EXHAUST NOISE
| WARNING | To avoid being burned, do not service the exhaust system while it is still hot. Service the system when it is cool. |
Electromagnetic Interference & Electrical Noise
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 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 for proper performance of the generator. See ON-VEHICLE TESTING in appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
- If a DTC is determined to be intermittent, and tests in this section do not reveal a problem, see FREEZE FRAME/FAILURE RECORDS DATA feature using the scan tool. This information can be reviewed and compared to the typical Scan Tool Data List values or to data values taken from a similarly equipped known-good vehicle. See appropriate «PID VALUE CHARTS»(ref-157349-S16055647892003081100000) in PID VALUE CHARTS - VIBE article.