Test H - Knock Sensor
NOTE:
Use DYNAMIC RESPONSE CHECK as specified in steps 1) and 6). There is no need to perform WOT during this test. For additional information see QUICK TEST DIAGNOSTIC AID, DYNAMIC RESPONSE CHECK.
To prevent replacement of good components, be award that the following non-EEC related areas may be at fault: fuel quality, engine condition (valves, vacuum leaks, valve timing, EGR valve, etc.) and spark timing.
- Code 25 Displayed. Have 4 oz. hammer ready. Perform ENGINE RUNNING SELF-TEST. When DYNAMIC RESPONSE CHECK signal appears, lightly tap above Knock Sensor (KS) with 4 oz. hammer. After 15 seconds, check for code 25. Ignore all other codes at this time. If code 25 is displayed, go to next step. If code 25 is not displayed, knock system is okay. Repeat ENGINE RUNNING SELF-TEST and service other codes.
- Turn key off and wait 10 seconds. Disconnect knock sensor. Inspect for and repair any damaged wiring. Set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage at knock sensor connector between KS signal and signal return. If reading is higher than 4 volts, go to step 5). If voltage is between 1 and 4 volts, go to step 6). If reading is less than 1 volt, go to next step.
- Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA and knock sensor disconnected. With DVOM on 200-ohm scale, measure resistance between knock sensor connector signal return and test pin No.46, and between knock sensor connector KS signal and test pin No. 23. If either reading is 5 ohms or more, service open circuit and repeat QUICK TEST . If both readings are less than 5 ohms, go to next step.
- Turn key off and wait 10 seconds. With breakout box installed, ECA and knock sensor disconnected, set DVOM on 200,000-ohm scale. Measure resistance between knock sensor connector KS signal and test pins No. 40, 46 and 60. If all readings are 10,000 ohms or higher go to step 6). If any reading is less than 10,000 ohms, repair shorts in harness and repeat QUICK TEST .
- Turn key off and wait 10 seconds. With breakout box installed, ECA and knock sensor disconnected, set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage between test pins No. 23 and 40. If reading is 0.5 volt or more, repair knock sensor harness short to power, and then repeat QUICK TEST . If reading is less than 0.5 volt, go to next step.
- Turn key off and wait 10 seconds. Remove breakout box and connect ECA. Connect substitute knock sensor (same Part No.) into harness but do not install in engine. Perform ENGINE RUNNING SELF-TEST. When DYNAMIC RESPONSE CHECK signal appears, lightly tap knock sensor with 4 oz. hammer. If code 25 appears 15 seconds later, replace ECA. Remove substitute knock sensor and repeat QUICK TEST with original sensor. If code 25 does not appear 15 seconds later, install new knock sensor and repeat QUICK TEST .