Code 43, Electronic Spark Control With Spark Control Module: Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.

If conditions for a Code 43 exist, scan tester will display YES. A knock signal should exist at idle unless an internal or system problem exists.
Determines if system is functioning. Usually, a knock signal can be made by tapping on exhaust manifold. If knock signal is not made, try tapping on engine block near sensor. On models with automatic transmission, it may be necessary to place gear selector lever in Drive.
Because Code 43 sets when signal voltage on spark retard line remains low, this test should cause signal on that line to go high. The 12-volt signal should be seen by ECM as a "no knock" signal if ECM and wiring are okay.
This test determines if knock signal is detected on sensor-to-controller line or if ESC module is at fault.
If sensor line is routed too close to secondary ignition wires, ESC module may see interference as a knock signal.
This checks ground circuit to module. An open ground will cause voltage on monitored line to remain constant at about 12 volts. This would cause Code 43 functional test to fail.
This should generate a knock signal to controller. This determines if ESC controller is operating correctly.

CODE 43 ECM TERMINAL & CIRCUIT WIRING IDENTIFICATION

Application	ECM Terminal	Wire Color
3.8L Knock Signal	BB8	Dark Blue
4.3L Turbo Knock Signal	GF9	Dark Blue
All With 4L60-E Transmission Knock Signal	B15	Dark Blue
All With 4L80-E Transmission Knock Signal	D5	Dark Blue

CODE 43 ECM TERMINAL & CIRCUIT WIRING IDENTIFICATION

Application	ECM Terminal	Wire Color
4.3L "L/M" Series CPI & 4.3L Knock Signal	B15	Dark Blue
"S/T" Series Utility Vehicle With M/T Knock Signal	B15	Dark Blue
4.3L "S/T" Series Pickup With M/T Knock Signal	C12	Dark Blue