help diagnose

[RidinLow94]

Where are the ground connections that I have to worry about? Ever since I did the 6.0 swap I've had p2681 and now I've been getting a code for low voltage on my knock sensors.

The truck runs normal when the codes are off/cleared but when they come on I go rich. Its driving me nuts!! I cleaned the block connection for the ground wire coming from the battery, and the 2 on the backside which one is in the trans harness and the other is in the loom for the passenger side injectors.

any suggestions on what could cause this problem?

another symptom that leads me to a ground issue, my voltage drains down drastically on certain things. just putting up the windows or running the defroster. It'll spike and then come back up.

I don't recall nor have I seen any pinched wires

Could bad knock sensor's cause this?

How do I remove a knock sensor that wont come out? I tried replacing the back one, but when I broke it loose it just spins but doesn't unscrew. I don't know what they are called but I think there is something like this pressed in the block which the knock sensors screw into and its just spinning but doesn't come out



that's the knock sensor location on my 4.8

[1_fastsilverado]

On the knock sensor code issue, they produce their own ac voltage by a crystal inside them that vibrates, (if you already knew that I apologize) so I would look at the wire off each one being it's a signal wire to the pcm. I've also read about the torquing of them being critical when installing, and that it can affect their output. The large voltage drop isssue you are having could definately be ground related, but just to be safe double check all of your connections and look for corrosion of any kind...basically anything to cause a resistance in those circuits. Hope I could be of some help.

[country_3030]

I have replace a lot of these at the dealership. If it just spins then you have to take the valley cove off and turn the outside of the sensor with a pair of channel locks. If it is a 6.0 block then the knock sensor holes are part of the block casting (no inserts). Get the small round gasket for valley cover since you will probably rip it during removal. Over time I have learned it is best to only use gm sensors and usually replace the knock sensor sub harness at the same time.


Picture of knock sensor mounts in the valley. Note: this is a 5.3 block

[RidinLow94]

On the knock sensor code issue, they produce their own ac voltage by a crystal inside them that vibrates, (if you already knew that I apologize) so I would look at the wire off each one being it's a signal wire to the pcm. I've also read about the torquing of them being critical when installing, and that it can affect their output. The large voltage drop isssue you are having could definately be ground related, but just to be safe double check all of your connections and look for corrosion of any kind...basically anything to cause a resistance in those circuits. Hope I could be of some help.

thanks, I'll check again

I have replace a lot of these at the dealership. If it just spins then you have to take the valley cove off and turn the outside of the sensor with a pair of channel locks. If it is a 6.0 block then the knock sensor holes are part of the block casting (no inserts). Get the small round gasket for valley cover since you will probably rip it during removal. Over time I have learned it is best to only use gm sensors and usually replace the knock sensor sub harness at the same time.


Picture of knock sensor mounts in the valley. Note: this is a 5.3 block

thanks, this is what I was hoping to hear. My problem is that the sensor is stuck in and the valley cover is still on. I'm gonna try to lift the valley cover up enough to get a pair of vise grips or channel locks on it. Hopefully I can get it loose