Test U - Knock Sensor
- Code 25. Prepare vehicle for Engine Running Self-Test and have 4 oz. hammer ready. Tap on exhaust manifold above knock sensor when Dynamic Response Signal appears. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST . Again tap on exhaust manifold when Dynamic Response Signal appears. Check for code 25 in about 15 seconds. If code 25, go to next step. If no code 25, knock system okay. Repeat KEY ON-ENGINE RUNNING (KOER) SELF-TEST and service other codes.
- Turn ignition off and wait 10 seconds. Disconnect knock sensor and inspect. With DVOM on 20 volt scale, turn ignition on and measure voltage at knock sensor harness between sensor signal circuit and signal return circuit. If voltage is 1-4 volts, go to step 6 . If less than 1 volt, go to next step. If greater than 4 volts, go to step 5 .
- Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect for damaged pins, corrosion and loose wires. Connect breakout box and leave ECA and knock sensor disconnected. With DVOM on 200 ohm scale, measure continuity of knock sensor harness between sensor signal circuit and box pin 23 and between signal return circuit and box pin 46. If both less than 5 ohms, go to next step. If either 5 ohms or more, repair open circuit and repeat QUICK TEST .
- Turn ignition off and wait 10 seconds. Breakout box installed and ECA and knock sensor disconnected. With DVOM on 200,000 ohm scale, measure resistance from sensor signal circuit of knock sensor harness to box pins 40, 46 and 60, in turn. If all 10,000 ohms or greater, go to step 6 . If any less than 10,000 ohms, repair harness short and repeat QUICK TEST .
- Turn ignition off and wait 10 seconds. With equipment connected as in step 4 , set DVOM on 20 volt scale. Measure voltage from box pin 23 to pin 40. If .5 volt or more, repair knock sensor harness short to power and repeat QUICK TEST . If less than .5 volt, go to next step.
- Turn ignition 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 KEY ON-ENGINE RUNNING (KOER) 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 sensor and repeat QUICK TEST .