Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 18 other vehicles, including the 1994 GMC Vandura Special, 1994 GMC Vandura, 1994 GMC Suburban, 1994 GMC Rally Camper Special, and 1994 GMC Rally. However, it is still accessible from the selected car via links, so may be relevant.

ECM/PCM applies and monitors a 5-volt DC signal to knock sensor. Internal knock sensor circuitry pulls this DC signal down to about 2.5 volts. When knock sensor detects detonation, it generates an AC signal which rides back on DC signal to ECM/PCM. Knock signal intensity is dependent upon knock signal level.

Fig 1: Code 43 Schematic ("C", "G", "K" & "P" Series A/T) Knock Sensor W/O Spark Module (Single Sensor)

Fig 2: Code 43 Flow Chart ("C", "G", "K" & "P" Series A/T) Knock Sensor W/O Spark Module (Single Sensor)