With VCM

DTC 38 (VCM):

KS Circuit (VCM):

Circuit Description:
The DTC 38 circuit consists of two knock sensors with one wire which is spliced together and goes directly to the VCM. This check consists of monitoring CKT 496 for a voltage above 3.18 volts.
If voltage is too high for 16 seconds, DTC 38 will set.

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

1. The VCM 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 Knock Sensor (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.
Also, check for proper installation of PROM (MEM-CAL).
Refer to "Intermittents". - Intermittent Malfunctions