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How to test knock sensor and wires?

tkm509

Full Member
Joined
Jun 24, 2010
Messages
16
Location
MidWest
I replaced both sensors about 4 months ago. have had several knock sensor codes this past week, all showing bank 2 low input. I also replaced the connector, from Napa, for the rear sensor when I replaced both sensors. I am wondering if I have a bad sensor or connection, or if there is a problem in the wiring. Is there a way to test the sensor and the harness? I still plan on replacing the sensors again, and the harness(GM this time)
 
You are supposed to change the harness as well... The factory harness is a weak point in the system as well as water getting into the knock sensors. Also if you wash your engine, its a good time to stop doing it.
 
I only replaced the connector that was bad. I will replace the whole harness tomorrow. I just want to know if there is a way to test the components before I replace them again( which I will do), and after I install the new parts.
 
I dont think there is any way to test, but there is a TSB posted somewhere on how you are supposed to build like a wall of silicone around the knock sensors to keep water and debris out of them.
 
TXSZ66AVLANCHE said:
I dont think there is any way to test, but there is a TSB posted somewhere on how you are supposed to build like a wall of silicone around the knock sensors to keep water and debris out of them.

thanks. read and done TSB first time around.



Does anyone else know of test for the knock sensors?
 
DO NOT TAP ON PLASTIC PARTS


Connect the DMM between the affected KS signal circuit on the sensor side and a good ground. Set the DMM
to the 400 mV AC hertz scale. Tap on the engine block near the affected KS while observing the signal
indicated on the DMM.

Is any signal indicated on the DMM while tapping on the engine block near the KS? If so then the KS and wires are good up to that point.

 
rear KS was bad, no signal before or after knocking. with or without the harness. replaced them both and the harness on Thursday, so far no issues! I don't ash the engine but do go thru the car wash sometimes, and the KS were both dry, so the TSB did work.(replaced KS in June)
 
Hey Guys I'm now to the fourm hows everyone doing. Well I had a probelm with my bank 2 KS so i went ahead and replaces both of them a week ago and had no problems till now. Both of them are now giving me codes.It looks like i should have also replace the harness. I looked around but havnt had luck finding it at any auto parts store. Does anyone have a Part numbe or is it a something i have to get at GM?
And just in case Its for my 02 Avalanche Z71 5.3 150k miles
 
tkm509 said:
I replaced both sensors about 4 months ago. have had several knock sensor codes this past week, all showing bank 2 low input. I also replaced the connector, from Napa, for the rear sensor when I replaced both sensors. I am wondering if I have a bad sensor or connection, or if there is a problem in the wiring. Is there a way to test the sensor and the harness? I still plan on replacing the sensors again, and the harness(GM this time)
IF YOU REPLACED WITH AFTER MARKET SENSORS LIKE I DID,THEY DO NOT WORK.YOU HAVE TO GET THE SENSORS AND THE  WIREHARNESS FROM THE DEALER.I FOUND OUT THE HARD WAY AND HAD TO REPAIR IT 3 TIMES.THE SMOG GUY TOLD ME NOT TO BUY AFTER MARKET KNOCK SENSORS AND TO BUY A NEW  WIREHARNESS.SO TO SAVE MONEY I PURCHASED AFTER MARKET SENSORS AND CHECK ENGINE LIGHT STILL ON=  FAILED. SECOND TIME I INSTALLED SENSORS FROM DEALER BUT DIDNT CHANGE WIREHARNESS, CHECK ENGINE LIGHT WAS STILL ON =FAILED.WENT TO DEALER GOT WIREHARNESS AND INSTALLED IT, CHECK ENGINE LIGHT WAS OFF AND IT PASSED.--IF YOUR GOING TO FIX YOUR KNOCK SENSOR PROBLEM TRUST ME DO IT RIGHT THE FIRST TIME AND BUY OEM DEALER PARTS ITS A MUST FOR THE KNOCK SENSOR FIX.(I TRY TO SAVE A BUCK AND IT BIT ME IN THE ASS HARD)  GOOD LUCK!!!!!
 
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