Tutorial: Knock sensor #2 repair or change (photos) (1 Viewer)

Joined
Nov 10, 2006
Messages
833
Location
Warsaw, Poland
So I've decided to post this thread after reading lots of things about the PHH and the knock sensor. The problem was that I could not find the knock sensor #2 easily in spite of so many threads about this side of the engine. So here we go... How to replace or repair a no.2 knock sensor.

The good news is that you will not need sophisticated tools to do the task. Here is the list:

--- 27mm socket
--- lots of extensions for the 27mm wrench
--- soldering iron or epoxy glue, depending on your strategy.
--- basic tools to lift your truck and take the wheel off.


1. Put your truck in P and apply the handbrake for added security. It is also good to chock one or two wheels just to be on the safe side. You definitely don't want to hold a 6000lb truck with your neck, do you?

2. Before lifting the truck, loosen the wheel nuts
3. Put a jack under the USDS and lift the truck
4. Remove the wheel and for security place the truck on jack stands. You will have a view similar to the one below. Direct yourself towards the upper right part of the area.
knk08.jpg


5. If you have mudflaps over there, you will notice that they are secured by some sort of plastic tabs/screws. Pry them off with a flat screwdriver or by hand if you know how to do it without tearing the rubber. The tabs are located where the green arrows are (there is one more above not seen in the photo). The red arrow represents where you should look to find the knock sensor.
knk07.jpg


And now let's zoom a little bit further...
knk06.jpg

The sensor is in the absolute center of the frame, on the engine block. Mine had no cable attached to it because the socket was broken.

knk05.jpg

A closeup of the sensor. I couldn't get a better shot. Being a photographer I only have big and bulky SLRs which are way harder to put in small spaces as compared to point ans shoots.

And now the glorious part.... Removal.

6. You will need a lot of extensions to do the task with ease. In my case removing the sensor took me 3 minutes. Look at the photo below.

knk04.jpg


* element 1: 27mm socket and a short extension. Put it on the sensor from the wheel side of the truck.

* element 2: long extension. No more bending under the truck, as element 1 will be visible from the engine bay. Put element 2. You can direct it under your brake booster and under your steering column. Easy.

* element 3: another extension. You definitely want to have the end of the wrench in a place where you can apply leverage. The extension #3 will let you put a wrench to the right of the brake booster for easy operation.

* element 4: a ratchet wrench or any other. The extensions give you easy access with the wrench. Put it on.

* element 5: any deep socket and extension work as a lever. I always prefer to use a larger lever than to apply force. I have more control over my actions and when a screw lets go I do not end up falling or bumping my hands against sharp objects in the engine bay. If you also want to work safely, use leverage.

Once the sensor is loose, just turn the extensions by hand and remove them in reverse order. Make sure the sensor does not pop off somewhere and gets lost.

7. At this point you can replace the sensor if you have too much $$$ or you can try to repair the old one. In my case I went with the repair. My sensor had the plastic socket broken and also the metal tab broken. All I could do was to solder a wire as an extension and solder the broken tab to the other end of the wire.

Here ew go...
knk03.jpg




knk02.jpg



knk01.jpg



I inserted the tab to the socket and have no problems with the sensor. I had to bend the tab a little bit so that it sits in the socket well. There is no retention mechanism so there's a risk of disconnecting but the probability is low. If you have more time, you can apply epoxy glue to the sensor top and to the tab/socket part. The glue will make sure that the cables stay connected.

Please note that if you have big hands, you will spend 30 minutes trying to connect the cable to the socket. You will be cursing like hell from under your truck so make sure there are no kids around. I have really small, feminine hands and was cursing like hell already.


Of course you can solder a plug if you have one. This would be the best solution. But anyway, here are some pics and tips that will make the sensor operation a lot easier.
 
Joined
Nov 10, 2006
Messages
833
Location
Warsaw, Poland
The main characteristic was a P0330 code. The details stated that the code appeared at 1950rpm, with 56% engine load. This rpm threshold is more or less when the knock sensor circuit is activated. The code appeared so it means there was no signal from the sensor. Either bad completely (little probability) or smacked cable. So there was nothing more to do than have a look at it.

There is also the possibility that timing is retarded when there is no signal from the sensor. This decreases power and increases fuel appetite. In my case I didn't feel any big power loss, probably because the other knock sensor was operational.
 
Joined
Oct 27, 2003
Messages
9,643
Location
North Cadillac
OK, great information. thanks again.

I was just wondering since i have a knock at low RPMs (like a majority of 80 owners) and i was just wondering if it was because of an issue with the knock sensor.
 
Joined
Oct 27, 2003
Messages
9,643
Location
North Cadillac
I had totally forgotten about this thread and now i'm glad it popped back up! I broke my #2 knock sensor trying to remove it during the motor overhaul so now i need to either replace it or fix it.
 

sdnative

SILVER Star
Joined
Oct 28, 2007
Messages
4,565
Location
San Diego
Bumping an old thread. Great info here. Is this part of FAQ? Should be.

I broke my sensor when doing the PHH. I was able to push it back on and it's holding, but want to fix it. If I were to go the epoxy route, what type of epoxy would be recommended?
 
Joined
Sep 17, 2003
Messages
3,990
Location
Sunnyvale, CA
I used JB weld epoxy a few years ago and it's been perfect ever since. In my case, the plastic was broken off, but the pin/spade was intact, so just a matter of pulling the plastic out of the harness end socket and using JB weld epoxy to 'stick' it back in place on the sensor.

cheers,
george.
 
Joined
Aug 7, 2015
Messages
80
Location
ohio
reviving thread...where does the cable connect to coming from sensor? And where is the other sensor? I am trying to find mine, but even if cable is knocked off, I wont know where to put it back to
 

Wayne

Bought by His blood, kept by His power
Joined
Oct 12, 2003
Messages
993
Location
Middleburg, Florida
Both knock sensors are located on the left side of the engine block, in the area between the head and upper oil pan.
 

jay

Joined
Jul 5, 2014
Messages
226
Next oil filter an identical to that is one in rear near the ground ring hanging in pic. Don't buy the aftermarket ones a heap of headaches
 

Tremek

SILVER Star
Joined
Apr 19, 2012
Messages
452
Location
Parker, CO
So I got the front driver's wheel off and started digging, and this is what I came across:

lTiv5Qjh.jpg


I'm pretty sure that smoothed off grey looking bolt is supposed to be the knock sensor, and the plug in the foreground is the harness plug? Anyone know what happened here - did someone put JB weld in the sensor, or did it melt?

Here's what the plug looks like:

kzmqcCIh.jpg


Also looks bodge-y and melty.

Should I be able to put a socket on the end of that sensor and back it out and replace it with a new one? Is that literally just a bolt in where the sensor should be? I'm so confused. Thanks, PO.
 

Users who are viewing this thread

Top Bottom