P0899: Transmission Control System MIL Request Circuit High

Last Updated on May 27, 2020 by themechanic

An automatic transmission allows the gear ratios of a vehicle to change automatically as you are driving. This means you don’t have to shift gears with a gear stick as you do in a manual transmission vehicle. Just step on the gas pedal to accelerate faster, and the torque demand will be met by the automatic transmission. Anyone who is a new driver should always practice with an automatic transmission vehicle because it is the easiest to drive.

There is a transmission control system in the vehicle which transmits information about the current gear ratios to the powertrain control module. That is how the gear ratios can shift properly on their own because the module receives information based on the driver’s actions and then implements the gear ratio changes needed to sustain those demands.

If the transmission control system fails at transmitting its information to the powertrain control module, then shifting problems in the transmission could occur. You may also experience a weak fuel economy because your engine will consume more fuel. Other symptoms may include engine stalling and slipping. These are drivability issues which can put the safety of you and others at risk on the road.

Run a diagnostic check on your powertrain control module to verify the problem. If you receive trouble code P0899 on the display screen, then it means the communication circuit of your transmission control system contains a high-voltage signal. That is why the information is not being transferred correctly. The cause of the problem may relate to a bad engine control unit, wiring damage, engine control unit software problems, or a bad transmission control module.

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These are all problems which require an expert auto mechanic to fix. The most expensive problems to fix would be a bad engine control unit or bad transmission control module. Wire damage and software issues are less expensive to fix. However, any issues with the software should be dealt with by the dealership that sold you the vehicle. They have the necessary technology to update the software of the engine control unit to ensure it is functional and ready to serve your vehicle.

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