QuestionQUESTION: Hope you can suggest the repair needed?
Our van started a hard downshift under 30mph, then the speedometer would bounce around at higher speeds. A day later, van went in limp mode. Read online and replaced the input speed sensor(all they had at that store) and it started the speedo again on the way home. Stopped at our store and replaced the output ss, disconnected the battery and it seemed to drive fine the next day. A few days after that, it starts all over. A friend of the family pulled these codes while we were on vacation: p0720, p0731, p0601, p0700, p1193. I have checked all the wiring, connections,fuses, and changed fluid/filter. I know 601 points to PCM, but when I read about that it says usually no adverse driving issues? Another friend says the TCM is what needs replacing? What is you opinion?
Thank you for you help!
James
ANSWER: Hi James,
I would set aside the 0601 as pertaining to the PCM so would not likely be the cause of a limp mode situation with the tranmission. The 0731 speed ratio error in 1st gear coupled to the still present 0720 leads me to wonder about whether the input speed sensor might be defective or there could be a fault in the 2 wires between the sensor and the TCM. I have heard some criticism of aftermarket sensors but first I would recomment that you check the connection between the sensor plug and the TCM plug. The dark green/violet is the common sensor ground wire which goes to pin 13 of the TCM. The input speed sensor signal wires is dark green/white and goes to pin 52 at the TCM. The output sensor signal wire dark green/brown and goes to pin 14 of the TCM. So check both ground wires to pin 13, and both signal wires for continuity and shake the harnesses while testing. If those seem solid, then consider trying another input sensor. After that it moves toward the solenoid pack as a possibility (though not likely), and beyond that to removal of the trans for internal problems.
The 1193 is about the inlet air sensor on the engine so check its wiring similarly. Its common sensor ground wire is dark blue/dark green to pin 43 of the PCM and its signal wire is dark blue/light green to pin 37.
Good luck.
---------- FOLLOW-UP ----------
QUESTION: Ok-all those wires checked out fine. I did find loss of continuity at the output speed sensor plug from pin 14(green/brown wire)where that wire enters the back of the speed sensor plug. Options?
Thank you again!
AnswerHi James,
I am pleased that you may have found the problem. If the wire is not well connected to the plug my thought would be to get an identical plug with a pigtail of wire from the wrecking yard and then cut off the old plug and splice in the plug from the yard. That sort of a connection, done using solder, and also pre-installing an insulation 'cylinder' on each of the wires before you complete the splice so you can then pull that cylinder over the soldered splice to be sure that the splice is going to be protected from shorting, is the way I would do it. The other approach would be to change out the entire harness for the transmission but that would involve much more re-wiring I would believe.
Roland
