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Error Code P0893 is defined as Multiple Gears Engaged. This is a generic trouble code, meaning it applies to all vehicles with the OBD-II system, especially those made since 1996 up to the present. This includes vehicles from, but not limited to, Chevrolet, Dodge, Kia, Jeep, Mercedes Benz, and Toyota. Specifications on the definition, diagnostics, and repairs may vary from one make, year, model, and power configuration to another.
If the vehicle stores Error Code P0893, that means the PCM (powertrain control module) has determined a data input signal that suggests multiple gears’ engagement in the automatic transmission.
The Transmission Control Module (TCM) may be a stand-alone unit, but in most cases, it is integrated into a single housing in the Engine Control Module (ECM), which is referred to as the PCM.
To calculate automatic transmission shift energy, the PCM uses multiple input signals from multiple engine transmission sensors. For the transmission to shift gears, electronic shift solenoids interrupt the flow of high temperature. If the solenoids get activated simultaneously, then multiple gears will be engaged, causing problems to the desired gear ratio, making it impossible to achieve.
As with many other error codes related to the automatic transmission, 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 is usually caused by burnt friction material in the fluid, which results in a distinctive odor.
If the PCM determines the engagement of multiple gears in the automatic transmission, it stores the error code and activates the Check Engine Light.
- Transmission slips
- Delayed transmission
- Harsh gear engagement
- Erratic shift patterns
- Strong burnt odor in the transmission fluid
- Disastrous internal (mechanical) transmission failure
- Faulty shift solenoids
- Shorted wiring in the shift solenoids
- Defective PCM or programming error in PCM
How to Check
Start by making sure the transmission fluid is clean and at the appropriate level.
If transmission fluid is low, then there must be a leak. Find the source of the leak and repair it. Refill the transmission fluid at the recommended level.
If the transmission fluid looks dark and smells burnt, then it must be replaced. To replace the transmission fluid, remove the transmission pan (along with the draining torque converter) or flush the transmission (the latter is the recommended step). Whichever you choose, you need to replace the filter as well.
When removing the pan from the transmission, try to preserve the debris that landed on the pan. If the pan looks clear of debris, then you can assume that the vehicle’s clutches are intact. An excessive amount of debris means too much friction (and stuck to the magnet), which means a qualified technician must rebuild the transmission.
With the transmission fluid at the right level, proceed with the diagnostics using a DVOM (digital volt/ohmmeter) and diagnostic information for the specific vehicle. Locate the TSB (technical service bulletin) that matches the error code, vehicle, year, model, engine size, as well as symptoms.
Retrieve all stored codes in the vehicle by connecting the scanner to the diagnostic port. Write the information down before clearing the codes and test-driving the vehicle.
Test-drive the vehicle until the code resets or it enters readiness mode.
If the PCM enters readiness mode, that means the problem is still intermittent and difficult to diagnose. You may need to wait for the condition to develop before you can accurately diagnose it.
If the code resets immediately, then search for the vehicle information source for proper diagnostics. Look for the flow-chart, testing procedures and specifications of the components, connector face views, and pin-out charts.
Test the voltage of the shift solenoids (at key on and engine off) using the DVOM. The shift solenoids usually come with a constant supply of voltage and ground from the PCM at the appropriate time to realize the desired gear ratio.
How to Fix
- Refill or replacement of transmission fluid
- Fixing leaks in the transmission fluid
- Repair of shorted wirings in the shift solenoids
- Replacement of faulty shift solenoids
- Transmission rebuild
This code means there is a serious electrical issue. However, most multiple gear engagement cases are caused by catastrophic mechanical transmission failure. Thus, this must be addressed as soon as possible.