Normal Operation

WARNING: This page is about a different car, the 2008 Mercury Mariner and 2008 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

The Smart Junction Box (SJB) monitors the reference circuits CPK29 (GY/BU), CPK30 (VT/GN), and CPK31 (YE/GN) for the keyless entry keypad. The keypad is grounded through circuit GD182 (BK/GY). When an individual keypad button is pressed, an individual or a combination of the reference circuits are connected to ground. The SJB then determines which button was pressed based on which circuit(s) has a ground signal. Once the SJB determines that the 5-digit personal entry code, or the factory set 5-digit code has been entered on the keypad, the SJB then energizes the driver door unlock relay to unlock the driver door.

To unlock all the doors, the 3/4 button must be pressed within 5 seconds of the 5-digit code being entered.

To release the liftgate window, the 5/6 button must be pressed within 5 seconds of the 5-digit code being entered.

To lock all the doors, the 5-digit code does not need to be entered. Press the 7/8 and 9/0 buttons at the same time.

DTC B2A26 (Keypad Switch Circuit Failure) - a continuous and on-demand DTC that sets when the SJB detects a short to ground on any of the keypad input circuits. This DTC may also set if any of the keypad buttons are pressed for longer than 2 minutes.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Keyless entry keypad
SJB