ok, last week i had my 95 blazer hooked up to a computer and it had one error code saying i needed a knock sensor on the driver side, so i replaced it this morning, took it back to the shop to clear the code, rode around and the CEL came back on, took it back to the shop to diagnose the code, and now its saying knock sensor mod circuit.........any ideas???

 

what are the specific error codes?

 

i dont recall the exact error code number, but the error was <insert error code here> knock sensor mod circuit

 

Is this it??

DTC P0325 Knock Sensor (KS) Circuit
Circuit Description
The VCM uses the Knock Sensors in order to detect engine detonation. This detection allows the VCM to retard the Ignition Control (IC) spark timing based on the KS signal the VCM receives. The circuitry within the knock sensor pulls down the VCM-supplied 5 volt signal, so that under a no knock condition the signal on the KS circuit measures about 1.3 volts. The knock sensors produce an AC signal that rides on the 1.3 volts DC. The signal amplitude and frequency are dependent upon the amount of the knock being experienced.

The VCM contains a replaceable Knock Sensor (KS) module. The KS module contains the circuitry that allows the VCM to utilize the KS signal and to diagnose the KS sensors and circuitry. If the KS module is missing or faulty which causes a continuous knock condition, the VCM sets this DTC.

Conditions for Setting the DTC
The DTC P0327 is not active
Engine run time is at least 120 seconds.
System voltage is greater than 10 volts but is no more than 17.1 volts.
The VCM detects a problem with the KS module circuitry that causes the knock to be indicated continuously
The above conditions met for up to 0.5 second
The KS voltage is less than 0.62 volt or more than 3.18 volts for more than 16 seconds.
Action Taken When the DTC Sets
The VCM will turn ON the MIL after 2 consecutive driving cycles with the fault active.

The VCM will use a calculated spark retard value in order to minimize the knock during the conditions when the knock is most likely to occur. The calculated value will vary based on the engine speed and load.

Conditions for Clearing the MIL/DTC
A history DTC will clear after 40 consecutive warm-up cycles have occurred without a fault
The scan tool Clear Info function or disconnecting the VCM battery feed can clear the DTC
Diagnostic Aids
Check for the following conditions:

A poor connection at the VCM. Inspect the KS module connector for the following conditions:
Backed out terminals
Broken locks
Improperly formed or damaged terminals
A damaged or improperly installed KS module. Check for the following items:
Bent pins
Deformed terminals
KS module not completely seated
Improper Knock Sensor torque specification. Torque the Knock sensor to 19 N·m (14 lb ft). Refer to

Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


.
Review the Fail Records vehicle mileage since the diagnostic test last failed in order to help determine how often the conditions that caused the DTC to set occur. This may assist in diagnosing the condition.

Test Description
The numbers below refer to the step numbers on the diagnostic table.

This step ensures that the fault is present.

This step checks for an improperly installed KS module

Step
Action
Yes
No

Schematic Reference: Engine Controls Schematics

1

Important
Before clearing the DTCs, use the scan tool to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear Info function is used.


Was the Powertrain On-Board Diagnostic (OBD) System Check performed?
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important
If you can hear the engine knock, repair the engine mechanical problem before proceeding with this diagnosti

 

Heymy 95 blazer issetting off P0326, and in my haynes manual it says it's the knock sensor "performance" (rather than fault P0325). Do you know what the difference is these two codes? Sorry if i'm kinda thread jacking here. Deadpool, did you ever find out what your code was? You could just take it to an autozone to get it read.

 

Please start a new post, this one is a year old. Thanks.