I just purchased the house and the old owner dont gave me the manual for the garage. I want to set a new code for the pad that is located outside the garage door but I don't have the manual for it. the model is lift master security 031do441

Post the model number of the opener and the model numbers of the remotes. The opener model number is found on the end closest to the door and starts with 139.

Try programming the keypad like this:

Locate the smart/learn button on the rear of the motor unit near where all those white wires go. Press and immediately release this and then walk over to the keypad and key in any 4 digit code you like and press enter.

After programming the keypad see if either remote will work with it. Post this information also.

can you please provide the exact model number of your Security device...

Thanks

there need a computer diagnosis to find out the old code and to replace with a new one

On the rear of the motor unit near where all those white wires go you will find the smart/learn button. Press and immediately release this and then walk over to your keypad and key in any 4 digit code and press enter.

On the rear of your motor unit just to the left of all those white wires you will see a small light. If this light is flashing randomly it is normal. If it is flashing rapidly it is an indication of interference or you have keyed your remote. It really sounds like interference and you will have to do some more checking things.

315 mhz is the radio frequency and you cannot change that. In fact if you purchase a new opener you will get that same frequency.

Your opener was made by Chamberlain Mfg. Co. that also makes Liftmaster. That may be where the confusion comes in.

Most openers are programmed the same. You normally program the house garage opener to accept the new remote. Your garage opener will have a button to press to add in a new remote. Normally you press this and then press the remote in the car and hold until your lights on your opener flash or the garage door closes. (check your manual on your garage door opener)

Try going here and clicking on your specific model. Each models page has instructions included.

http://www.aclickawayremotes.com/Liftmaster/help.html

NOT FAMILIAR WITH CRAFTSMAN MODEL NUMBERS

IF THE UNIT HAS SAFETY EYES YOU SHOULD BE ABLE TO FIND A SQUARE PROGRMING BUTTON.

PRESS AND RELEASE YOU NOW HAVE 20 SECONDS TO INPUT THE NEW CODE ON THE KEYPAD AND PRESS ENTER.

HOPE THIS HELPS

You need to press and release the learn botton (don't hold it or you will clear all the codes)
If the light bulb(s) on your operator are on the front and/or back, the learn botton is on the back of the operator. If the lights are on the sides of the operator then the learn botton is on the right side (looking from the back of the operator and facing the garage door). 
After you press the learn button you have about 30 seconds to press in the new 4 digit code in your key pad then hold the enter button until the light on the operator blinks (about 2 seconds). If this does not work check the battery and try it again.

Try: Click on Sears (below FIXYA) on this website, type in your model No & search. You will get a shortlist; click on your model,below the page u will get Manual/Guides. Click on the blue, you have your manual on line.
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