Knock Sensor/ Knock Sensor Wiring Harness writeup

Hello fellow enthusiasts!

Recently my knock sensor wiring harness got chewed up, and that in turn messed up the sensors as well. I'm going to write a very informal writeup on this, however I'm piggybacking off of this writeup, https://www.tacomaworld.com/threads...p0333-diy-knock-sensor-harness-repair.547066/

The link above was massively helpful and has pictures, however they only did the wiring harness and not the sensors. They also did not remove the coolant pipe and worked around it, which in my opinion was a bigger pain in the butt than just taking the pipe off.

In here, I will be explaining how to replace both the wiring harness and sensors for the 4.0 V6, of WHICH I ABSOLUTELY RECCOMEND DOING BOTH! At first, I only replaced my wiring harness and the problem came right back, so I had to do the same job TWICE! You can take that gamble too, but do you really want to do a 6-8 hour job twice? If you do want to take the gamble though since those sensors cost an arm, a leg, and a testicle/ ovary, you can use this to replace just the wiring harness since its all the same steps besides the sensors being replaced.

Here's what you will need:
Socket wrench
Breaker bar/ cheater pipe
10mm socket and wrench (ratcheting wrench is optional and will be immensely helpful)
12 mm socket and wrench
8mm hex bit/ allen key
T-40 torx (optional)
Hammer
Small/ medium sized pry bar
Towels/ foil to stuff down the intake holes
Torque wrench
Pliers suitable to remove hose clamps
A large container for coolant. The wider the better since coolant drips off of everything on its way down and spills everywhere
Funnel for coolant
Peppermint oil, or any other rodent deterrent spray (optional)
Two hose clamps

Knock sensors (89615-06010
Wiring harness (82219-0C010)
O-rings for coolant pipe (9676135031)
Air Surge Gasket (17176-0P010)
Intake Manifold Gasket (17177-AD010)
Intake Manifold Gasket (17178-AD010)
Water Outlet Gasket, need 2 (16341-AD010)
Super Long Life Coolant, need 2 (00272-SLLC2)

Steps:

1. Disconnect negative terminal on battery to prevent any shorts
2. Take off the cover by taking off the two 10mm nuts
   
3. Pop the two clamps on the air filter and separate it from the rest of the filter housing. Loosen the 10mm clamp on the throttle body, the two 10mm screws holding in the housing, then disconnect the MAF sensor and vacuum line.
4. Remove the filter housing and set aside
5. Disconnect all wiring harnesses, vacuum hoses, and coolant hoses connected to the intake plenum
6. Use the 8mm hex key and 12mm socket to remove the bolts and nuts holding in the plenum. Don't forget the two coolant lines on the throttle body and the wiring harness
7. Note, be very careful of all the other little sensors down there. You do not need to disconnect them, but be careful working around them because they're fragile and I broke the the connector off of the camshaft position sensor the first time I did this
8. Disconnect all fuel injector wires and disconnect the two quick connects on the two fuel lines towards the back of the intake by pulling off the little covers and squeezing the two sides with your fingers then pulling. Do not kink them. Have a rag handy as a little bit of fuel will come out
9. This is where you can either use that T-40 Torx or use a 12mm socket to remove the bolts holding in the lower intake. I prefer the 12 mm socket as the T-40 Torx will have a much higher chance of stripping. Don't worry about the security Torx bits, for they won't need to be removed
10. Now you should be staring at two coolant pipes and the intake passages. Cover them with rags, towels, foil, or whatever you have to keep dirt and any other junk from getting in
11. From here you can attempt to replace the wiring harness with tiny fingers, cursing, and angled pliers
12. When that doesn't work, you will need to take off your skid plate if you have one and drain your radiator. Then disconnect all the hoses going to or from the water inlet housing. Whether you disconnect hoses at the housing or where they connect will be entirely based on which side is easier to access
13. There will be 5 10mm bolts holding in the housing, two on top, one on the right side, one on the bottom right, and one in the bottom middle. This is where your wrench will be your best friend as this is a tight squeeze
14. Once that's off, you will need to cut the bands off of the metal pipes that connect the two pipes. I could not use my cut off wheel because of the angles, but maybe you can. I ended up using tin snips and mangled those bands after 30 minutes of torture. A Sawzall can be used as well
15. Undo the 10mm bolt under the bigger cooling pipe
16. Now you can use that strength you spent hours in the gym developing and yank out that pipe, or when you're not strong enough to overpower years of heat cycles on an o-ring like myself, you grab that pry bar and hammer
17. Angle the pry bar on the lip of the band you just cut and start hammering her out. Be careful not to damage the pipe. Doing this will bend that little leg that's down on the stud of that 10mm bolt you took off earlier. You should now have the clearance to lift the pipe up and shimmy that leg off the stud
18. With the pipe off, you will have access to the knock sensors and wiring harness. Simply disconnect the harness, follow it behind the motor then disconnect it from the main harness.
19. Feed your new harness through the front, fish it out from the back, then connect it to the main harness. This is where you can skip to reassembly or proceed to replace your sensors
20. To replace the sensors, all you have to do is undo the 12 mm bolts and replace them. I used my wrench to take off one of them. Don't overtighten, just snug them up and connect it to the harness
21. Optional step is to spray your rodent deterrent everywhere
22. Now to reassemble!
23. Pick off that old crusty o-ring off that pipe
24. Clean the surfaces well and put on the new o-rings. Rub a little coolant on the o-rings to help them go in easier
25. Shove the pipe in and give it a little push. Don't exert yourself yet, as it will be easier to push the pipe in when you connect it to the water inlet housing
26. I left the leg bent and didn't even put it back on the stud. You could cut it off if you'd like
27. Replace all the appropriate gaskets on your water inlet housing
28. Align the housing with the pipe and start pushing. The pipe should go in easy if you lubed the o-rings with coolant. If not, use the prybar and hammer carefully
29. As an optional precaution, put the two hose clamps around where the bands used to be. This will make sure the pipes are connected again and is a precaution against excess vibration
30. Start putting those bolts back into the housing and snug them evenly. When snug, give it 1/4 to 1/2 turn. Do not overtighten or you will strip the threads since they're aluminum
31. Reconnect all the coolant hoses
32. Blow/ wipe off any dirt and/or coolant
33. Remove your old intake gaskets if you haven't already and clean the surface well with brake cleaner
34. Put in your new intake gasket, then carefully line up the intake and drop it in. Make sure to not damage any wiring harnesses in the way
35. Hand tighten the bolts on the intake then snug them up going from the middle-out
36. Torque them to 19 foot pounds
37. Reconnect your fuel lines to the fuel rail and reconnect the wiring harnesses to each fuel injector
38. Take the old gasket off of the intake plenum and replace with the new one
39. Carefully line up the plenum and tread in the bolts/ nuts.
40. Snug then torque from the middle-out to 21 foot pounds
41. Reconnect all vacuum lines and wiring harnesses
42. Line up intake housing with throttle body then reinstall onto throttle body
43. Tighten throttle body clamp, the 2 10mm bolts, and the air filter clamp
44. Reconnect air filter with the rest of the housing and close the two clamps
45. Disconnect upper radiator hose from radiator and pour coolant into the hose
46. Make sure to leave some space in the hose so that you can reconnect it without spilling coolant everywhere
47. Reconnect upper radiator hose
48. Open cap on radiator and fill radiator till full
49. Reconnect battery terminal and start her up with the heat on full blast
50. Bleed air out of system, squeeze hose, rev to 2k RPMs for a minute, etc.
51. Put your skid plate back on after if you have one
52. Clean up your mess and enjoy the fruits of your labor- a truck that doesn't suffer from terrible fuel economy, limp mode, no overdrive, and no more knocking

Feel free to ask any questions if you're in a bind or add anything I missed. I apologize that I didn't take any pictures. Have fun y'all because this job sucked and it sucked even more to have to do it twice!

Edit: Thanks to @shaeff what I meant to say was no more misfiring, not no more knocking

 

Great writeup.

Just a note: the “no more knocking” part you may want to revise. If the knock sensors are throwing a code and truck is in “limp mode” which is basically retarded timing/fuel rich condition, that is specifically to prevent detonation/spark knock.

Bad knock sensors and/or wiring won’t cause any sort of knocking.

 

My truck ran perfectly fine before the CEL came up with the codes for the knock sensor. I did park the truck for 3 months, which is when I'm assuming some rodent took advantage. When I was driving around for a few days, mainly to different parts stores to make sure the code was consistent and to the shop to fix it, truck had no power and at some lower RPM ranges under load would knock like a mf. According to the YouTube videos and the threads I read on here, all those are common symptoms associated with the knock sensor code(s). Mine specifically said high input, if that makes a difference. All I know is that my truck drives normally again and I don't hear anymore pre-detonation

 

Misfire due to excessively retarded timing and over fueling. Not detonation.

It would be damn near impossible for you to detonate with a knock sensor code set in the ECU.

I’m glad that your truck is running better, those are classic symptoms of failed knock sensor and/or wiring.

 

That makes a lot of sense, thank you for solving that mystery. I can finally have that whole ordeal behind me now that I have the answer to the one question that was lingering in my head

 

Glad to help, regardless of how sarcastic you might be. Others might want to understand how the system actually functions. Not my problem if you’re not one of those people. :shrug:

 

No sarcasm intended lol, genuinely grateful. I hate when I don’t fully understand why my truck is doing something wrong

 

My bad, your post read as very sarcastic to me. I take it back, we’re all here to learn. I learn something new every day, that makes every day a good one.

Take care.

 

2 great links to share & save! Thank you both!