How would I test Knock sensor wire is good (1 Viewer)

[FamilyCamper]

I recently changed the bank 2 knock sensor. Found that the wiring for both sensors was redone poorly at one point. Tested both knock sensors and they tested good but I still replaced bank 2 with the new one I had ordered. I put new connectors on and spliced the wires together with a small heat shrink connector. Both sensors should be good but now I'm getting a CEL for circuit A which is the number 1 sensor. I would like to test the wiring to make sure that that is not the cause but how can I do that? Will I be able to turn the key to on with the fuel lines off and intake off and test voltage to the sensor wire? Thanks for any help.

 

[Malleus]

What you're asking is "can I test both sides of a splice to see if current is (or can be) running through the splice"? The answer is yes, but...
you have to expose the conductor on both sides of the splice to do that. One side is easy, you just touch the DMM probe to the terminal inside the connector housing. The other end is the problem. The only point the other end of the wire is supposed to be exposed is the ECU connector. You could scrape the insulation off of the knock sensor pigtail upstream of the splice and test there, but I wouldn't.

Your best bet is to get the EWD/FSM for your year (I could post it, but I don't know what year you have) (they're both in the Resources section - LMK if they aren't and I'll put copies there for you), open the troubleshooting section of the engine control chapter and find the ECU terminal for the knock sensor. You can test there to verify the signal is getting from the sensor to the ECU. If it's not, you have a continuity problem.

A couple of related points:
1. You only need to test for continuity, not power, so you don't need to turn the ignition on.
2. You said you replaced the the connector; what did you replace them with? If you used OEM connectors, terminals and seals, you shouldn't have a problem.

 

[jerryb]

non vvti

 

[Ayune]

Page from 2004 Service Manual

 

[FamilyCamper]

What you're asking is "can I test both sides of a splice to see if current is (or can be) running through the splice"? The answer is yes, but...
you have to expose the conductor on both sides of the splice to do that. One side is easy, you just touch the DMM probe to the terminal inside the connector housing. The other end is the problem. The only point the other end of the wire is supposed to be exposed is the ECU connector. You could scrape the insulation off of the knock sensor pigtail upstream of the splice and test there, but I wouldn't.

Your best bet is to get the EWD/FSM for your year (I could post it, but I don't know what year you have) (they're both in the Resources section - LMK if they aren't and I'll put copies there for you), open the troubleshooting section of the engine control chapter and find the ECU terminal for the knock sensor. You can test there to verify the signal is getting from the sensor to the ECU. If it's not, you have a continuity problem.

A couple of related points:
1. You only need to test for continuity, not power, so you don't need to turn the ignition on.
2. You said you replaced the the connector; what did you replace them with? If you used OEM connectors, terminals and seals, you shouldn't have a problem.

Thank you this is helpful. So does the sensor just send voltage when there is a knock thus only a check for continuity is needed? It does not get any power from the engine control module?
I replaced the connector with OEM connectors that had a pigtail so I spliced those into the original wires using simple heat shrink connectors from harbor freight. Any suggestions on a better way ?

Thanks!

 

[FamilyCamper]

Page from 2004 Service Manual

View attachment 3348647

Thank you, this is helpful but my question is about the wire itself not the knock sensor. Both sensors tested well.

 

[Malleus]

Thank you this is helpful. So does the sensor just send voltage when there is a knock thus only a check for continuity is needed? It does not get any power from the engine control module?
I replaced the connector with OEM connectors that had a pigtail so I spliced those into the original wires using simple heat shrink connectors from harbor freight. Any suggestions on a better way ?

Thanks!

Correct, the sensor closes the circuit when a knock is "heard" (it's essentially the same as a light switch; close the switch and the light goes on). Otherwise, it's open and the ECU doesn't see anything. The power does come from the ECU terminal, but you still have to have continuity for that to happen. That's the first check to make. After you've determined that the wire is capable of conducting the current, you need to verify that the current is actually going from the ECU to the sensor. That's where you need the ECU troubleshooting section.

Your repair is acceptable. I'd peel the heat shrink off and check it there. You can replace it after you find what you need. To check, assume the sensor is good (otherwise you have to shake it and you need an oscilloscope to check it anyway), connect your first probe to the wire on the harness side of the repair joint. Connect the other probe to the terminal in the housing; you'll have to unplug the sensor to do this. You should get an indication of continuity. If you don't your splice is bad.

HTH

 

[FamilyCamper]

Still having issues :/ checked wiring and sensors so thinking there is an issue in the loom somewhere. CEL was coming on every drive multiple times, cleaned all connectors and it went off for 3 weeks. Came back yesterday, cleared it, and didn't come on today.
There is continuity between sensor and plug behind the intake where it goes into the loom before hitting the ECU. I can't get a reading from the intake plug to the ECU for either wire. Issue is #2 so I was expecting at least a reading on #1. Tested with a friend and made sure contact was being made in the ECU connector and the plug by the intake but couldn't get continuity on either wire?? Switched knock sensors but CEL came back on after a few weeks of driving on the same #2 side. Any ideas for how to get a better reading or other issues that may be going on?

My new idea is to loom two small wires and go directly from knock sensors / wires coming out of ECM. This would marr the harness but I would keep the wires able to tap into on the knock sensor side and I would leave a long enough tail Ecu side in case someone wanted to reextend and connect to OEM style.

 

[syrinxstar]

I just did this job. I was getting a knock sensor fault code. I replaced both since I was in there and the FSM procedures to test the sensors were inconclusive. And I replaced the starter while I was in there. And the fuel injectors. ha

In any case, I set my multimeter up for continuity and checked from the connecter at the knock sensor to the connector that plugs into the ECU in the glove box. You need the wiring diagram to see which block and which pins to check at the ECU but I could get continuity. Then I shook/jostled the wiring in the engine bay and listened to see if continuity stopped. It didn't so I felt good that it was a failed knock sensor versus a wiring issue. Buttoned it all back up and running fine for three months now.

 

[FamilyCamper]

I just did this job. I was getting a knock sensor fault code. I replaced both since I was in there and the FSM procedures to test the sensors were inconclusive. And I replaced the starter while I was in there. And the fuel injectors. ha

In any case, I set my multimeter up for continuity and checked from the connecter at the knock sensor to the connector that plugs into the ECU in the glove box. You need the wiring diagram to see which block and which pins to check at the ECU but I could get continuity. Then I shook/jostled the wiring in the engine bay and listened to see if continuity stopped. It didn't so I felt good that it was a failed knock sensor versus a wiring issue. Buttoned it all back up and running fine for three months now.

Thank you for this information. Ive had this apart 4 times now changed both sensors, wired both, cleaned all injectors and new seals all around, new starter and new gaskets. Its a lot! Very good to know that you were able to get a continuity reading, I am not sure why we could not. We had the diagram and I had a friend w me we were both confident we were on the correct pins. Can you share your detailed method for getting good contact on both ends please, especially on the ECU plug side of things. Thank you!

 

[Kofoed]

deleted

 

[JackCreasedawg]

deleted

 

[JackCreasedawg]

Thank you for this information. Ive had this apart 4 times now changed both sensors, wired both, cleaned all injectors and new seals all around, new starter and new gaskets. Its a lot! Very good to know that you were able to get a continuity reading, I am not sure why we could not. We had the diagram and I had a friend w me we were both confident we were on the correct pins. Can you share your detailed method for getting good contact on both ends please, especially on the ECU plug side of things. Thank you!

I need of some knock sensor advice. I'm getting CEL code 52 for the second time on different LCs, never managed to fix it on my old LC.
I've replaced the sensor recently and still no good. Today I got a multi meter and whipped the plug off (also new), checked the continuity of the plug terminal and pig tail, all good! Then tried to get the rear sensor off but need a better socket set.
So instead put a new crimp on the front sensor and screwed it back in, but I've ver tightened it and twisted the sensor off in the block. Spewing!
What now?
Temp fix I could splice the front into the rear sensor?

 

[FamilyCamper]

I need of some knock sensor advice. I'm getting CEL code 52 for the second time on different LCs, never managed to fix it on my old LC.
I've replaced the sensor recently and still no good. Today I got a multi meter and whipped the plug off (also new), checked the continuity of the plug terminal and pig tail, all good! Then tried to get the rear sensor off but need a better socket set.
So instead put a new crimp on the front sensor and screwed it back in, but I've ver tightened it and twisted the sensor off in the block. Spewing!
What now?
Temp fix I could splice the front into the rear sensor?

Oh my ! Post pics of the situation so we can see. I'm not sure if splicing will work it makes sense in theory but no experience on that one. How did you snap it off?? It's quite the unit of a sensor!

 

[JackCreasedawg]

Oh my ! Post pics of the situation so we can see. I'm not sure if splicing will work it makes sense in theory but no experience on that one. How did you snap it off?? It's quite the unit of a sensor!

Will get a picture for you! You're right then sensors are big, this was an aftermarket one so maybe it's just cheap and soft. Very frustrating because it's difficult to get to so I can't put much force into it

 

[Malleus]

No, you can't splice two sensors into one circuit and solve your problem. The ECU expects to see two separate signals.

 

[JackCreasedawg]

Here is the mess I've created, never used an easy out but maybe I could manage

 

[FamilyCamper]

Here is the mess I've created, never used an easy out but maybe I could manage

View attachment 3922680

Yeah I would try and just get it out using that or a welded nut to the top of it. Regarding the code did you check continuity from the sensor the the plug on the back of the block as well as from that plug to the ecu? Otherwise it could be a pin issue on the ecu from what I understand. I am still having trouble with my bank 2 but it's happening less after I cleaned all the connectors.