04 Tahoe 5.3 Knock code

[weaponoffreedom]

04Tahoe 5.3, keep getting knock codes any thoughts?

recently done:

fuel filter
o2 sensor
tune up
evap purge solenoid
knock sensors
Fuel pressur is good

this condition was present BEFORE the above items were done. The items above have been done to fix the issue

 

[Rhymingmechanic]

Just a guess, but did you replace the wiring harness along with the knock sensors?

 

[weaponoffreedom]

Just a guess, but did you replace the wiring harness along with the knock sensors?

yes, the sensors are made up to a new harness, and the knock sensor ohm out properly.

 

[clinebarger]

Did you use GM sensors (part# 12589867)?

I've seen countless aftermarket sensors Ohm out & still set DTC's.

Unplug the knock sensor jumper harness, Key on, Both circuits on the PCM side of the harness should have close to 5 VDC measured with a DVOM. This is a Bias Voltage that the Knock Signals ride on. 5 VDC on both circuits means the wiring to the PCM is sound & the PCM is likely okay.

 

[weaponoffreedom]

Did you use GM sensors (part# 12589867)?

I've seen countless aftermarket sensors Ohm out & still set DTC's.

Unplug the knock sensor jumper harness, Key on, Both circuits on the PCM side of the harness should have close to 5 VDC measured with a DVOM. This is a Bias Voltage that the Knock Signals ride on. 5 VDC on both circuits means the wiring to the PCM is sound & the PCM is likely okay.

No I did not use the factory sensors, or at least it is unlikely. It is likely the are the Dorman Kit with harness
I did check continuity from PCM side of harness to actual PCM pins and have a connection, but will specifically check voltage, thanks.

This issue has been a thing since I bought for my daughter. Check engine light was on and the guy told me he had changed the sensors but the light stayed on. He did change them and the harness

 

[FowVay]

Call up Ivan at Pine Hollow Diagnostics and see if he'll make a house call. This stuff is his specialty.

 

[FSUwelder1212]

Put OEM knock sensors in it, aftermarket are junk. I was in a bind and put a standard motor products on a car I was working on recently and it actually made the issue worse, yet the sensor ohmed out fine. Replaced with OEM for half the price of the standard motor products off of rock auto and the issue disappeared. interestingly both sensors were made in china.

 

[weaponoffreedom]

Thanks to all, if there are no more suggestions