Transmission drops into neutral while driving. turning key off then on solves temporarily. Once it drops out, can't get into any gear until ignition is cycled. When not acting up runs and shifts smoothly.

The stuck in park is easy disconnect the linkage at the transmission and move the selector red by two notches (by hand) this will place the transmission in neutral if there is resistance chock the wheels release the handbrake and rock the car ( back and forward to take load off the parking parking pawl which is stuck) no electrics is because of the ignition position remove the ignition switch from the column this isolates from the ignition lock and manually move the slide until the engine starts (make sure the hoot & hand brake are applied in case you ******* up the selector job and left it in gear. once the engine starts reconnect the transmission linkage. restart the engine and run the selector through the gears if all is OK.either cut the old ignition lock off the steering column and replace or get a locksmith to remove the key and then re-cut a new key from the spare or from the manufacturers code. all done

These are not valid codes. A valid code is one letter with four numbers behind it.

FAULTY TRANSMISSION SHIFT LOCK SWITCH

You may have a defective valave body solenoid shift relay problem or a wiring issue or the TCM may be defective.

The item that is electrically controlled and it turn controls the gear shifts is the TCM. transmission control module. They are prone to playing up and one of the reasons for that is moisture in the cable connections near the box. Have some one pull all the harness connections concerning the box apart and blowing them clean with air and ensure that they are dry and clean

Test/Service/Replace

The circuit on newer cars with automatic transmissions has a neutral safety, or neutral start switch installed between the ignition switch and the starter. The ignition switch cannot operate the starter motor unless the transmission is in park or neutral.
Late model vehicles with manual transmissions have a starter/clutch interlock switch that requires the clutch to be depressed to the floor.
Neutral Safety Switch
Normal operations of a neutral safety switch provides a quick check for the adjustment of the gear selector linkage.

• To do this, move the selector slowly until it clicks into the PARK position.
• Turn the ignition key to the START position.
• If the starter operates, the PARK position is correct.
• After checking the PARK position, move the lever slowly toward the NEUTRAL position until the lever drops at the end of the NEUTRAL stop in the selector gate.
• If the starter also operates at this point, the gearshift linkage is properly adjusted.
• This quick test also tests the adjustment of the neutral safety switch.
• If the engine does not start in either or both of these positions, the neutral safety switch or the gear selector linkage needs adjustment or repair.

CAUTION
Since you must work under the vehicle to adjust most shift linkages make sure you properly raise and support the vehicle before working under it. Also, wear safety glasses or goggles while working under the vehicle.
A voltmeter can be used to check the switch for voltage when the ignition key is turned to the START position with the shift lever in PARK or NEUTRAL. If there is no voltage, the switch should be adjusted or replaced.

Sounds like a cable to the transmission is not adjusted up right, and/or the neutral safety switch is not adjusted right, if this applies to your Toyota Corolla.

It may be a fault with the gear selector ignition isolation switch on the side of the transmission. As a safety measure the vehicle cannot be started when the gear selector is in anything other than park (maybe neutral). If the linkage between the gear selector and the selector switch on the transmission is a bit slack or the switch on the transmission is faulty the ignition might be disabled as it assumes it is actually left in gear. Check the this selector switch and the shift linkage to it. I think the fault might be easy to correct with adjustment, clean up or exchange

the first problem was the truck wouldn't start. replaced the starter, nothing. replaced the battery and solenoid, nothing. had to touch the starter wire to the battery and got the engine to start. so it looks as though something in the ignition maybe the problem. once i have the truck started i can shift into reverse from park and that's it. i can't shift it into neutral or drive. was hoping to hear it is the ignition switch i need to replace and i don't want to hear its the transmission. please help! thank you.

you have a problem with posibly witht he adjustment on you neutral switch. the transmission has this to prevent starting in gear. it obviosly works fine in newtral so it needs to be adjusted or the lever on your transmission needs adjust ment to allow this sensor to do its job
i hope this helps