Today, the computer operates almost every system in your car–including the line stress, shift timing, sequence, and feel of the transmission. The vehicle speed sensor offers feedback to assist regulate ABS, combination of fuel, injection of fuel and operation of transmission. The manifold absolute pressure (MAP) sensor and throttle position sensor (TPS) provide the load data for the engine that is used to handle the transmission shift and downshift when driving up an incline or when placing the pedal on the metal.
Failing code circumstances or "Safe Mode" happens when the computer of a vehicle has an issue with the logic. If the signal value sent to the computer by a sensor does not fall within the manufacturer's pre-programmed range, it will move to "secondary" programming. These processes are intended to safeguard the transmission against further harm that the signal mistake could cause.
The transmission will function usually as long as the computer receives signals from the MAP, TPS, car velocity and other sensors falling within their "ordinary" ranges based on present circumstances. However, as stated above, it will move to secondary / emergency operation if it gets a signal outside the anticipated range.
The precise steps made in secondary operation are determined by the logic of the computer as programmed by the manufacturer and depend on how far the signal is (if there is any signal at all) outside the acceptable range. If the value is greater than the largest parameter, it could respond differently than if the value is smaller than the smallest permissible value. Safe Mode's Protective Actions Check Engine Light-Safe Mode If the signal value was not far enough outside the range to show a mechanical failure, the first thing the computer will do is switch the check engine light on to warn the driver that they should have the car checked out using a code reader / diagnostic device to see if there are any "soft codes" mentioned. Soft codes may show a failure or breakdown of a low priority sensor. After restarting your vehicle, if the light passes away, it could imply that the sensor failed only once owing to a loose link or it could be a sign that its situation is getting worse. Typically, critical functionality is not affected by this type of problem, but if the problem is not solved, it can have a negative effect on the vehicle's performance or fuel efficiency.
Now, if the signal value from a high priority sensor (needed for critical tasks) is dangerously far from the acceptable range of operation, the computer switches to secondary "survival" mode. It's called a "hard code." The computer is shutting off the electronic shift solenoids in this mode. This disables the capacity of the transmission to change gears and leads to single usable gear default–generally second or third. Additionally, the pressure in the fluid lines of the transmission is set to high to prevent damage to the bands and clutches. To avoid the clutch pack from sliding dangerously, the times that regulate the line stress are set to "full on." If your vehicle does this you need to get it check out by a transmission shop asap.

If your Car is in Safe Mode Bring it by Eagle Transmission Shop in Dallas /Mesquite for a Free intial Check Out.