Powertrain Controls - ECM/PCM

DTC 43 Knock Sensor (KS) Trouble Chart:

Knock Sensor (KS) Circuit:

CIRCUIT DESCRIPTION
The Diagnostic Trouble Code (DTC) 43 circuit consists of two knock sensors with one wire that is spliced together and goes directly to the Powertrain Control Module (PCM). The PCM check consists of monitoring CKT 496 for a voltage that is above 0.63 volt and below 3 volts.

DTC 43 WILL SET WHEN
The voltage is either too high or too low, for 10 seconds, DTC 43 will set.

ACTION TAKEN (PCM WILL DEFAULT TO)
The PCM will turn "ON" the Malfunction Indicator Lamp (MIL).

DTC 43 WILL CLEAR WHEN
Conditions for fault are no longer present and Tech 1 scan tool clear DTCs function is used or 50 ignition switch keycycles have passed with no further faults or ignition switch is turned "OFF" and ECM "B" fuse is removed for 10 seconds.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart:

1. If an audible knock is heard from the engine, repair the internal engine problem as normally no knock should be detected at idle.
The PCM 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 KS portion of the PROM (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 PROM (MEM-CAL).