A Fault Diagnosis Method for Automobile Body Control Module

Abstract

The invention relates a fault diagnosis circuit and a method of vehicle control module. The circuit comprises a sampling resistor in serial connection with contract point end of the relay; VBAT provides power source for load through the relay; an operation amplifier circuit is connected between contact point end of the relay and the central point of the sampling resistor; output of the operation amplifier circuit is connected with CPU's ADC port, for collecting operating current of load to judge open-circuit fault or overload fault of the circuit; output of the operation amplifier circuit is connected with the comparator circuit; and output of the comparator circuit is connected with CPU's IO port, for capturing rising edge interruption to judge short-circuit fault.

Description

technical field [0001] The invention relates to the technical field of automobile electronics, more specifically to a fault diagnosis circuit and method of an automobile body control module. Background technique [0002] In the electronic system of automobile body, there are various electronic loads such as lamps, wiper motors, window motors, rearview mirror motors, and door lock motors. At present, smart power chips or relays are generally used to drive lamp loads and motor loads. [0003] After a short-circuit fault occurs, the smart power chip will trigger the over-temperature shutdown protection before the load fuse is blown. When the chip temperature drops to the normal range, the load will be automatically connected to the load. If the body control module does not detect the short-circuit fault in time and Turning off the smart power chip will cause the smart power chip to be turned off and on to the load repeatedly, and the chip is always at a high operating temperatu...

AI Technical Summary

Problems solved by technology

[0003] After a short-circuit fault occurs, the smart power chip will trigger the over-temperature shutdown protection before the load fuse is blown. When the chip temperature drops to the normal range, the load will be automatically connected to the load. If the body control module does not detect the short-circuit fault in time and Turning off the smart power chip will cause the smart power chip to be turned off and on to the load repeatedly, and the chip is always at a high working temperature, which reduces the service life of the smart power chip

When an overload fault occurs, depending on the magnitude of the current, the time for the smart power chip to trigger the over-temperature shutdown protection cannot be determined. Working with a high current will not only reduce the service life of the smart power chip, but also quickly consume the battery power, causing the power to run out and the engine cannot be started

[0004] In the relay-based load drive circuit, if the relay load is overloaded and short-circuited, the current will greatly exceed the rated operating current, causing the relay contacts or current traces to heat up rapidly. If the overload and short-circuit faults are not detected in time, the relay will trigger Points or current traces are burned, resulting in damage to the body control module or the consequences of igniting the circuit board

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