DTC 43 Electronic Spark Control (ESC) Circuit
CODE 43, ESC ERROR, W/ESC MODULE
NOTE:Test numbers refer to numbers on diagnostic chart.
If conditions for a Code 43 exist, "Scan" tester will indicate knock signal presence. Knock signal should not exist at idle unless an internal or system problem exists.
Determines if system is currently functioning. Usually, a knock signal can be generated by tapping on exhaust manifold. If knock signal is not generated, try tapping on engine block closer to sensor.
Because Code 43 sets when signal voltage on spark retard line remains low, this test should cause signal on that line to go high. Control module should see 12-volt signal as a "no knock" signal if control module and wiring are okay.
This test will determine if knock signal is being 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 induced interference as a knock signal.
This checks ground circuit to module. An open ground will cause voltage on monitored line to constantly remain about 12 volts. This would cause Code 43 functional test to fail.
Contacting sensor-to-controller wire using a test light connected to 12 volts will generate a knock signal to controller. This will determine if ESC controller is operating correctly.
Code 43 can be caused by a faulty connection at knock sensor, ESC module or control module. Check controller-to-control module signal line for an open or short to ground. Check for poor connections and damaged harness. Inspect control module harness connectors for backed-out sensor signal and ECM input signal terminals, improper mating, broken locks, improperly formed or damaged terminals and damaged harness. If connections and harness are okay, monitor knock signal parameter using "Scan" tester while moving related connectors and wiring harness. If failure is induced, knock signal will abruptly change. This may help to isolate malfunction.
Fig. 38: Code 43
Fig. 39: Code 43, Schematic, "D" Body, W/ESC Module, ESC Error
Fig. 40: Code 43, Flow Chart, ESC Error, W/ESC Module
CODE 43, ESC ERROR, W/O ESC MODULE
NOTE:Test numbers refer to numbers on diagnostic chart. If an audible knock is heard from engine at idle, repair internal engine problems before proceeding.
If tapping on engine does not produce a knock signal on "Scan" tester, try tapping engine closer to sensor before proceeding.
ECM supplies a 5-volt reference signal on knock sensor line. With knock sensor connected, this signal is pulled low to about 2.5 volts. Knock signal, which is an AC signal, rides on this 2.5-volt DC signal.
This test determines if knock sensor is faulty or if ESC portion of MEM-CAL is faulty.
Check knock sensor signal circuit for a potential open or short to ground. An open knock signal circuit would cause 5-volt reference to remain high at ECM knock signal terminal. A short to ground in knock signal circuit would cause 5-volt reference signal to pull low to near zero volts. Resistance to ground through knock sensor should be 3300-4500 ohms. Also check for proper installation of MEM-CAL
Sunday, September 19th, 2010 AT 4:47 AM