Servicing the Engine Management System (ECM/PCM)
SAFETY CONCERNS AND CAUTIONS
Electronic components are easily damaged if proper precautions are not taken.
- Static electricity can damage solid-state components. It is always good practice to wear a grounded static strap when handling these components.
- Never use a test lamp or an analog meter when testing solid-state components.
- Be sure that spark plug wires and any other circuits developing a high voltage are not routed in the same path as the solid-state component.
- Do not apply a current or ground to any portion of a solid-state component unless you are sure of its operation.
- Jump stating a vehicle with the jumper cables reversed can destroy a solid-state circuit. Remember: red to red and black to black.
- Be careful when handling sensors, as they can lose their calibration if dropped or mishandled.
- Refrain from wearing jewelry when working on electronic components.
- Before removing any ECM, disconnect the battery ground lead.
- Never disconnect the battery from the on-board electrical system while the engine is running.
- Never subject the ECM/PCM to temperatures above 80 degrees Centigrade.
- Ensure all cable harnesses are solidly connected and battery terminals are thoroughly clean.
- When charging the battery, disconnect it from the vehicle’s electrical system.
- Never disconnect or connect the cable harness plug at the ECM/PCM when the ignition is switched on.
- Before attempting any electrical arc welding, disconnect the battery leads and the ECM/PCM connectors.
- When steam cleaning engines, do not direct the steam cleaning nozzle at the ECM/PCM components.
- Use only test equipment specified by the vehicle manufacturer, and observe the recommended test procedures for that test equipment.
- When using a digital multimeter for voltage tests, ensure a digital meter with an internal impedance rating of at least 10 million ohms per volt (10 mega-ohms/volt) is used.
HANDLING AND ELECTROSTATIC DISCHARGE
Static electricity can harm delicate components inside your computer. To prevent static damage, discharge static electricity for your body before you touch your computer or any of its electronic components, such as the PROM. You can do so by touching an unpainted metal surface, or wear a static wrist strap. You can also take the following steps to prevent damage from electrostatic discharge (ESD):
- When unpacking a computer or component from its shipping carton, do not remove the component from the anti-static packing material until you are ready to install the component. Just before unwrapping the anti-static packaging, be sure to discharge static electricity from your body.
- Handle all sensitive components in a static-safe area. If possible, use workbench pads.