I love my automatic lock and unlock function on my 2002 SR5. Normally when I put the vehicle into drive all the doors automatically lock, and when I put in park they all obediently unlock for me, but a few weeks ago it stopped working.

I've been searching the interwebs and t4r in particular, but nothing seems to come up other than the method to turn the auto lock function on or off. I've tried the ignition and door lock dance to see if turning it on or off might work, but nothing happened after five times following the instructions to turn it off and on. I suspect that method only works for those with the OEM security system. I am 95% sure I don't have an OEM security system (no black box under my seat or light on the dash).

All of the power locks otherwise function normally via the fob and driver's door.

I'm not sure where to start troubleshooting this problem. I'm a total newb when it comes to electrical troubleshooting, though I am trying to learn. I was thinking of starting with testing or replacing the sensor that tells the vehicle when it is in park or not, but after that I'm at a complete loss.

If anyone has some experience or expertise with this auto lock system, I'd appreciate some help.

And in case anyone is not familiar with the method for enabling/disabling the auto lock/unlock function, here is what I've found. Unfortunately, it has proven to be of no use to me.

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The factory setting for the automatic door locking and unlocking function is on.

1: Sit in the drivers seat with the drivers door open.

2: Insert the key into the ignition switch and turn it to on (not acc) 5 times (on-lock, on-lock, on-lock, on-lock, on) within a 10 second period. The status monitors LED turns on, and the piezo chirper sounds once.
***You must perform the next steps within 30 seconds***
Select the operating mode:

Automatic door locking and unlocking on: Close the drivers door. Turn the ignition switch to the lock position. The piezo chirper sounds once, and the exterior lights flash once.

Automatic door locking and unlocking off: Close the drivers door once, then open and close it one more time. Turn the ignition switch to the lock position. The piezo chirper sounds twice, and the exterior lights flash twice.

If you do not turn the ignition key to lock, or exceed 30 seconds during the programming steps, the status monitor's LED will turn off and the previous operation mode will remain.

I'm also interested in this.

I previously had an '02 SR5 Sport that would auto lock/unlock. Stupid me sold it for a '13 and then decided that was a dumb move!

I found another '02 SR5 (non-Sport) that came with one key that would not lock the doors externally.
LSS, I was able to get a new key and program a new fob but this SR5 doesn't have the lock/unlock function the previous poster talks about (also doesn't have the LED to the left of the steering wheel.)

I'm assuming the functionality was a 'creature comfort' and there's a part that controls that function (associated with the LED) that wasn't available on the SR5.

Any info on part number, or correction of thought (!) is appreciated!

The black box is Port installed USDM, the 99-02 should have the immobilizer for limited models and maybe others, which has the option you're after, you seem to be missing the last -lock step in your description to enter functions setup AFAIK, if your battery is low or weak you will need to charge it up before hand or put a charger on while doing this, and with the hood closed as there is a security sensor for the hood latch aswell.

My 2000 model locks the doors as soon I turn the key on IGN ON. Thanks for sharing the tutorial, I'll try and disable it. Dont like it at all