Tranny not shifting right.
Feels like its slipping, not finding the right gear, loss of power, etc.

I have an OBD2 reader and got p0700. Generic tranny code.
Not sure what to do next. How do I read a more detailed code?

I've read about 20 threads on this.
Many say speed sensors, and many others say it's not sensors.
Most threads are unsolved.

 

Assuming you have a fancy DRB code reader, where do you plug it in?
Same OBD2 port?

 

Same port. Make sure your scan tool is compatible with the TCU, not all scanners can read the TCU, but will show a generic code only.

Copied and pasted this from random website (yourmechanic.com)

P0700 code definition

P0700 is a generic OBD-II code that is indicating a fault within the transmission control system. This code may be seen with shift solenoid codes or other transmission codes.

What the P0700 code means

P0700 is set when the PCM detects a malfunction in the transmission control system. This malfunction causes the vehicle to set a Check Engine Light and trigger a failsafe mode. Once the failsafe mode is set it will remain until the fault is repaired or normal operation is detected.

What causes the P0700 code?

Faulty transmission control module
Transmission valve body fault
Shift solenoid issues
Open or short in the wiring harness
What are the symptoms of the P0700 code?

Check Engine Light displayed on the dashboard
Poor gas mileage
Transmission shifting problems
Engine stalling, running poorly, or dying
How does a mechanic diagnose the P0700 code?

A mechanic will begin by hooking up a scan tool to the vehicle and checking for all codes present. If P0700 is found, it is generally not alone.

Check all the freeze frame data for all codes to see under what circumstances the Check Engine Light was set.

Next, the technician will clear the code and take the vehicle for a road test to duplicate the concern.

Once this is performed, a visual inspection will be performed of the transmission and all wiring harnesses of the transmission.

Lastly, the scan tool will be used to monitor transmission information while driving, such as solenoid operation and the condition of the valve body.

Common mistakes when diagnosing the P0700 code

Mistakes are made when all steps are not followed or are not completed at all. Though a car may have a typical repair that fixes the P0700 code, this may not be true in all circumstances, which is why diagnosis is performed step-by-step.

How serious is the P0700 code?

P0700 can potentially indicate larger issues with the transmission or the future of the transmission. Some serious drivability problems can come along with this code and care should be taken.

The vehicle should not be driven if it is having trouble changing gears or it is stuck in one gear as this will cause further damage and is a safety hazard on the road.

What repairs can fix the P0700 code?

Transmission control module (TCM) replacement
Repairing or replacing faulty wiring
Valve body replacement
Transmission shift solenoid replacement
Additional comments for consideration regarding the P0700 code

P0700 is commonly seen with one or more shift solenoid codes. This may be as simple as low fluid due to a transmission leak, or a failure of the transmission on the extreme side of the spectrum.

When a transmission is failing, it is not uncommon to see metal flakes in in the fluid. These flakes clog shift solenoids and the valve bodies and can result in the P0700 code. When excessive metal buildup is found in the transmission, it is due to mechanical wear and can be an indication the transmission needs rebuilt or replaced.

 

Dont forget about the grounds when it comes to the wiring. One bad ground can cause all sorts of trouble. The XJ can be quite fussy.

 

I called my local mechanic and he had no idea what I was talking about.
I said I plugged a generic OBD2 reader and got general transmission fault.
I told him I need a "special" code reader to get the specific code.
He had no idea what I meant.

Do I need to go to the dealer?
It might look like this is the end of the line for the Barnacle.

 

How do I know if a scan tool is compatible with "TCU" ?

This yields nothing.
https://www.google.com/search?q=tcu+scan+tool

 

Snap-on scanners, including the MT2500 brick and all OTC scanners will work for your XJ. P0700 is stored as an info code for the ECM/PCM. The specific code from the TCM can be read with any of the scanners I mentioned above.

 

In this case the OTC scanner would be the one you want as the SO scanner will cost...unless you have the money to spend, then get the SO, quality unit.

If you have a laptop, you can purchase an OBD2 cable with OBDwiz for cheap on amazon, ebay, CL...I did this years ago. Think I paid around $40. When you connect to your laptop, it will ask what scanner port you want to use...there's 2, one for the PCM and one for the TCM. The PCM will be the one with more options, so choose the other. It will read and reset your TCM codes.

 

His TCM does not have a port. The only port in these Jeeps is the Data Link Connector.

 

Bimmer,


Make sure your trans fluid is full and it doesn't stink, and it's not black-ish.


Loosen your purse strings and take it to the dealer and have them check it out.

 

You misunderstand, it's the software in the program that splits it. Yes, the data port is the same.

 

Guess I could have worded that better...LOL

 

I second checking the fluid condition and level as well.

 

To make it a little more clear...

When you hook the data cable from your port to the PC and connect, it gives you 2 options to connect, one is the PCM, and one is the TCU. The PCM has more "channels" if you will...so to read the TCM, you connect to the other via the software. My bad for not being more clear.

 

I'm spoiled...hehe I have both