DTC B1000: Control Module Malfunction: Description

An internal fault detection is handled inside a control module. No external circuits are involved. A control module runs a program to detect an internal fault when power up is commanded. Only requirements are voltage and ground. This program runs even if voltage is out of valid operating range. A control module first writes information to a cell, or address, then adds 0.25 to value, and calculates a check sum. If this checksum minus 0.25 is not equal to a cell value, a module will store DTC. A history DTC clears when a control module ignition cycle counter reaches reset threshold, without a repeat of malfunction.