing them with new non stick valves and waiting on my reamer tool. Which valve is this by the way? This is the one that was tough to get out but i am replacing them all.

Mike L. · Mar 19, 2017

No such thing as a non stick valve.

davester · Mar 19, 2017

It was sprayed with PAM(tm) at the factory!

Aking · Mar 19, 2017

Well new replacement c,d, and e valves i should say.

Aking · Mar 19, 2017

I did notice a little flashing and burrs in one of the bore holes so the reamer tool should help take care of that. I noticed it get stuck towards the back of the valve passage. Once it get past one particular point in the back, it slides right out when you tip the vb on its side.

IGO1320 · Mar 20, 2017

Allison transmissions are very clean, anything in the pan is a serious problem. Just have it rebuilt.

Aking · Mar 20, 2017

First i am doing some investigating on my own. The valvebody looked really good on the inside. Going to ream out the bores and replaced the C D and E valves. New internal filter and fluid.

P0872 code & shift range inhibited

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