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.

Code 43 can be caused by a faulty knock sensor connection at ESC module or ECM. Also, check controller-to-ECM signal line for an open or short to ground.

Fig 1: Code 43 Schematic ("C" & "K" Series) Knock Sensor W/ Spark Control Module

Fig 2: Code 43 Schematic ("P" Series) Knock Sensor W/ Spark Control Module

Fig 3: Code 43 Flow Chart (7.4L) Knock Sensor W/ Spark Control Module