Help with knock sensors!!!
Thread Starter
Intermediate
Joined: May 2024
Posts: 27
Likes: 15
From: Arkansas
Help with knock sensors!!!
I took the intake off to change the knock sensors, braided hose for the oil pressure sensor, and to change the gaskets. The knock sensor wires have been severed on the harness side. Was just the two connection points, and the cut wires barely sticking out. Can I run two wires to the ECU pinned at 11, and 51. Do I have to ground the wires too? Do I need a whole new harness. Should I give up, and take it to a mechanic? Help please. I would prefer to do the work myself cause I'm pretty sure a mechanic is just going to replace the entire engine harness. Much appreciated
.
Joined: Apr 2013
Posts: 5,034
Likes: 1,156
From: Oregon
St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
Replacement knock harness is cheap.
Dorman makes a harness.
https://www.amazon.com/Dorman-917-03...s%2C164&sr=8-1
Dorman makes a harness.
https://www.amazon.com/Dorman-917-03...s%2C164&sr=8-1
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,080
Likes: 7,398
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
I agree with merv. You can splice those wires just fine. Just to a good job. Also I'm not sure what you mean about grounding. Just repair the harness so it is like OEM.
Also be very careful replacing Gen 3 knock sensors. I have seen people replace perfectly good sensors because they think they are doing the right thing, only to induce never ended knock sensor codes. Auto parts store knock sensors are crap. Even the replacement Delphi or AC Delco knock sensor are crap.
Also be very careful replacing Gen 3 knock sensors. I have seen people replace perfectly good sensors because they think they are doing the right thing, only to induce never ended knock sensor codes. Auto parts store knock sensors are crap. Even the replacement Delphi or AC Delco knock sensor are crap.
Pro
Joined: Jul 2021
Posts: 686
Likes: 47
From: Flatlands of Nebraska
As was mentioned....splice the wires and you'll be fine.
Depending on where the splice is, I highly suggest using either liquid electrical tape or the waterproof kind of heat shrink tubing if you have the space.
I don't use the regular kind of heat shrink tubing anymore...lesson learned from marine application.
Depending on where the splice is, I highly suggest using either liquid electrical tape or the waterproof kind of heat shrink tubing if you have the space.
I don't use the regular kind of heat shrink tubing anymore...lesson learned from marine application.
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Race Director
Joined: Oct 2004
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I would also recommend soldering wires over crimping them, and yes, use shrink tubing. Thru the years I've had several crimped connections fail, or go intermittent, and some were crimped by "professionals." In all the soldered connections I've done in my 55+ years of doing this stuff, I've never had a soldered connection fail. Ever.....
Drifting
Joined: Sep 2022
Posts: 1,787
Likes: 2,041
From: In the woods
2024 C5of the Year Finalist - Unmodified
Use marine heat shrink. Filled with goo that melts and seals the connection. I have used it on snowmobile trailer lighting for years with great results.
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,080
Likes: 7,398
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
I've used those at work for a hundred years. They are probably the best crimp style splices on earth.
At home I am cheap ***. I splice by either solder and adhesive heat shrink or if I am in a hurry or without power I use the un insulated barrel crimps and adhesive heat shrink.
Melting Slicks
Joined: Feb 2025
Posts: 2,105
Likes: 2,027
From: THE BEACH..
Yup those are it. That splice with the proper crimper and the tube over it fully sealed in you can't beat them.
For those who don't know what we are talking about, they are not cheap but they WORK.
https://www.prowireusa.com/raychem-miniseal-splices
For those who don't know what we are talking about, they are not cheap but they WORK.
https://www.prowireusa.com/raychem-miniseal-splices
Race Director
Joined: May 2006
Posts: 10,925
Likes: 475
From: EAST TENNESSEE
I would also recommend soldering wires over crimping them, and yes, use shrink tubing. Thru the years I've had several crimped connections fail, or go intermittent, and some were crimped by "professionals." In all the soldered connections I've done in my 55+ years of doing this stuff, I've never had a soldered connection fail. Ever.....
solder and heat shrink tubing,only use butt splices in temp/emergency ( automotive ) repairs.
Melting Slicks
Joined: Feb 2025
Posts: 2,105
Likes: 2,027
From: THE BEACH..
What me and @Mr. Black are talking about are stuff that's MIL Standard accepted to run with military aircraft in the air. I use them on a daily basis at work because that's what I do. They aren't your normal butt connector and way better than soldering.
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,080
Likes: 7,398
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
You should be able to find a replacement pigtail at all sorts of places including Amazon.
Example
https://www.wiringspecialties.com/ls...xPsBHOSc&gQT=2
Then splice to repair appropriately.
Example
https://www.wiringspecialties.com/ls...xPsBHOSc&gQT=2
Then splice to repair appropriately.
Thread Starter
Intermediate
Joined: May 2024
Posts: 27
Likes: 15
From: Arkansas
I agree with merv. You can splice those wires just fine. Just to a good job. Also I'm not sure what you mean about grounding. Just repair the harness so it is like OEM.
Also be very careful replacing Gen 3 knock sensors. I have seen people replace perfectly good sensors because they think they are doing the right thing, only to induce never ended knock sensor codes. Auto parts store knock sensors are crap. Even the replacement Delphi or AC Delco knock sensor are crap.
Also be very careful replacing Gen 3 knock sensors. I have seen people replace perfectly good sensors because they think they are doing the right thing, only to induce never ended knock sensor codes. Auto parts store knock sensors are crap. Even the replacement Delphi or AC Delco knock sensor are crap.
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,080
Likes: 7,398
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
I have read all the horror stories I'm aware. The first knock sensor I put in broke off at the threading bolt with maybe 10lbs of pressure. It was fun fishing that out at the bottom of the cylinder. 🙄 I got two good one...fingers crossed. Took the car to a mechanic to splice back into the harness. I'm comfortable splicing, but not on an engine harness that will cost me thousands of dollars if I eff it up.
I wish I was there, we'd have this fixed up in minutes.
Melting Slicks
Joined: Feb 2025
Posts: 2,105
Likes: 2,027
From: THE BEACH..