Knock Sensor Circuit (Models Using Knock Sensor With Internal Spark Controller Module)
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1998 GMC Suburban, 1998 GMC Pickup, 1998 GMC Cab & Chassis, 1998 GMC C3500 HD, and 1998 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.
- An open or short circuit on knock sensor wire to PCM/VCM will set a related trouble code. A false detonation signal will not cause PCM/VCM to set a code.
- If a scan tool is available, connect it to Data Link Connector (DLC). Tap on engine next to knock sensor and note "knock" parameter. Knock should be indicated on scan tool.
- If a scan tool is not available, connect tachometer to engine. Start engine and hold RPM above idle. Using a metal object, tap on engine close to knock sensor. A noticeable decrease in engine RPM should occur. If no RPM decrease occurred, check knock sensor to PCM/VCM circuit.
- On vehicles equipped with automatic transmission, it may be necessary to place transmission in Drive for timing change to occur.