From the 2004 Ford Ranger Owner's Guide
Deactivating/Activating the BeltMinder Feature
Before following the procedure, ensure that the following conditions are met:
*The parking brake is set
*The gearshift is in Park (auto trans) or neutral (manual trans)
*The ignition switch is in the OFF position
*All vehicle doors are closed
*The driver's safety belt is unbuckled
*The parklamps/headlamps are in the OFF position
Activation/Deactivation procedure:
1. Turn the ignition switch to RUN (or ON) position. (Don't start the engine)
2. Wait until the safety belt warning light turns off. (Approx. 1-2 minutes)
*Steps 3-5 must be completed within 60 seconds or the procedure will have to be repeated.
3. Buckle then unbuckle the safety belt 3 times, ending with the safety belt unbuckled. This can be done before or during BeltMinder warning activation.
4. Turn on the parklamps/headlamps, turn off the parklamps/headlamps.
5. Buckle then unbuckle the safety belt 3 times, ending with belt unbuckled.
*After step 5 the safety belt warning light will be turned on for 3 seconds.
6. Within 7 seconds of safety belt warning light turning off, buckle then unbuckle the belt.
*This will disable Beltminder if it is currently enabled, or enable it if it's currently disabled.
7. Confirmation of disabling Beltminder is provided by the safety belt warning light flashing 4 times per second for 3 seconds.
8. Confirmation of enabling BeltMinder is provided by:
*The safety belt warning light flashing 4 times per second for 3 seconds.
*Followed by 3 seconds with the safety belt warning light off.
*Once again, the safety belt warning light will flash 4 times per second for 3 seconds.
9. After receiving confirmation, the deactivation/activation procedure is complete.