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P0700: Transmission Control System Malfunction

The OBD-II scanner error code P0700 problem is a generic code that applies to vehicles equipped with OBD-II. It refers to the transmission control module (TCM) in the automatic transmission. The P0700 code is informational. The code points to a general fault, not a direct fault. To correctly identify the problem, you will need to have a scan tool that communicates with the TCM to determine the problem in the transmission.

When the P0700 code is present, the malfunction indicator lamp (MIL) may be illuminated. You may be seeing poor gas mileage or have transmission shifting problems. The engine could stall or run poorly. When hooked up to the scan tools, there will most likely be other codes present because the P0700 code is generally not alone. Diagnosing the specific problem for a particular model will rely on tracing through the possibilities.

What Causes P0700?

What does the code P0700 mean? It is often seen with shift solenoid issues or other transmission codes. The most likely reason the code appears is that the TCM detects a problem in the transmission.

  • A faulty TCM
  • Shorts in the wiring
  • Transmission issues
  • Defective shift solenoids
  • Defective engine coolant sensor
  • Dirty transmission fluid or low levels

Potential Resolutions for P0700

The P0700 code indicates a problem with the transmission. It should not be ignored, because there can be serious drivability problems now and in the future. The technician should check for all codes present to accurately diagnose the problem. Possible resolutions include:

  • TCM replacement
  • Replacing faulty wiring
  • Valve body replacement
  • Shift solenoid repair or replacement
  • Replace transmission fluid

The P0700 code can also be seen if the fluid is low or the transmission is failing. If the TCM does not communicate with a TCM compatible scan tool, the TCM may be faulty and need to be replaced. However, it is rare that the TCM is faulty. It’s most likely something within the transmission or electrical system.

Additional Comments on P0700

How do I fix trouble code P0700? When you’re diagnosing P0700, you’ll need to look at the freeze frame data to see what occurred when the check engine light was set. It could be a slipping converter clutch that is causing the code. Monitor the Slip Speed, Lockup Duty Cycle and Output Shaft Speed for irregularities.

One thing to try when fixing the P0700 code is to clear the code and take it on a road test. Before clearing out the data, record all present codes and any data from the scan tests. After the second road test, look for the codes that appear. If the codes don’t return, it could have been a glitch, just an odd sensor reading or sticky solenoid. If the codes do return, you should inspect the transmission with the oil pan removed.

A failing transmission can cause the P0700 code. Mechanical wear causes excessive metal buildup in the transmission, which means that the transmission needs to be rebuilt or replaced. Metal flakes in the transmission fluid can also result in a P0700 code. Flakes appear when the transmission is failing and get clogged in the shift solenoids.

The P0700 is often underdiagnosed, by assuming that if the code doesn’t come back it is repaired. However, it can also be over-diagnosed when extensive repairs are recommended before determining what is really at fault. Look for all the codes and data associated with the P0700 code before making expensive repairs. Sometimes, it is the transmission fluid level or a wire that needs to be replaced. Of course, it could also be that the transmission is failing and needs to be repaired.

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