Circuit Description

The control module Programmable Read Only Memory (PROM) contains data which is essential to the operation of the engine and transmission. When ignition is on, values in all of PROM memory locations are added together and compared to a calibrated checksum number. If these 2 numbers are not equal, DTC will be set. This test determines if any address locations have become corrupt. DTC will set when VCM is unable to correctly read data from EEPROM memory.