Resetting the Sargent & Greenleaf models 6120, 6121, and 6123

By John Soderland, CPS, CML on September 28, 1998


The Sargent & Greenleaf electronic locks can be reset, the MRC can be added, deleted, or changed after initial programming.

This procedure can be accomplished in the field with common tools. With practice, resetting can usually be accomplished in a few minutes.

The tool you will make and use in this process, is a piece of bell wire, solid strand, approximately 6 inches long, with one half inch of insulation stripped off of each end, each end rolled into a single loop approximately one-eighth of an inch inside diameter. Exact size not critical, but wire must be flexible, and ends looped to a rounded shape to prevent damage to the lock processor.

The first step is to determine if the lock is capable of accepting an MRC. Install fresh alkaline batteries, and press *6#. If one-second long “error” tone is heard, the lock is likely to be a 6121, which can be reset using a second procedure, listed below, but is not capable of accepting an MRC. If, when *6# is pressed, no tone is heard, this indicates the lock is capable of accepting an MRC, even if none had ever been previously set (6120, 6123).

Remove the lock from the container. You may leave the keypad base mounted, but the lock case and keypad must be removed. Break cover seal by cutting with razor or knife (Note: seal must be broken, and of course, this will void any remainder of the two-year manufacturer warrantee). Carefully peel the rubbery cushion material and wire away from the lock body, up to the crack between the cover and case. Remove the cover screws if still installed, and carefully remove cover from lock body, making sure not to separate too far, as there is short wiring connections between cover and case.

IMPORTANT **Unplug the small 2 wire connector which connects the motor to the circuit board. ** Connect the keypad with fresh alkaline batteries installed. Locate the large processor chip on the circuit board.

These locks are reset using the mentioned wire tool, by electrically entering data directly into the processor, until an “error” is recognized by the processor.

The processor chip, which is the large chip on the circuit board resembles a “centipede” with left legs, and right legs. Orient the circuit board so the pins (legs) of the processor point to the left and right. You will use the wire loops of the wire tool, to cross 2 legs at a time on the left side, and 2 legs at a time on the right side (this is one reason for the looped ends).

Holding one end of the wire tool in each hand, run the left loop gently up and down the left legs of the processor, and at the same time, run the right loop gently up and down the right legs of the processor. You should hear “click”, “beep” and “boop” sounds. If sounds are not heard, rub the legs a little harder until they start, as there may be a thin film on the legs, which may need to be worn through. Sometimes, the sounds stop being produced, and it helps to unplug the keypad, wait 30 seconds, plug it in again, and continue. Continue doing this, as this adds data to the processor. Stop when an error is encountered, which will make the keypad “beep” or “buzz” continually. Unplug the keypad. Wait 60 seconds, then plug keypad back in.

The keypad should now be silent. If you are resetting a lock capable of accepting an MRC (as determined before), press *-*-#. If no tone is heard, the lock is likely to have been reset. Plug the motor into the circuit board. Wait 10 seconds. Enter 1-2-3-4-5-6-#(You may need to enter this two times). If the bolt retracts, the lock is now reset, and an MRC can be added if you do so before you change the master combination from 1-2-3-4-5-6. If the bolt does not retract, UNPLUG the motor, and try again. Forcing an “error” into the processor does not always reset the lock on the first try. Often, the process must be repeated several times to accomplish the reset.

Occasionally, the reset is accomplished without the keypad emitting the continuous “beep” or “buzz”. If you feel that after a while you are getting nowhere, try pressing *-*-#. If no tone is heard, the lock is likely to have been reset, so plug the motor in, and perform the test outlined above.

On the 6121 lock, the processor has no MRC capability, but can be reset as well. Follow the same procedure as for the 6120,6123, but when you plug the keypad back in after the 60 second wait, enter 7-4-*-1-2-3-4-5-6-#. If you hear 5 beeps, the lock is reset. Test by plugging the motor in, and entering 1-2-3-4-5-6-#. If the bolt retracts, the lock is reset.

You are free to copy and distribute this information, but only in its complete form, with the following credits included, please.

John Soderland, CPS, CML

Special thanks to:
Brian Costley
Ron Jewell
Mike Potter

And especially: Wife Debra, who let me spend many Countless hours, late at night, “Beeping and Booping” At the kitchen table, while she was trying to sleep.