P1740

P1740 on Chrysler/Mopar is TCC or OD Solenoid Performance — the TCM (transmission control module) commanded the torque converter clutch (TCC) lockup or the overdrive (OD) solenoid to engage and the resulting input/output shaft speed ratio didn't match the expected value, indicating slip, sluggish engagement, or solenoid failure. This is one of the most common transmission codes on the Aisin/A604/A606/41TE/42LE/545RFE family. Cheapest-first ladder: scan live transmission data and watch TCC slip RPM at highway speed — a healthy TCC should lock within 50-100 RPM of true 1:1 lockup; persistent slip of 200+ RPM is the converter or its lockup clutch failing. Check transmission fluid level and condition first (Chrysler ATF+4 specifically — substituting Dexron or generic ATF will set this code by itself). Burned/dark fluid means the clutches inside the transmission are already cooking; a fluid change won't save it. Drop the pan, inspect the solenoid pack (the rectangular module bolted to the valve body), and measure each solenoid coil resistance — typical Chrysler spec is 10-30 ohms per solenoid; open or shorted readings confirm the solenoid pack is the failure. Smaller cases: a clogged solenoid screen filter from internal debris will also throw P1740. Don't condemn the entire transmission on a P1740 until you've ruled out the solenoid pack ($150-$300 part), the fluid (cheap), and the TCM connector — full rebuilds run $2,500-$4,500 and are wrong 40% of the time when the real fix was a $250 solenoid pack.

Vehicle-specific patterns: 2003-2010 Dodge Ram / Durango / Jeep Grand Cherokee with the 545RFE 5-speed automatic behind the 4.7L V8 or 5.7L Hemi is the textbook P1740 platform — the solenoid pack fails between 100-150K miles and the symptom is harsh 2-3 shifts plus the code. 1996-2007 Chrysler/Dodge minivan and front-drive sedans with the 41TE / 42LE / A604 4-speed automatic (Caravan, Town & Country, Intrepid, 300M, Sebring) throws P1740 from solenoid pack failure as the #1 cause and from the well-known input/output speed sensor failures as the #2 cause. 2000-2010 Jeep Wrangler / Cherokee with the 42RLE behind the 4.0L throws P1740 from TCC solenoid failure or from a worn converter lockup clutch friction material — a fluid-and-filter service catches it early if the customer notices the highway shudder. 2005-2014 Chrysler 300 / Dodge Charger with the W5A580 (Mercedes-sourced 5-speed) throws P1740 less often but the diagnostic path is the same. Estimated repair: $250 (solenoid pack DIY + fluid on a 41TE) to $4,500 (full rebuild of a 545RFE at a transmission shop).