How To Test The Knock Sensors (1999-2006 V8 Silverado, Sierra, Suburban, Tahoe, Yukon)

Testing the knock sensors can seem quite the challenge, since they're located under the intake manifold.

But you can test them without removing the intake manifold and with just a simple multimeter.

In this tutorial, I'll show you how. You'll be able to easily find out if one or both knock sensors are bad or not.

You can find this tutorial in Spanish here: Cómo Probar Los Sensores De Detonación (1999-2006 V8 Silverado, Sierra, Suburban, Tahoe, Yukon) (at: autotecnico-online.com).

NOTE: This tutorial applies to the following vehicles:

Chevrolet:

• Silverado (1500, 2500):
  • 4.8L, 5.3L: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Silverado (2500):
  • 6.0L: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Suburban (1500):
  • 5.3L: 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Suburban (2500):
  • 6.0L: 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Tahoe:
  • 4.8L, 5.3L: 2000, 2001, 2002, 2003, 2004, 2005, 2006

GMC:

• Sierra (1500, 2500):
  • 4.8L, 5.3L: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Sierra (2500):
  • 6.0L: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Yukon:
  • 4.8L, 5.3L: 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Yukon XL (1500):
  • 5.3L: 2000, 2001, 2002, 2003, 2004, 2005, 2006
• Yukon XL (2500):
  • 6.0L: 2000, 2001, 2002, 2003, 2004, 2005, 2006

RELATED TROUBLE CODES:

• P0327 -What Does It Mean? (1999-2006 V8 Chevrolet Silverado, GMC Sierra).
• P0332 -What Does It Mean? (1999-2006 V8 Chevrolet Silverado, GMC Sierra).

Symptoms Of A Bad Knock Sensor

When the knock sensor fails, the fuel injection computer will light up the check engine light with one (or both) of the following trouble codes:

• P0327 Knock Sensor No. 1 Circuit Problem.
• P0332 Knock Sensor No. 2 Circuit Problem.

You're also going to see one or more of the following symptoms:

• Engine knock (ping) when accelerating the vehicle.
• Lack of power when accelerating under load.
• The vehicle will not pass the emissions test.

Knock Sensor Wiring Harness Connector Pin Out

Below are the circuit descriptions of the 2 wires of the knock sensors jumper wiring harness.

The knock sensors jumper wiring harness connector is located on the left side (driver side) of the intake manifold. See photo 2 of 2 in the image viewer above.

Terminal	Wire	Description
A	Dark blue (DK BLU)	Knock Sensor No. 1 Signal
B	Light blue (LT BLU)	Knock Sensor No. 2 Signal

Where To Buy The Knock Sensor And Save

If you find that one knock sensor is bad, then it's recommended that you should replace both and their wiring harness.

Since you'll need to remove the intake manifold to access the knock sensors, I want to also recommend that you avoid buying cheap brand-X knock-off knock sensors.

The following links will help you comparison shop for these items of known brand names (AC-Delco, Dorman, Standard Motor Products):

NOTE: The above knock sensor and related components fit the following vehicles: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 V8 Chevrolet Silverado, Suburban, Tahoe and GMC Sierra, Tahoe, Tahoe XL.

TEST 1: Testing Knock Sensor 1 (Front Sensor)

Testing knock sensor 1 simply involves testing its resistance with a multimeter in Ohms mode.

The wire that we're gonna' test, to check the internal resistance of knock sensor 1, is the dark blue (DK BLU) wire of the connector in the photo above.

In the photo above, I've labeled the DK BLU wire with the letter A.

RESISTANCE SPECIFICATION: The resistance specification of knock sensor 1 is 93 to 107 K Ohms.

Let's get started:

1. 1

   Place your multimeter in Ohms mode.

2. 2

   Disconnect the knock sensors jumper wiring harness.
   
   The knock sensors jumper wiring harness is located on the left side (driver side) of the intake manifold. See photo above.

3. 3

   Connect the red multimeter test lead to the male terminal that connects to the dark blue (DK BLU) wire of the connector.
   
   The DK BLU wire is identified with the letter A in the photo above.
   
   NOTE: This test is done on the knock sensors jumper wiring harness connector that has male spade terminals.

4. 4

   Ground the black multimeter test lead directly on the battery negative (-) post.

5. 5

   You should see a resistance value between 93 to 107 K Ohms on your multimeter.

Let's analyze your test results:

CASE 1: The resistance of knock sensor 1 is within the indicated range. This is the correct test result and it lets you know that knock sensor 1 is good.

You can also conclude that there are no wiring problems with the knock sensors jumper wiring harness.

If the engine is knocking (pinging), then this test result lets you know that the source of the problem is an engine mechanical problem.

CASE 2: The resistance of knock sensor 1 IS NOT within the indicated range. This test result generally lets you know that knock sensor 1 is bad and needs to be replaced.

The next step is to remove the intake manifold and:

• Visually inspect knock sensor 1 and see if it's damaged or corroded.
• Visually inspect the knock sensors jumper wiring harness for damage or corrosion.

Replace any component that is damaged/corroded.