When it shift from third gear to second gear it makes an abrupt shift. This problem is only from third to second gear, the other gears shift nice and quiet. The transmission is new only 3 months old.

There could be several reasons why your 2005 Dodge Magnum is experiencing problems with shifting from second to third gear and then suddenly hitting reverse, including:

1. Transmission Fluid Level: Low transmission fluid level can cause erratic shifting, slipping, or stalling in your vehicle. Make sure to check your transmission fluid level and add if necessary.
2. Shift Solenoid: A faulty shift solenoid can cause problems with shifting in your transmission. The solenoids control the flow of transmission fluid through the valve body, which controls the shifting of gears. If the shift solenoid is failing or has failed, it can cause the transmission to slip, shift erratically, or get stuck in a gear.
3. Transmission Pump: The transmission pump is responsible for pumping transmission fluid through the transmission and to the torque converter. If the pump is failing, it may not be able to pump fluid properly, leading to problems with shifting and slippage.
4. Valve Body: The valve body controls the flow of transmission fluid through the transmission and directs the shifting of gears. If the valve body is failing, it can cause the transmission to shift erratically or get stuck in a gear.
5. Transmission Control Module (TCM): The TCM is responsible for controlling the transmission's shifting and overall performance. If the TCM is failing, it can cause the transmission to shift erratically or get stuck in a gear.

It's best to have a qualified mechanic diagnose and repair the issue as they will have the necessary tools and expertise to properly diagnose and fix the issue.

see if this link helps you out.... My 2004 chevy trailblazer won shift from second to third gear Google Search

What make and model, year?

Here is what the service manual says about the EPC solenoid, the processor looks at allot of different inputs to command the solenoids, such as Throttle Position Sensor, Vehicle Speed Sensors, Transmission Range Sensor and RPM signal, The PCM controls the shift patterns for the transmission. Electronic Pressure Control (EPC) Solenoid
The electronic pressure control (EPC) solenoid is located on the main control valve body and is controlled by the PCM. The EPC controls line pressure used to apply and release clutches and bands in the transmission.
The 2-3 shift solenoid is located on the main control valve body and is switched on and off by electrical signals from the PCM. The 2-3 shift solenoid activates the 2-3 shift valve which controls the automatic shifting between second and third gear. Second gear is established when the 2-3 shift solenoid is switched on. The 2-3 shift solenoid is switched off when vehicle speed increases and requires a second to third gear upshift.
The 3-4 shift solenoid is located on the main control valve body and is switched on and off by electrical signals from the PCM. The 3-4 shift solenoid activates the 3-4 shift valve which controls the automatic shifting between third and fourth gear. Third gear is established when the 3-4 solenoid is switched off. The 3-4 shift solenoid is switched on when vehicle speed increases and requires a third to fourth gear upshift.

when has the last time you had a trans serv. done on it? if you take it to a shop the will tell you that you need a rebuild. thrid gear and over drive are about burned up.

Sam,

I would start with a transmission fliud and filter service.

I would then have the trasnmission checked out by a transmission shop. The transmission most of the time has the direct drum band is starting to go. The shops can rebuild it no problem, This is a very common failure wiith the trasnmission.

Good Luck

Most likely your shift cable (from the selector to the transmission) is worn, maybe needs lubrication. Mine had a similiar problem, but had to shift it into neutral and back up to get it in reverse. A new shift cable solved the problem.

sounds like what happened to my camaro. it sounds like a stuck valve. i suggest taking it in for an estimate at a transmission specialist.

It seems in the manual transmissions the first gear to go is 3rd gear..
signs of a failing trans