The car shift in first and second gear but slip in third is this problem common in probe?

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.

Are there any DTC's - diagnostic trouble codes ?in the PCM / BCM ? You have third an fourth below 50 mph but above 50 it down shifts to 2nd gear ,is this what your saying or you don't have 3rd or 4th gears at all ? Which engine did yours come with ? 2.2 L or 4.3 L You trans can set several DTC'S an not all will turn on the check engine light .
DTC B2722 (4.3 L) DTC P0218 (2.2 L) DTC P0218 (4.3 L) DTC P0502 (2.2 L) DTC P0502 (4.3 L) DTC P0503 (2.2 L) DTC P0503 (4.3 L) DTC P0705 (2.2 L) DTC P0706 (4.3 L) DTC P0711 (2.2 L) DTC P0711 (4.3 L) DTC P0712 (2.2 L) DTC P0712 (4.3 L) DTC P0713 (2.2 L) DTC P0713 (4.3 L) DTC P0719 (2.2 L) DTC P0719 (4.3 L) DTC P0724 (2.2 L) DTC P0724 (4.3 L) DTC P0740 (2.2 L) DTC P0740 (4.3 L) DTC P0741 (4.3 L) DTC P0742 (2.2 L) DTC P0742 (4.3 L) DTC P0748 (2.2 L) DTC P0748 (4.3 L) DTC P0751 (2.2 L) DTC P0751 (4.3 L) DTC P0752 (4.3 L) DTC P0753 (2.2 L) DTC P0753 (4.3 L) DTC P0756 (2.2 L) DTC P0756 (4.3 L) DTC P0757 (4.3 L) DTC P0758 (2.2 L) DTC P0758 (4.3 L) DTC P0785 (2.2 L) DTC P0785 (4.3 L) DTC P1810 (2.2 L) DTC P1810 (4.3 L) DTC P1860 (2.2 L) DTC P1860 (4.3 L) DTC P1870 (2.2 L) DTC P1870 (4.3 L) DTC P1875 (4.3 L) .
Shift Pattern This category contains the following topics:
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One forward gear only

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Two forward gears only

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Gear missing or slipping

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No upshift or slipping upshift

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No downshifts

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Non-First gear start

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Refer to First Gear Range Only - No Upshift .

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Refer to Third Gear Only .

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Refer to Second/Third Gear Only or First/Fourth Gears Only .

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Refer to Slips in First Gear .

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Refer to Slipping or Harsh 1-2 Shift .

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Refer to No 2-3 Shift or 2-3 Shift Slips, Rough or Hunting .

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Refer to No 3-4 Shift, Slips or Rough 3-4 Shift .

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Refer to No Part Throttle or Delayed Downshifts .

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Refer to Second Gear Start .

You need new clutch

What make and model, year?

Time for a rebuild

The transmission is slipping

There is a point that a machine works and a point that it stops, you need a transmission rebuild.

Sounds like your synchros need adjusting, can you switch into third at all?

Is it not shifting into OD? It should shift from first to second, then second to third, and third into fourth which is od. I'm not quit sure which forward gear you are meaning.

this problem is a common failure associated with your shift solenoinds inside your tranny. of course a shop is not gonna tell you this because by the time you wanna get it repaired it is usually too late and have already cause damage to your clutch pack and internal parts, thats the main reason why a shop wont mess with just replacing your shift solenoid (aka valve bodie)

Sounds like third gear is gone, You will have to see a dealer or trans shop for that on.