Common Computer Failures

Listed below are some of the more common causes of computer failures. The following list of failures applies to all types of control modules and not just ECMs.

External damage Moisture contamination Physical damage from vehicle accidents. Improper handling allowing static discharges to enter the ECM circuits. High voltage or high current passing through the circuits. Low voltage caused by faulty batteries and failed alternators. Poor ground connections can impede the operation of the ECM. Misapplication of components being used with computer controls.

What happens when the wrong parts are installed?

A Misapplication of components (i.e. relays) can quickly damage an ECM. When the control side of a relay is activated a magnetic field is developed. The magnetic field closes a set of contact points and high current is allowed to flow through the points to the device. When the relay is deactivated the magnetic field collapses. This magnetic collapse produces high voltage (as much as 100 volts). If this voltage spike is not controlled, it will flow back into the ECM and destroy the switching transistor. Most of the relays used in computer control systems, incorporate a resistor or a clamping diode that keep voltage spikes from entering the ECM. Make sure you look up the part by application and not by appearance.

The connectors are the same!

No ECM Protection

Diode Protects ECM