DTC 43

Circuit Description

The detonation sensor is used to detect engine detonation. The ECM will retard the electronic spark timing based on the signal being received.

The circuity, within the detonation sensor, causes the ECM's 5 volt reference to be pulled down so that under a no knock condition, CKT 26 would measure about 2.5 volts.

The detonation sensor produces an AC signal, which rides on the 2.5 volt DC signal. The amplitude and signal frequency is dependent upon the knock level.

There are two tests run on this circuit by the ECM to determine if it is operating correctly. A Code 43 will be set if:

^ CKT 26 becomes open, or shorted to ground the voltage will either go above 3.5 volts or below 1.5 volts. If either of these conditions are met for about 0.6 seconds, a code 43 will be stored.
^ The detonation sensor produces an AC signal longer then 3.67 seconds in duration, during 3.9 second. Code 43 will be stored.

The tests are performed when:

^ Coolant temp. is over 50°C (122°F).
^ High engine load based on MAP and rpm between 1,000 and 5,800.