DTC 43

DIAGNOSTIC CHART





WIRING DIAGRAM

INSPECTION PROCEDURE

Circuit Description:
KS is accomplished with a module that sends a voltage signal to the Engine Control Module (ECM). As the KS detects engine knock, the voltage from the KS module to the ECM drops, and this signals the ECM to retard timing. The ECM will retard the timing when knock is detected and rpm is above about 900 rpm.
DTC 43 means the ECM has been low voltage at CKT B7 for longer than 5 seconds with the engine running or the system has failed the functional check.
This system performs a functional check once per start up to check the KS system. To perform this test the ECM will advance the spark when coolant is above 95°C and at a high load condition (near Wide Open Throttle). The ECM then checks the signal at "B7" to see if a knock is detected. The functional check is performed once per start up and if knock is detected when coolant is below 95°C (194°F) the test has passed and the functional check will not be run. If the functional check fails, the "Check Engine" Malfunction Indicator Lamp will remain "ON" until ignition is turned "OFF" or until a Knock Sensor (KC) Signal is detected.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. If the conditions for a DTC 43 are present, the "Scan Tool" will always display "YES". There should not be a knock at idle unless an internal engine problem, or a system problem exists.
2. This test will determine if the system is functioning at this time. Usually a KC signal can be generated by tapping on the right exhaust manifold. If no knock signal is generated, try tapping on block close to the area of the sensor.
3. Because DTC 43 sets when the signal voltage on CKT B7 remains low, this test should cause the signal on CKT B7 to go high. The 12 volts signal should be seen by the ECM as "no knock" if the ECM and wiring are OK.
4. This test will determine if the knock signal is being detected on CKT E or if the KS module is at fault.
5. If CKT E is routed to close to secondary ignition wires the KS module may see the interference as a KC signal.
6. This checks the ground circuit to the module. An open ground will cause the voltage on CKT B7 to be about 12 volts which would cause the DTC 43 functional test to fail.
7. Contacting CKT E with a test light to 12 volts should generate a KC signal. This will determine if the KS module is operating correctly.

Diagnostic Aids:
DTC 43 can be caused by a faulty connection at the knock sensor at the KS module or at the ECM. Also check CKT B7 for possible open or short to ground.
Refer to "Intermittents" in "Symptoms".