If this is a 2004 or earlier 300M, it is the output speed sensor and is the same one that is in the 41TE/A604 and my local dealer keeps 20 in stock at all times. High failure rate as do the connectors. 42LE/ A606 tranny.
its a 99 300m with a 3.5 h.o the 4 speed autostick its throwing out p0731 1st gear ratio out and p0700 miscommunication i have no speedo witch puts me straight to the output sensor. but idk its more for a second opinion and also where on the tranny will i find the sensor
Pull both input and output and use ohmmeter. Should have about 700 ohms. 1" hex head. If bad (under 500 or more than 1200 ohms), replace. Best bet is if one bad, buy both and replace. $40 is cheeep fix.
fixed it was the output sensor the input was at 690 ohms so almost perfect there was alittle debris so i have a feeling that there will be a rebuild sometime soon. but were back to shifting good again. THE flare up is gone too. have a feeling it was on its way out a while ago. glad i wont have to drive 40+ miles again in second gear.