1999 Saturn SL2 check engine codes 705&706

first of all thank u so much for ur donation.the codes u have are for ur selector switch.its what tells ur computer what gear u shifted into with ur shifter.the most likely cause is a bad selctor switch.the only way to really test it is to get a code scanner that reads transmission data on ur car.if u had one u would go to transmission data and look at selctor switch data and watch what it reads on the screen compared to what gear u put it in with the shifter.if any of the gears read invalid then u need a new selctor switch.u do this with the car not running.let me know what u find.

i don't have a scan tool that will test the transmission. I will change the switch. what is the name of it and what is the procedure of replacing it. would it be my Neutral Safety Switch? would a haynes explain how to chance that switch?

there about 50 for the selector switch aka neautral safety.i honestly dont know if haynes or chilton has the directions for that replacement i have only used the saturn factory shop manuals.ok u will need a volt ohm meter to adjust the switch when u replace it.ill just explain to u how to change it save u like 20 for the manual so u can put that towards a meter if u dont have one.the easiest way to get to it is thru ur drivers wheel well to replace it.set the brake block the wheels put the car on a jack stand on the drivers side so u can take the whell off.then u can pull the plastic side panel take that off.now u can see the selector switch.unplug the three connectors.take a good sized flat blade screwdriver pop the shifter cable off.now remove the 13mm nut that holds the shifter arm on that the cable goes too.pry off the shifter arm now remove the two 13mm bolts that hold it on too the transmission.now remove the selector switch it should slide off the shaft.now slide the new one on and reinstall everything except leave the two 13mm bolts just loose enough to move the selector switch back and fourth.plug in the two side plugs but not the top one.shift the car into drive 4 the gear u normal put it in to drive. with the car not running the ebrake on the wheels blocked.go from above and hook up ur meter with aligator clips to the two copper tabs that stick up with them not touching.now put the meter on low scale ohms like 200 scale.now slowly move the selector switch back and fourth while watching the ohms reading.the closer to 0 ohms the better when u get the reading u want tighten the bolts down.make sure the reading is still good after tightening it down.now remove the meter and plug that top plug in.ur done let me know what happens and how it goes.

when i do it the plug that i put the meter on is the top plug?

Yes the two tabs that are on top the one the plug goes to and the other one that is just used for adjustment.u put black and red on them.