P0893 Multiple Gears Engaged
OBD-II Trouble Code Technical Description
ASE Certified Technician
总裁俱乐部appMultiple Gears Engaged
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Mercedes Benz, Toyota, Kia, Mitsubishi, Jeep, Chevrolet, Dodge, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
If your vehicle has stored a code P0893, it means that the powertrain control module (PCM) has received a data input signal which indicates multiple gears in the automatic transmission have been engaged simultaneously.
The transmission control module (TCM) may be a stand alone unit but is most commonly integrated into a single housing with the engine control module (ECM). This is called the PCM.
总裁俱乐部appThe PCM utilizes input signals from multiple engine and transmission sensors to calculate automatic transmission shift strategy. Electronic shift solenoids are used to interrupt the flow of high pressure fluid so that the transmission may shift gears. If multiple solenoids are activated simultaneously, multiple gears will be engaged and the desired gear ratio will be impossible to achieve.
As with many other automatic transmission malfunctions, multiple gear engagement may also be caused by mechanical failure. Often when the friction material on one or more clutch discs is compromised, the hot material effectively 'welds' multiple sprags together and creates a multiple gear engagement condition. This condition is accompanied by the distinctive odor of burnt friction material in the fluid.
If the PCM detects that multiple gears of the automatic transmission are engaged simultaneously, a code P0893 may be stored and a malfunction indicator lamp (MIL) illuminated.
What is the severity of this DTC?
总裁俱乐部appA stored code P0893 indicates that either a serious electrical issue or a catastrophic mechanical failure has occurred. Conditions which contributed to a code of this nature being stored should be rectified as quickly as possible.
What are some of the symptoms of the code?
Symptoms of a P0893 trouble code may include:
- Transmission slippage
- Delayed and/or harsh gear engagement
- Erratic transmission shift patterns
- Strong odor of burnt friction material in transmission fluid
What are some of the common causes of the code?
Causes for this code may include:
- Catastrophic internal (mechanical) transmission failure
- Shorted wiring for shift solenoids
- Defective shift solenoid/s
- Faulty PCM or a programming error
What are some P0893 troubleshooting steps?
When diagnosing automatic transmission codes, you should begin by making sure that the transmission fluid is clean and that the transmission if filled to the appropriate level. If the fluid level is low, locate the source of the leak and repair the condition. Refill the transmission with the recommended fluid and proceed.
If the fluid is excessively dark and smells strongly of burnt friction material, it will need to be replaced. This can be accomplished by removing the transmission pan (and draining the torque converter) or flushing the transmission (recommended). Either way, you will want to replace the filter at this time too. When removing the pan from the transmission, take care to preserve whatever debris may have landed therein. If the pan is relatively clear of debris you can assume that the clutches are mechanically intact. If there is an excessive amount of friction material in the pan (and stuck to the magnet), the transmission will require a rebuild from a qualified technician.
A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle specific diagnostic information will be required to diagnose a code P0893.
If you can use your source of vehicle information to locate a technical service bulletin (TSB) that matches the vehicle year, make, and model; as well as the engine size, code/s stored, and symptoms exhibited, it could yield helpful diagnostic information.
总裁俱乐部appWith the transmission filled to the appropriate level with the recommended fluid, proceed with the first step of the diagnosis.
Use the scanner (connected to the vehicle diagnostic connector) to retrieve all stored codes and pertinent freeze frame data. It is a good idea to write this information down before clearing the codes then test-drive the vehicle until the PCM either enters readiness mode or the code is reset.
If the PCM enters readiness mode at this time, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions which contributed to the code being stored may need to worsen before an accurate diagnosis can be made.
总裁俱乐部appIf the code is immediately reset, the next step of your diagnosis will require that you search your vehicle information source for diagnostic flow-charts, connector pin-out charts, connector face views, and component testing procedures/specifications.
Use the DVOM to test voltage at the shift solenoids (key on and engine off). Shift solenoid circuits typically consist of a constant supply of voltage and a ground supplied by the PCM at the appropriate time to realize the desired gear ratio.
- Most multiple gear engagement codes are caused by catastrophic mechanical transmission failure
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