Test I - Knock Sensor
- Code 25 Displayed. Have 4 oz. hammer ready. Begin Engine Running Self-Test. Tap on exhaust manifold above knock sensor with moderate strokes when Dynamic Response Signal appears. No WOT operation is required for this test. Check for code 25 in about 15 seconds and ignore all other codes at this time. If code 25 is generated, go to next step. If no code 25, knock system is working. Repeat Engine Running Self-Test and service other codes displayed.
- Turn key OFF and wait 10 seconds. Disconnect knock sensor. Inspect for and repair any damaged wiring. With DVOM on 20 volt scale, turn key ON, leaving engine OFF. Measure voltage at knock sensor connector between sensor signal and signal return. If voltage is between 1-4 volts, go to step 6) of this test. If less than 1 volt, go to next step. If greater than 4 volts, go to step 5) of this test.
- Turn key OFF and wait 10 seconds. Disconnect 60-pin connector at ECA. Inspect for and repair any damaged wiring. Connect breakout box and leave ECA and knock sensor disconnected. With DVOM on 200 ohm scale, measure resistance of knock sensor harness between sensor signal at connector and test pin 23 and between signal return at connector and test pin 46. If both less than 5 ohms, go to next step. If either 5 ohms or more, service open circuit and repeat QUICK TEST.
- Turn key OFF and wait 10 seconds. Leave breakout box installed with ECA and knock sensor disconnected. With DVOM on 200,000 ohm scale, measure resistance between sensor signal at connector and test pins 40, 46 and 60. If all 10,000 ohms or greater, go to step 6) of this test. If any less than 10,000 ohms, repair harness short and repeat QUICK TEST.
- Turn key OFF and wait 10 seconds. With equipment connected as in step 4), set DVOM on 20 volt scale. Turn key ON, leaving engine OFF. Measure voltage from test pin 23 to test pin 40. If .5 volt or more, repair short to power in knock sensor harness and repeat QUICK TEST. If less than .5 volt, go to next step.
- Turn key OFF and wait 10 seconds. Remove breakout box and reconnect ECA. Connect equivalent knock sensor (same part number) into harness but do not install in engine. Perform Engine Running Self-Test. When Dynamic Response Signal appears, lightly tap knock sensor with 4 oz. hammer. If code 25 appears after about 15 seconds, replace ECA, remove substitute knock sensor and repeat QUICK TEST with original sensor. If code 25 does not appear within 15 seconds, install new knock sensor and repeat QUICK TEST.