Powertrain Controls - ECM/PCM

DTC 43 Dual Knock Sensor (PCM):

Electronic Spark Control Circuit:

Circuit Description:
The Code 43 circuit consists of two knock sensors with one wire that is spliced together and goes directly to the ECM. There are two Code 43 cheeks performed by the ECM. One check consists on monitoring CKT 496 for a voltage that is above 0.63 volts and below 4.38 volts.

If voltage is either too high or too low, for 2 seconds, Code 43 will set. Once engine temperature reaches 20°C increase from start up or 85°C, MAP reading above 83 kPa and engine speed below 3800 rpm, the ECM will perform a self check by advancing the timing incrementally up to additional 23° advance while anticipating a knock signal. If no knock signal is received during the test, Code 43 will set.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. If an audible knock is heard form the engine, repair the internal engine problem as normally no knock should be detected at idle. The ECM applies 5 volts on CKT 496 which should be present at the knock sensor terminals when the sensors are disconnected.

2. This test determines if the wiring or if the ESC portion of the MEM-CAL is faulty.

3. An improperly installed knock sensor can prevent the knock sensor from grounding to the block.

Diagnostic Aids:
Check CKT 496 for a potential open or short to ground. Also, check for proper installation of MEM-CAL. - Intermittent Malfunctions