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2005 Chrysler 300C Transmission Failure: P0733, P2784, and P0743 Codes - Diagnosis and Repair Guidance

Model: 2005 300c Fault Code: P0733 Posted: 2015-04-17 21:01

Hello, I own a 2005 Chrysler 300C with a Hemi engine and am experiencing serious transmission issues. Last week, while driving on the highway at around 65 mph, I exited onto a local road and slowed to approximately 35 mph for about one mile before turning into a parking lot. At that point, the vehicle suddenly lost drive — it appeared to shift into neutral or fail to engage any gears. Reverse was also unavailable. I had to tow the car home. The next day, after unloading it from the trailer and starting it up, the transmission engaged briefly but then repeated the same behavior: the car would lose drive, as if shifting into neutral on its own — no forward or reverse gear engagement. I scanned the vehicle and found two diagnostic trouble codes: P0733 and P2784. I attempted a fluid change, replaced the transmission filter, conductor plate, and plug to address potential wear issues. After this maintenance, both original codes disappeared. However, a new code appeared: P0743 (Torque Converter Clutch Solenoid Circuit). The vehicle now refuses to shift properly — it seems stuck in first gear and will not move into higher gears or enter manual mode. I am considering replacing the torque converter clutch (TCC) solenoid, but I'm unsure which specific solenoid is correct or whether additional components need replacement. Any advice on diagnosing this issue or recommended next steps would be greatly appreciated. Thanks, R Trout

Related fault codes
P0733P0743P2784
Comments (5)
Anonymous 2015-04-18 07:47

This issue requires thorough investigation. First, verify the transmission fluid level — it's critical for proper operation. Do you have access to a trans-specific scanner? You'll also need to check the voltages of the N2 and N3 input sensors and compare them over time to identify any sensor or control issues. These are the only codes currently present: P0733, P2784, and P0743?

Anonymous 2015-04-18 14:42

After replacing the transmission fluid, filter, and conductor plate, the only code I’ve received is now P0743. The original codes P0733 and P2784 no longer appear.

Anonymous 2015-04-18 16:58

P0743 – Torque Converter Clutch (TCC) Solenoid Circuit This code indicates a fault in the TCC solenoid control circuit. Possible causes include: - Open or short to ground in the TCC solenoid circuit - Internal short within the TCC solenoid itself - Open connection in the TCC solenoid Specifically, check for: (T75) TCC Solenoid Control Circuit – Open (T75) TCC Solenoid Control Circuit – Short to Ground TCC Solenoid Control Circuit – Short to Another Circuit The TCC solenoid (located in the electro-hydraulic control unit) should have a steady 12V supply. All wires connected to the solenoid pack must be checked for proper voltage — any drop or absence indicates a wiring or component failure.

Anonymous 2015-04-18 19:49

Thanks for the detailed explanation! I’ll try these diagnostic steps over the coming days. I believe I now understand what’s going on. It may take a few days to complete the testing, but I’ll keep you updated with my findings and any next steps I take. Appreciate your help!

Anonymous 2015-05-07 19:38

Kev2 – My issue was caused by an open circuit due to one of the pins in the conductor plate breaking when I reconnected it (a poor installation). I replaced the conductor plate with a second unit and cleared the codes. The car ran fine for about a week without any check engine light or transmission issues. Then, I heard one clunk noise and the check engine light came back on. Scanning revealed a new code: P0700 (Transmission Control System Malfunction). I’m not sure if this is related to fluid level — I’ve added 3.5 liters each time after removing the pan. Any suggestions on how to resolve this? Thanks, R Trout