Electromagnetic Interference (EMI) & Electrical Noise
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
Some electrical components or circuits are sensitive to Electromagnetic Interference (EMI) or other types of electrical noise. Perform the following procedures:
- Check for a misrouted harness that is too close to a high voltage or high current device. This condition may induce electrical noise on a circuit that could interfere with normal circuit operation. Check for wires that are too close to the following devices:
- Secondary ignition components.
- Motors.
- The generator.
- Determine whether the electrical system interference is caused by a malfunctioning relay, PCM driven solenoid or switch. These components may cause a sharp electrical surge. Normally, the problem will occur when the malfunctioning component is operating.
- Determine whether non-factory or aftermarket add-on accessories are installed in the vehicle. These accessories may lead to an emission related OBD-II failure. Determine if any of the following non-factory or aftermarket add-on accessories is causing the intermittent:
- Lights.
- 2-way radios.
- Amplifiers.
- Electric motors.
- Remote starters.
- Alarm systems.
- Cell phones.
- Check for an open diode across the A/C compressor clutch and for other open diodes. Some relays may contain a clamping diode.
- Check the generator for a bad rectifier bridge that may be allowing AC noise into the electrical system. See ON-VEHICLE TESTING in appropriate GENERATORS & REGULATORS article in ELECTRICAL.