QuestionQUESTION: Hi. I have a 2002 Chrysler 300m. When I drive, the car shifts in "limp-in mode" and sometimes when I come to a complete stop, the car shuts off. Took the car in and got the P0700 reading. Mechanic said it was a problem with the TCM and before I got any work done on the car, I should go to the dealer, see if it can be flash and go from there. So I went to the dealer, they tried to flash with 3 different DBB's and none would allow a flash and it seems there's a problem with my PCM. Now my question is, a tcm is part of the pcm unit right? So I can't just purchase a separate tcm? Or do I have to buy a whole new PCM? I priced some PCM's on ebay where they flash it for you and you would just need it installed. Would that be good?
ANSWER: Hi Kristian,
The pcm and tcm were separate in '99 and by '04 they were combined into a single unit. I don't have an '02 manual so I don't know what you have there. If your '02 still has the separate units they would be found in front of the power distribution box in the engine compartment, pcm and then tcm forward of that. The pcm would have 2 40-pin plugs and the tcm would have a single 60-pin plug. If it has the new combined unit it would also be next to the powerbox but would 4 38-pin plugs, side by side in a row. So look to see which you have and that would tell you what you need to buy if that is the route you pursue.
The 0700 in the absence of any other code does says there is an issue with transmission control module (whether separate or part of the pcm). So do check again using the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window to see the mileage reading changes to show 4-digit numbers preceded by a P. Let me know if you get more than the 0700.
I think if the unit is properly flashed you can install it yourself as that is not a major issue. There nonetheless needs to be some interfacing with a DRB to set the correct mileage and to match up serial numbers, and also to rationalize the theft/security functions. If you want to install a replacement yourself, do so and then see if you can get the vehicle to drive. If not then reinstall the original module(s) and go to a dealer and let them install the new unit and do what is called the 'verifications' on the new unit.
Please let me know whether you find one of two control modules. Thanks.
Roland,
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QUESTION: codes coming up are as follows: P0700, P0731, P0841
AnswerHi Kristian,
It is great that you found two other trans codes as they may explain the problem rather than it being something caused by a faulty control module. I think this removes the control module as the cause, because the 0700 is always set when there is another specific coded trans problem.
The 0841 says that the signal from the low-reverse pressure switch circuit of the solenoid pack is flaky. That could be due to a bad switch or bad wiring. If will cause the limp-in mode you are experiencing. You would check the wiring and if OK then replace the solenoid pack. I would try to remedy this code first. It is inside the box on the driver side of the transmission.
The 0731 code says there is an error in the speed with which the input speed sensor is turning and the output speed sensor is turning compared to what the ratio should be based upon the gears. While this could be a serious problem with the internals or the transmission, it may well be one of the two speed sensors is faulty. My inclination next would be to change the output speed sensor and see it that cures the problem, and if not then try the input speed sensor. These sensors are located on the driver side of the transmission and look identically. The output is at the very far end of the trans, and the input is near the vertical shift rod. Each has a plug (lift tab at edge to release) and then unscrew it. Examine the harness for possible damage to one of the wires which could also cause the code. Torque a replacement in about the same as a spark plug (20 foot-pounds). I hope this does it. If not then you have to try removing the valve body and servicing it. After that it is removal for repair of internal damage.
Roland
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