My car recently was flooded, i replace the soft parts of the transmission as they were the only items within the transmission that was damaged but now, after replacing the computer for the vehicle it has a difficult time getting correct shift rpms and the overdrive doesn't stay in gear what could be the problem?

1. ransmission fluid: Low or dirty transmission fluid can cause a range of transmission issues, including loss of reverse and overdrive. Check the transmission fluid level and condition, and consider flushing and replacing the fluid if it is dirty or low.
2. Transmission filter: A clogged transmission filter can restrict the flow of fluid through the transmission and cause issues with reverse and overdrive. Consider replacing the transmission filter and flushing the fluid to see if this resolves the issue.
3. Shift solenoid: The shift solenoid is responsible for controlling the flow of fluid through the transmission to engage different gears. If the solenoid is faulty or damaged, it can cause issues with reverse and overdrive. Consider having the shift solenoid tested and replaced if necessary.
4. Valve body: The valve body is a complex component within the transmission that helps to control the flow of fluid and engage different gears. If the valve body is damaged or worn, it can cause issues with reverse and overdrive. Consider having the valve body inspected and replaced if necessary.
5. Internal transmission damage: If none of the above issues resolve the problem, there may be internal damage within the transmission that is causing the loss of reverse and overdrive. In this case, it may be necessary to have the transmission rebuilt or replaced.

It's important to address these issues promptly to prevent further damage to the transmission or other components in your Chevy Silverado

So it overheated before you replaced the radiator and continues to overheat? Have you changed the thermostat and attempted to flush the cooling system?

Another item to check would be to make sure the electric cooling fan (assuming your Corsa uses one) is running as the temperature climbs. If your car uses a belt-driven fan, then the fan clutch may be bad or the blades of the fan may be damaged. This assumes no one has removed the fan shroud for some reason.

Izzie: According to http://aamcosocal.com/car-troubleshooting/automatic/trouble-shifting-gears.php "If you begin having trouble shifting or staying in gear, it is usually an indication that an electrical, internal or external transmission part is worn or damaged." "This is a relatively common problem, and it could be caused by any of a number of possibilities:

• An internal transmission repair may be necessary if parts within the transmission are worn or damaged
• External controls for the transmission may simply need adjustment
• External controls may need replacement
• Electrical components may need adjustment or replacement" the thing is, because they are complicated and controlled by a computer, you pretty much have to have a transmission person take a look at it.

Water damage to a vehicle is much more than just appearances. Typically, if a car is flooded to the point that it gets inside the vehicle, it is considered a total loss. If in the US, his insurance may cover it under the Comprehensive policy.
The problems are two-fold:
1. You will never get the moisture out from under all the carpets and in the frame rails. It will rust much more quickly, because these places were not designed to be rust proof.
2. More importantly, there are so many electronics in a car, and they are hidden in all sorts of unexpected places. Body control modules that control the lights, engine control modules that control the engine, dash control modules that control the dash - the list is endless, and all are damaged by water.
The damage is not always immediately evident either. Like the interior parts not designed to be rust free, the internal electronics will also begin to rust or corrode, and what works today may not work tomorrow, or next week, or next month. Eventually, all flood damaged vehicles are besot with gremlins. Saltwater gremlins usually appear within weeks, freshwater gremlins within years.

first off gp sorensen is a manufacturer name on a lot of electronic parts so what exactly did you replace the cable in the transmission for the speedometer is in the back of this transmission pull it out and the gear check the gear for damage if so replace

The water pump is directly behind your fan clutch. Most probably, it's the pump. Shaft seal is already worn out (maybe because of damage bearing). You have to replace the whole assembly or replace the shaft, seal, and bearing. These items are within the repair kit that you can buy in parts store.

the problem of immersion with a battery connected is that all electrical circuits are affected by electrolysis and power flows everywhere
items like the alternator , ECM , sensors, dash gauges and equipment will all be affected
Transmissions will have water in the oil and engines will have mud in the rings and bearings
to get it operational you will have to replace a number of faulty items and the end result may be extremely costly
Better to claim on insurance if you have it and take the car to the wreckers

code 21 is for the oxygen sensor. This controls the mixture of the fuel going into the engine. the sensor may be bad or its connector may be dirty or faulty.

Check for proper engine ground and ground to chassis for dirty or loose connections.

Check these items if problem persists after O2 sensor repair.

MAP
fuel pressure regulator

If the car was recently flooded, there really isn't a whole lot of things that woudl cause it to stop moving. I would say to accept what your mechanic says and go ahead and change the computer.

I had the same problem.. About a year of that problem i lost 5th gear and i had to replace my transmission.