My car goes in first and second gear, but then will not shift into third or fourth gear. What could be wrong with it?

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.

Which transmission does yours have 4T65-E or 4T80-E ?

4T80-E
No Fourth Gear

Checks

Causes

1-2 Shift Solenoid Valve
?€¢
Inoperative
?€¢
Debris
?€¢
Pinched wires

3-4 Shift Valve Bore Plug

Misassembled

4th Band

Burned, slipping, missing

4th Servo Cover

Cracked

4th Servo Pin

Broken, seized

4th Servo Piston

Damaged

4th Servo Seals

Rolled, cut or damaged
4T65-E
Slipping or No Fourth Gear
Slipping or No Fourth Gear Checks
Cause

DEFINITION: A large engine RPM increase is noted in fourth gear, Drive range, with little or no vehicle forward speed increase. First, second, and third gear operation are normal. Shifts into fourth gear are soft or do not occur. Fourth gear ratio is 0.705:1.

Automatic Transmission Fluid Level
Low fluid level

Transmission Main Line Pressure
Low transmission main line pressure

Oil Filter Assembly
• The oil filter assembly (100) is missing, plugged, or damaged.
• The oil filter seal assembly (101) is missing or is damaged.

Control Valve Body Assembly
• The 3-4 shift valve (362) or the 4-3 manual downshift valve (360) is stuck or binding.
• Debris is found in the passages of the control valve body (301) or of the control valve body spacer plate and gasket assembly (396)

Case Cover Assembly
Distortion or damage occurs at the manual valve (404) or at the case cover (401), causing PRN oil leak.

Driven Sprocket Support Assembly
A plugged third clutch oil passage in the driven sprocket support assembly (609)

Fourth Clutch Assembly
• The clutch plates (500-502) are worn, damaged, or misassembled.
• A missing or not seated fourth clutch spring retaining ring (601)
• A damaged spring assembly (602) or piston (603)
• Worn or damaged fourth clutch piston seals (604, 605)

Third Clutch Sprag Assembly
• The sprag (720) was misassembled or backwards on the inner race (661).
• A damaged third clutch sprag assembly (653, 661, 719-721)

Kickdown cable unhooked, attaches next to accelerator petal cable.

BEST TO CODE SCAN VECHICLE COULD HAVE STUCK SECOND AND THIRD GEAR.OR FAULTY OVER DRIVE SOLENOID.CHECK TRANSMISSION FLUID LEVEL IT COULD BE A LITTLE LOW ON TRANSMISSION FLUID.

try reseting the indent cable (by phusing throttle with hand and pushing indent button) that is on cable.

IT SOUNDS LIKE THE RANGE SENSOR ON TOP OF THE TRANSMISSION! IT TELLS THE COMPUTER WHAT GEAR IT'S IN! MY WINDSTAR DID THE SAME THING TILL I REPLACED THE SENSOR!

Sorry, i cant really provide a solution without more details..
But i would say check the transmission fluid (assuming its an auto, since you said when it shifts)
If your transmission fluid is low, add some, then "Cycle" the fluid.
Start in your cars lowest gear (L or 1?) and keep it there for like 15 seconds. Then move up to gear 2, then (3?) or "D", then "N", then "R" then "P" with 15 seconds in between. The whole time your doing this, your holding the brake, and not moving. Your going from the lowest gear you can pick, to park. if your car has the manual mode and doest have "1 / L" or "2", put it in manual mode, keep it in first gear, tap to shift to second, and if it lets you go any higher, go to third, fourth, etc. with 15 seconds in between..
Do this anyways and see if it helps haha.. Good Luck!

transmission shifter module. could also be the final shifter solenoid.

Sounds like the band that controls 3rd and forth gear is almost worn out. Have you followed the recomended interval for transmission fluid changes? What does your trans fluid look like?

With so little info, you can only guess. Most computer controled transmission default to either second or third gear if there is an electrical problem.

The mitubishi trans has sensors on the trans that if they are hooked up wrong, it wont shift. If the fluid is full and clean, odds are you have an electrical problem. Could even be a fuse or the computer.

Hope this helps.