searched around on forum and didnt get a rock solid answer for my question. just bought this truck

I have a 96 tacoma 3.4 auto 4x4
transmission shifts up and down perfect, O/D light flashes , check engine light is on. when driving down the road while transmission is running in OD. rpm's raise and lower by less than 500rpm's i assume this is the torque converter locking and unlocking. i can turn OD switch to off and trans shifts down and OD light stays lit. i disconected the battery the other day to reset error codes. check engine light went off, drove the truck down the road about 7miles and no blinking OD light and trans worked perfect. since then parked truck over night then next morning drove truck and back to light blinking and rpm's changing........since then changed the trans fluid just for the heck of it.
i do not know how to check the error codes for the truck. that would be helpful and does it sound like a sensor or what???

 

more info to add......

speedometer does not work.........everything else in cluster works,
took out cluster and speedo cable looks good and connected

has obd code PO0500 = speed sensor failure

can clear codes and transmisson works perfect until i turn truck off and restart.

anything else i can check before buying a speed sensor??

 

learning more and more each day.......time consuming,
fyi
speed sensor 1 is the sensor in the combination meter / instrument cluster. This is what the speedo cable connects to.

NOTE: the service manual for the 96 tacoma has incorrect info about testing this. It says to remove cluster and check resistance between contact A and B on the cluster. The picture shows these contacts as the ones on either side of the sensor. That is incorrect those screws only hold the meter in place. The correct screws to check are the smaller two located beside the sensor. Check resistance on these screws and it should measure a short four times per rotation of sensor. you can insert something in the sensor to turn it.... i used a q-tip that i cut one end off.

my sensor is good, so i checked the other end of the speedo cable and BANG........cable was broken.......
ordering a new speedo cable and i will post results when i get it.

 

Good work! Welcome to YT.

 

speedometer cable solved all problems..........wooo hoo