Mitsubishi and Chrysler have a lot in common, and this is one of those things. Now you're into something I'm not familiar with. Chrysler's "limp mode" is to default to second gear and stay there. That pertains to the transmission. As far as how they indicate that to you is different on various models. On older cars the Check Engine light turned on and the diagnostic fault code was # 700 which just meant there was another diagnostic fault code stored in the Transmission Computer.
There isn't much that can go wrong with a torque converter, and of the hundreds of potential fault codes, only a few relate to it. Typical failures include fluid leakage, a vibration at highway speed, and a failure of the clutch to lock up. The clutch only locks up above about 45 mph and in fourth, and maybe third gear, and only after the engine is warmed up. If you have a tachometer on the dash, you can verify the lockup clutch is working by tapping the brake pedal. With the engine warmed up, drive at highway speed, and hold the accelerator pedal perfectly steady. Tap the brake pedal momentarily with your left foot. You should see engine speed pick up about 200 rpm, then drop back down a couple of seconds later. If you don't have a tach., you can usually hear the increase in engine speed too.
If there is a problem with the transmission, you'll need to connect a scanner to read the fault code(s). Sometimes you can get an idea of what kind of problem there is by observing when it goes to limp mode, or fail safe mode. If you start the engine, shift into "drive", and it starts out in second gear right away, (at least for Chrysler products), it's usually electrical in nature and most commonly due to a failed sensor. If it starts out in first gear like it's supposed to, then bangs back to second gear during or right after a shift, it's usually due to slippage in a clutch pack.
Please run down this guide and report back
Friday, November 7th, 2014 AT 2:12 PM