All Engines Except 2.5L & 7.4L

Check computer memory for code 43. If code 43 is present See COMPUTERIZED ENGINE CONTROLS section for proper diagnostic testing procedure, perform that test first. If code 43 is not in memory proceed with this test.
This test should be performed after other causes of spark knock have been checked, such as engine timing, EGR systems, engine temperature or excessive engine noise.
Connect "SCAN" tool to computer assembly line diagnostic link (ALDL) connector under dashboard. Set "SCAN" tool on knock signal. Run engine to 1500 RPM.
If there is a knock signal indicated in step 3), disconnect knock sensor and repeat test. If there now is no knock signal indicated, their is an internal engine knock or faulty sensor. If there is a knock signal indicated, check for routing of wire from knock sensor to ESC module for picking up false knock signals from an adjacent wire. Reroute as necessary. If routing is correct, replace ESC module.
If "SCAN" tool indicated knock signal in step 3), ESC system is working properly. If "SCAN" tool does not indicate knock signal, disconnect ESC module. Probe ground circuit at module connector (Brown wire) with a test light to 12 volts.
If test light does not glow, repair open ground circuit. If test light glows, reconnect ESC module. Disconnect knock sensor harness. Touch harness connector (Dk. Blue wire) with a test light to 12 volts. Each time test light contacts the circuit, a knock signal should be generated.
If knock signal is not indicated with "SCAN" tool, knock sensor harness (Dk. Blue wire) is open, shorted to ground or has a faulty ESC module. If knock signal is indicated with "SCAN" tool, connection to sensor or knock sensor is faulty.