To disable the alarm I have to input the four digit code. input first number of presses, wait for confirmation flash, input second digit wait and so on for the four digits.
If this sounds the same as yours, the way to disable the internal ultrasonic detectors is to press the alarm control button within 3 seconds of removing the key from the ignition.
If you try it turn key till all dash lights come on, wait till the van system checks and most of lights go out, remove key, hold alarm control button until you get conformation flash, exit van by drivers door , then lock van. Alarm takes about a minute to arm.
If this does not work, try running the engine before turning off, removing key and pressing button.
Hope this helps