2013 JKU with P2784 won't go into gear

Chicagojim23

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Dec 9, 2019
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5
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Denver
I've got a 2013 JKU 10A Rubicon I'm currently out of town and let a family member use my Jeep, I got a call from them saying the car won't go into gear and then got an alert of the P2784 from my GPS Tracker. At first it would go into reverse but not drive after having it towed they were no longer able to put it in reverse either . Basically it was like it was in neutral , no signs of anything wrong with it before then . Drove and shifted fine , she just drove it to and from the airport so no off road driving . Not being able to diagnosis it and being 2k miles away on vacation is killing me thinking about a possible transmission failure at 80k miles

Has anyone got the P2784 Input/Turbine Speed Sensor "A"/"B" Correlation and similar symptoms ? if so what was the fix ?

Thanks in advance for any input .
 
What causes the P2784 code?
The incorrect turbine speed code may have several causes:
  • Incorrect or unusual input speed signals are most often caused by defective turbine speed sensors (either input or output)
  • corroding or damaged wiring
  • defective shift solenoids
  • defective engine temperature sensors
  • dirty, mixed, or otherwise incorrect transmission fluid
  • failure with the PCM is a much rarer cause

What are the symptoms of the P2784 code?
The most common symptoms of the P2784 code include issues with or failure of shifting, poorly operating speedometers, and engine stalling upon breaking or bringing the vehicle to a full stop. Less common symptoms of this code also include decreased fuel economy, misfiring of the engine, and occasionally an illuminated Check Engine Light.

How does a mechanic diagnose the P2784 code?
A P2784 code can be diagnosed by a qualified mechanic technician using a code reader, such as a OBD-II scanner. Before checking the vehicle’s turbine speed sensor, a mechanic should first identify any damaged or corroded wiring in the engine bay and replace before further investigation.

A mechanic should then locate the speed sensor, which can be found either in the transmission housing or mounted to the housing exterior depending on the vehicle’s make and model, and check for any visible damage. Then, all OBD-II codes should be cleared and a test drive should be performed, after which a qualified mechanic will check to see if the P2784 code reappeared.

Common mistakes when diagnosing the P2784 code
Properly diagnosing the P2784 code can be difficult. Symptoms of the P2784 code are often mistaken for…
  • Full vehicle speed malfunction
  • Transmission malfunction
  • Driveline malfunction
  • Engine misfire
These misdiagnoses have been reported to lead to unnecessary turbine speed sensor replacement.

How serious is the P2784 code?
If the symptoms of the P2784 code in the vehicle include engine stalling or shifting malfunctions, the vehicle is potentially not safe to drive and therefore should be diagnosed by a qualified mechanic as soon as possible. Since symptoms of this code also include a decrease in fuel economy, it’s best to have the vehicle looked at by a technician as soon as possible regardless of the noticeable symptoms.

What repairs can fix the P2784 code?
Once the vehicle is examined and diagnosed by a qualified mechanic, replacement parts for your vehicle may be necessary. The most common potential repairs to fix the P2784 engine trouble code include:
  • Wiring replacement
  • Turbine speed sensor replacement
  • Turbine speed sensor connector replacement


I don't think you need to worry about replacing your entire transmission, I highly doubt that's the issue. In my opinion, I'd look at replacing the turbine speed sensor. Make 100% certain to use an OE factory Mopar part, I can't stress this enough!
 
Make 100% certain to use an OE factory Mopar part, I can't stress this enough!

I think someone else on this forum had a similar issue and used a aftermarket sensor. Even though it was brand new, they still had the code as the part wasn't in manufactured specs.

Spend the extra couple of bucks. Its not worth buying twice.
 
I think someone else on this forum had a similar issue and used a aftermarket sensor. Even though it was brand new, they still had the code as the part wasn't in manufactured specs.

Spend the extra couple of bucks. Its not worth buying twice.

Yes, this is a known issue with Mopar vehicles, and a lot of other non-Mopar vehicles as well. Always use OE replacement sensors for any vehicle you buy. The ones at the auto stores are cheap, Chinese junk.
 
So the dealership i took it to said the transmission is toast. I find it odd since it drove perfectly fine, clean shifts, no sounds nothing that would indicate a transmission going out. My mom was the one driving it and she stated that it was driving fine until a CEL came on and she pulled over to call me the when she went to drive off it wouldn't go into gear.

I was all set to just order a transmission (not having a dealer do this work) but gonna hold off till I get back to town and can look at it myself and take it to an indy shop

Anyone reccomend a good shop in Denver?

Screenshot_20191209-183029_Gallery.jpg
 
So the dealership i took it to said the transmission is toast. I find it odd since it drove perfectly fine, clean shifts, no sounds nothing that would indicate a transmission going out. My mom was the one driving it and she stated that it was driving fine until a CEL came on and she pulled over to call me the when she went to drive off it wouldn't go into gear.

I was all set to just order a transmission (not having a dealer do this work) but gonna hold off till I get back to town and can look at it myself and take it to an indy shop

Anyone reccomend a good shop in Denver?

View attachment 113903

I bet this was some fresh kid in their service department. Just because there is metallic content in the trans fluid doesn't mean the whole trans needs to be replaced. *eyeroll* Glad you are getting a second opinion.
 
I had that (lost the reverse) in Illinois from my jeep buddy at one time, he said there was a gear sound before it happened. It was a trans. relay.
 
I forgot to update this, I picked up the Jeep from the dealer and took it home. Ordered a Transmission Speed Sensor Module Plate, filter and fluid and a friend and I took a coiple hours swaped everything over and the cars been driving perfectly since. We've driven it a lot also probably 1500 miles of mountain winter driving and it's been driving perfect. The fluid was pretty gnarly so I'm going to do a drain, fill and filter at the next oil change and then every 10k for the next 30k miles just to be safe.

I paid the dealer $199 to do the diagnosis and they told me they were going to drop the pan to inspect the transmission but after looking at it I'm 99% sure all they did was look at the fluid on the dip stick (maybe pulled some with an extractor) and pulled the codes and sent me the $6300 estimate for a new transmission and transmission cooler. Crooks

Picture was the failed unit, got a dorman unit from autozone with some coupons it was only $220. Same Mercedes Benz stamps and parts numbers as the one I pulled so I think the doorman unit is oem. The dealers I called all quoted me around $700 for the part

20191214_103459.jpg
 
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Wow... screw that dealership. This is why I'm always so worried about who works on my vehicles. You have to find a shop you can trust with reputable mechanics, and rarely is that ever the dealership. My experience with the dealership is similar to yours. They won't bother taking the time to actually diagnose something thoroughly. Instead they'll just tell you that ________ is bad, and that it will cost ________ to replace it.

So have you had a chance to install the new unit and verify that it fixed the problem?

Also, that's good info about the Dorman unit. I wouldn't be surprised if Dorman is an OEM supplier to FCA.
 
Wow... screw that dealership. This is why I'm always so worried about who works on my vehicles. You have to find a shop you can trust with reputable mechanics, and rarely is that ever the dealership. My experience with the dealership is similar to yours. They won't bother taking the time to actually diagnose something thoroughly. Instead they'll just tell you that ________ is bad, and that it will cost ________ to replace it.

So have you had a chance to install the new unit and verify that it fixed the problem?

Also, that's good info about the Dorman unit. I wouldn't be surprised if Dorman is an OEM supplier to FCA.


Yep driven it about 1500 miles over the the 2 weeks or so since I replaced it. The dorman one had MB stamps and the exact same part number
I usually never go to dealers this happened while I was out of town and letting someone borrow the car. I just told them to bring it to the jeep dealer for an estimate.
I do 90% of my own work and diagnosis. Well I should rephrase the diagnosis lol I Google and join groups and find people who have experienced the same and try out their diagnosis. I can't diagnosis anything lol and my fixing things is walking through DIY youtube videos lol but hey it works
 
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Yep driven it about 1500 miles over the the 2 weeks or so since I replaced it. The dorman one had MB stamps and the exact same part number
I usually never go to dealers this happened while I was out of town and letting someone borrow the car. I just told them to bring it to the jeep dealer for an estimate.
I do 90% of my own work and diagnosis. Well I should rephrase the diagnosis lol I Google and join groups and find people who have experienced the same and try out their diagnosis. I can't diagnosis anything lol and my fixing things is walking through DIY youtube videos lol but hey it works

Good for you, that's awesome! I try and do most of the stuff myself, the only thing I'm hesitant to mess with myself is re-gearing and rebuilding an automatic transmission. Those are two things I don't want to try to "learn", just because I'm sure I'd mess them up the first time.

Glad to hear it was cheaper than a brand new transmission! Those guys are ripping you off on that price anyways. You can probably find a rebuilt transmission for around $2500 at most, plus labor to install it... I don't see $6300 there, that's for sure.