B1556
CIRCUIT DESCRIPTIONThe module performs internal tests on the EPROM. Each time the module performs a write function to the EPROM, the module reads back the data that has been written and makes a comparison. If the data does not match after 3 consecutive write and verify attempts, the module will set B1556 as current.
CONDITIONS FOR SETTING THE DTC
^ The data read back after a write does not match the data being written after 3 consecutive attempts.
^ The condition must occur when data is being written.
ACTION TAKEN WHEN THE DTC SETS
^ A DTC B1556 is stored in the BCM memory. No driver warning message is be displayed for this DTC.
^ The BCM stores the value being written in another memory address in the EPROM.
CONDITIONS FOR CLEARING THE DTC
^ This DTC requires a successful write in order to change from current to history.
^ The module no longer detects an internal write malfunction.
^ A history DTC clears after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
DIAGNOSTIC AIDS
^ This DTC may be stored as a History DTC with out affecting the operation of the module. If stored only as a History DTC and not retrieved as a current DTC, do not replace the module.
^ If this DTC is retrieved as a Current DTC, replace the module.
TEST
